1. Introduction & Background

Welcome readers.

This is the twelfth published report from the National Clinical Audit on Severe Maternal Morbidity (SMM) in Ireland since the inception of the audit in 2011. It is the first web-based report and provides information on the incidence of clearly defined SMM events occurring for the reporting years 2023 and 2024. Information on maternal characteristics, management of delivery and neonatal outcome in women experiencing SMM are also detailed in this report.

Background

Severe Maternal Morbidity (SMM) has been widely acknowledged as an important quality indicator of obstetric and maternity care, particularly in high-income countries where maternal fatality rates are relatively low.^1,2 As outlined in our study on maternal morbidity and mortality, maternal death, although tragic, is the last point in the spectrum of adverse pregnancy events, representing the tip of the iceberg of adverse maternal outcomes.³ For each maternal fatality occurring, many more women survive and may carry with them long-term consequences. Low rates of maternal fatalities may indicate that morbidities are managed effectively but their incidence requires surveillance, and their prevention requires greater attention.¹

In this context, the National Perinatal Epidemiology Centre (NPEC) in collaboration with the NPEC SMM Advisory Group, has collected and analysed data on SMM from Irish maternity units since 2011. The fundamental aim of the audit is to provide a national surveillance of the incidence of women experiencing severe maternal morbidities, to identify quality improvement initiatives and make recommendations for the improvement of maternal care for women in Ireland. Ongoing audit on maternal outcomes is vital to monitor quality and responsiveness of maternity care and services.

Figure I. Map of maternity units and hospital groups in the Republic of Ireland, 2024.

Information on the 2023 and 2024  methodology, definitions, and inclusion criteria can be found here

4. National Rate

In 2023 and 2024, there were 357 and 482 women who experienced one or more SMM respectively in Ireland. Table 1 details the national number of women experiencing an SMM event, total maternities and SMM rates derived from all 19 Irish maternity units since the first year of the audit, 2011.   

Table 1: Incidence of severe maternal morbidity (SMM) in Ireland, 2011-2024.     

_{Note: Rate ratios compare the rate for each year against the rate for the baseline year 2011. P-values assess the statistical significance of the difference between the rate for each year and the rate in 2011. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.} 

Based on this national clinical audit, the SMM rate was 6.64 per 1,000 maternities in 2023, and 9.19 per 1,000 maternities in 2024. The 2023 and 2024 rates were 72% and 139% higher respectively than the rate of 3.85 per 1,000 maternities in 2011. Thus, the incidence has changed from one SMM event for every 260 maternities in 2011 to one event in 151 and 109 maternities in 2023 and 2024 respectively. The SMM rate has been relatively stable at approximately six events per 1,000 maternities since 2015, with an increase recorded in 2024. The initial increase was largely confined to the first years of the audit, which could reflect enhancement of case ascertainment as the SMM audit matured.

5. Specific Morbidities

The SMM rate is a composite rate of a group of clearly defined severe maternal morbidities. Nearly three quarters of the women who experienced SMM in 2023 and 2024 were diagnosed with one morbidity (n=620, 74%); 21% (n=174) were diagnosed with two morbidities; 4% (n=37) with three morbidities and approximately 1% (n=8) experienced four or more morbidities.

Table 2 details the frequency of the specific SMM events. As in recent years, major obstetric haemorrhage (MOH) was the most frequently reported morbidity in 2023 and 2024, accounting for over half of all SMM cases (n=428, 51%). The second most common and reportable SMM was ICU/CCU admission, which was experienced by 403 women (48%). Peripartum hysterectomy was the next SMM most frequently reported with 6% of women (n=52) experiencing this. Further SMMs which were also frequently reported included pulmonary embolism (5%), septicaemic shock (4%), and renal or liver dysfunction (4%). Acute respiratory dysfunction was diagnosed in 24 women (3%), uterine rupture in 22 women (3%), and pulmonary oedema in 20 women (2%). The remaining seven specific organ dysfunction SMMs were relatively rare and can be found in Table 2.

Table 2: Frequency of specific severe maternal morbidities (SMMs) in Ireland, 2023 and 2024.     

_{Note: n represents the number of women affected by the specific morbidity; more than one morbidity may apply per woman % is based on the total number of women affected; ICU=intensive care unit; CCU=coronary care unit.}

6. Major Obstetric Haemorrhage (MOH)

Of the 428 MOH events reported in 2023 and 2024, detailed case information was submitted by 18 maternity units (n=351). Of these 71.5% (n=251) involved an estimated blood loss ≥2,500ml without a transfusion of ≥5 units of blood, 4% (n=14) involved a transfusion of ≥5 units of blood without an estimated blood loss of ≥2,500ml and 24.5% of MOH cases (n=86) met both criteria.

Twenty-one (6%) of these 351 cases of MOH cases reported in 2023 and 2024 were associated with early pregnancy loss (including miscarriage, ectopic, and termination of pregnancy) and occurred between four and 23 weeks' gestation.

The mode of delivery was known for 330 women who experienced MOH and did not experience an early pregnancy loss. Over half (n=194, 58.8%) gave birth by caesarean section and 136 (41.2%) had a vaginal delivery. The vast majority of these MOH cases occurred on day of delivery (n=316, 95.8% of 330), primarily post-delivery. A further 13 cases of MOH occurred in the postnatal period (day 1 to day 22 post-delivery). One further case occurred in the antenatal period.

Table 3: Primary cause of Major Obstetric Haemorrhage (MOH) by mode of delivery, 2023 and 2024.        

_{Note: Data from 18 of 19 maternity units. In 2023 the primary cause of MOH was unknown for 7 women. In 2024 the primary cause of MOH was unknown for 23 women. Tables for individual reporting years are available in appendix.}

The primary cause of MOH was not reported for 30 women (14 vaginal deliveries and 16 CSs). As shown in Table 3 and Figure 1, the main reported cause of MOH for women with a vaginal delivery in 2023 and 2024 was retained placenta/membranes (n=47 of 122, 38.5%) followed by uterine atony (n=43 of 122, 35.2%).

For women experiencing a MOH who had a caesarean section, the most common primary cause of MOH reported was uterine atony (n=50 of 178, 28.1%) followed by placenta praevia (n=32 of 178, 18%).

Among the 26 women who delivered by caesarean section where the cause of MOH was reported as ‘other’, a wide variety of conditions were associated with the MOH including: fibroids, arteriovenous malformation (AVM), haemoperitoneum, lower segment uterine tears and bleeding from the placental bed.

Increasing rates of MOH warrant ongoing surveillance and audit. A detailed national audit of MOH events was conducted for the reporting years 2021 and 2022 by the NPEC and is available on the NPEC website (here).

Further, the Postpartum Haemorrhage Quality Improvement Initiative (PPHQII), a collaboration between the NWIHP and the NPEC, has been implemented nationally and is addressing standardised approaches through unit led toolkits in the evaluation of blood loss and in the management and review of PPH/MOH events.¹⁰ 

Figure 1: Primary Cause of Major Obstetric Haemorrhage (MOH) by mode of delivery, 2023 and 2024.

_{Note: Data from 18 of 19 maternity units. In 2023 the primary cause of MOH was unknown for 7 women. In 2024 and the primary cause of MOH was unknown for 23 women.}

Trends in major obstetric haemorrhage (MOH)

Nationally, there were 191 and 237 women experiencing MOH in 2023 and 2024 respectively. This includes all MOH events from the 19 Irish maternity units. The 2023 MOH rate was 3.55 per 1,000 maternities, with a MOH rate of 4.52 per 1,000 maternities in 2024, representing an increase from recent years (Table 4). A 97% rate increase has been observed from 2011 to 2024. MOH remains one of the main challenges for service providers and clinical staff as highlighted in a recent research study on increasing MOH rates in Ireland.¹¹

Table 4: Incidence of major obstetric haemorrhage (MOH) in Ireland, 2011-2024.         

_{Note: Rate ratios compare the rate for each year against the rate for the baseline year 2011. P-values assess the statistical significance of the difference between the rate for each year and the rate in 2011. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.}

7. Peripartum Hysterectomy (PH)

The infrequency of PH compared to MOH makes it difficult to access time trends based on annual rates. Table 7 details the incidence of PH by triennium. In the early years of this national audit, there was a consistent rate of peripartum hysterectomy of approximately 0.33 per 1,000 maternities. This is equivalent to one in every 3,000 women experiencing a peripartum hysterectomy. The rate has increased since, to 0.53 per 1,000 maternities in 2022-2024.  This indicates that one in every 1,900 women giving birth in Ireland experience a peripartum hysterectomy (Table 7).

This Irish rate is higher than the rate reported in earlier studies in the United Kingdom (0.41 per 1,000 births)¹⁴ but it is lower than the rate reported in the USA and Australia (0.82 per 1,000 and 0.85 per 1,000 respectively).^15,16

Table 7: Incidence of peripartum hysterectomy (PH) in Ireland, 2011-2024.     

_{Note: Rate ratios compare the rate for each triennium against the rate for the baseline triennium 2011-13. P-values assess the statistical significance of the difference between the rate for each triennium and the rate for 2011-13. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.} 

Of the 52 women who required a peripartum hysterectomy (PH) in 2023 and 2024, over a third (n=19; 36.5%) occurred in three large tertiary maternity units, of which four were reported in women following in-utero transfer. For the remaining PH events, approximately one quarter (n=15 of 52; 28.8%) were performed in units with annual births between 2,500 and 6,000; and eight PHs (15.4%) occurred across smaller maternity units with annual births <2,500.

Placenta Accreta Spectrum (PAS), formerly known as morbidly adherent placenta (MAP), is a recognised risk factor for peripartum hysterectomy.^17,18 A study conducted by the NPEC confirmed the established association between previous caesarean section (CS), MAP and PH.¹⁸ In this 2023/2024 SMM audit, PAS, was the reported indication for PH in the majority of cases (n=30, 57.7%), followed by MOH with a blood loss ≥2,500ml due to uterine atony (n=19 of 52; 36.5%). Two (3.8%) were related to other obstetric issues as follows: post-partum haemorrhage <2,500 mls (n=1), and uterine and vaginal wall rupture (n=1). An additional case was due to placenta praevia (1.9%).

Of the 52 women who required a peripartum hysterectomy in 2023 and 2024, further obstetric details were available for 42 women. The majority (n=30 of 42, 71.4%) of the women experiencing PH had a previous caesarean section. Over one third (n=16 of 42; 38.1%) of the PH cases in 2023 and 2024 were reported as planned procedures, of which half (n=8 of 16; 50%) also involved the procedure of interventional radiology (IR). PAS was the reported indication for PH in all these 16 cases. Adjunctive IR techniques aim to reduce blood loss and national guidelines recommend that IR techniques be reserved for PAS cases where ultrasound and MRI suggest high risk for maternal haemorrhage at time of birth.¹⁹

Considering the increasing caesarean section rate, this underscores the value of research on the incidence of, and risk factors associated with PAS. Research on PAS is underway and a national guideline on the diagnosis and management of ‘Placenta Accreta Spectrum’ was published in 2022.²⁰ 

8. Intensive Care Unit/Coronary Care (ICU/ CCU) Unit Admission

The details of the specific SMMs involved in the 403 admissions into an ICU/CCU in 2023 and 2024 are outlined in Table 5. Approximately 30% of these involved MOH, 7% (n=28) were associated with septicaemic shock, 7% (n=26) were related to peripartum hysterectomy, and 23 admissions (6%) were associated with acute respiratory dysfunction.

Table 5: Specific severe maternal morbidities (SMMs) in women admitted to an intensive care unit or coronary care unit (ICU/CCU) in Ireland, 2023 and 2024.     

_{Note: n represents the number of women affected by the specific reportable SMM; % is based on the total number of women admitted to ICU/CCU in 2023 and 2024. More than one SMM may apply per woman; *women admitted to ICU/CCU due to other morbidities or other issues not listed.}

Approximately half of the women admitted into an ICU/CCU in 2023 and 2024 did not experience another SMM as defined in this audit, as shown in the table by “none of the above” (n=207, 51%). The values for 2023 and 2024 represent an increase in ICU admissions for morbidities other than SMMs as defined in this audit in comparison to values from recent years (Figure 2). As acknowledged in previous reports, admission to ICU/CCU in cases not meeting the criteria of SMM as defined in this audit does not imply inappropriate use of ICU/CCU facilities but suggests the requirement of a higher level of observation or maternal care in units with limited resources.

Figure 2: Trend in the rate of ICU admissions, 2011-2024.

Of these cases, requiring a higher level of observation (Level 1, 2 or 3 Care; See Appendix), indication for ICU admission is available from 18 maternity units (n=183). These cases were associated with a wide variety of maternal complications due to both direct obstetric (n=84, 45.9%) and non-obstetric causes (n=99, 54.1%). Direct obstetric complications included post-partum haemorrhage (PPH) with a blood loss <2,500mls (n=45, 24.6%), pre-eclampsia (n= 28, 15.3%), and pregnancy-related infection (n=11, 6.0%). ICU admissions due to non-obstetric complications primarily involved monitoring of a range of medical and surgical conditions (n= 69, 37.7%) including sickle cell disease and diabetic ketoacidosis (DKA). Cardiac conditions accounted for a further 17 cases (9.3%), and non-obstetric sepsis a further 13 cases (7.1%). 

In 2023 and 2024, three quarters of the ICU/CCU admissions with no other reported morbidity as defined in this audit occurred in small maternity units with annual births <2,500 (n=137, 74.9%).

The correlation between Irish maternity units with less than 2,500 births per annum and increased likelihood of Level 2 care provided in ICU/CCU facilities was identified in the NPEC National Audit of Critically Ill Women in Obstetrics in 2014-2016.¹² Within the Irish context, ICU admission in and of itself is not a reliable proxy for having received level 2 or 3 obstetric critical care.¹³ This was also evident for the reporting years 2023 and 2024 (Table 5.1).

Table 5.1: Conditions leading to ICU/CCU admission in cases with no SMM as defined in this audit, according to size of maternity unit (classified according to annual births); 2023 and 2024.        

_{Note: Data from 18 of 19 maternity units.  Values are shown as n (%) unless otherwise stated. a Obstetric haemorrhage with <2,500mls and not receiving 5 or more units of blood; b Includes monitoring and treatment with MgSO4; c Sepsis not septic shock, d ‘Other’ surgical or medical condition.}

Trends in ICU/CCU admissions

A total of 162 women experienced intensive care unit/coronary care unit (ICU/CCU) admission in 2023, a rate of 3.02 per 1,000 maternities. In 2024, 241 women were admitted to ICU/CCU, a rate of 4.59 per 1,000 maternities. This reflects a statistically significant increase in the rate of ICU/CCU admission in recent years (Table 6).

Table 6: Incidence of intensive care unit/coronary care unit (ICU/CCU) admission in Ireland. 2011-2024.          

_{Note: Rate ratios compare the rate for each year against the rate for the baseline year 2011. P-values assess the statistical significance of the difference between the rate for each year and the rate in 2011. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.}  

Figure 2 illustrated the trend in the rate of ICU/CCU admission, as well as the rate of ICU admission with no other SMM, and the rate of ICU/CCU admission with an associated SMM as defined in this audit.

Figure 3 illustrates the trend in the rate of SMM as defined in this audit and the trend in rates for MOH and ICU/CCU admission. A steady increase in the rate of SMM is evident from 3.85 to 6.29 per 1,000 maternities during 2011-2022. Another increase is evident for 2024, with SMM rate of 9.19 per 1,000 maternities. The increase in the SMM rate during the first half of this period was primarily due to the increase in ICU/CCU admissions. During the more recent years, the increase in the SMM rate largely reflected the increase in MOH and ICU/CCU admission.

Figure 3: Trend in the rate of severe maternal morbidity (SMM), major obstetric haemorrhage and intensive care unit/coronary care unit (ICU/CCU) admission, 2011-2024.

9. Other SMM

Trends in renal or liver dysfunction

The infrequency of some specific SMMs, such as renal or liver dysfunction, compared to MOH and ICU/CCU admission makes it difficult to assess time trends based on the annual rate. However, the period of the SMM audit is long enough to allow their time trend to be examined by triennium. The 69 women experiencing renal or liver dysfunction reported in 2011-2013 gave a rate of 0.35 per 1,000 maternities. A very similar rate of 0.32 per 1,000 maternities was reported for 2022-2024 (n=49). Data from one tertiary maternity hospital were not available for 2023; the number of national maternities were adjusted accordingly.

Table 8: Incidence of renal or liver dysfunction in Ireland, 2011-2024.                         

_{Note: Rate ratios compare the rate for each triennium against the rate for the baseline triennium 2011-13. P-values assess the statistical significance of the difference between the rate for each triennium and the rate for 2011-13. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital  from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014, 2015 and 2023. CI= confidence interval.}  

Trends in pulmonary embolism

The incidence of reported cases of pulmonary embolism (PE) has increased over the years of the SMM audit. The rate of 0.24 per 1,000 maternities in 2011-2013 indicates that one woman in approximately 4,000 experienced a PE. The rate of 0.31 per 1,000 indicates that in 2022-2024 one woman in approximately 3,000 experienced a PE (Table 9).

Recent reports on maternal mortality in Ireland and the UK have identified thrombosis/ thromboembolism as a leading direct obstetric cause of maternal death.^21,22 At 0.31 per 1,000 maternities, the incidence of PE in Ireland was more than twice the reported rate in the UK (0.14 per 1,000 maternities). Notwithstanding, we believe the Irish rate reported here may represent an underestimate, as many postpartum women with PE may be unknown to maternity units because the women would present to general hospitals. Previous research has shown that thrombosis has been the main cause of direct maternal mortality in Ireland in past years with one death due to thrombosis for every 35 cases of pulmonary embolism.²³

Table 9: Incidence of pulmonary embolism (PE) in Ireland, 2011-2024.            

_{Note: Rate ratios compare the rate for each triennium against the rate for the baseline triennium 2011-13. P-values assess the statistical significance of the difference between the rate for each triennium and the rate for 2011-13. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.}  

Trends in septicaemic shock

The reported incidence of septicaemic shock was low at the start of this SMM audit, with a rate of 0.12 per 1,000 maternities. The increase in reported cases in in the early years of this audit may have reflected an increased awareness of sepsis following the introduction of guidelines on sepsis and the implementation of the Irish Maternity Early Warning System.^24,25 Since then, the rate has decreased to 0.31 per 1,000 in 2022-2024 though this is still greater than the rate reported for 2011-2013 (Table 10).

Table 10: Incidence of septicaemic shock in Ireland, 2011-2024.

_{Note: Rate ratios compare the rate for each triennium against the rate for the baseline triennium 2011-13. P-values assess the statistical significance of the difference between the rate for each triennium and the rate for 2011-13. Poisson 95% confidence intervals were calculated for the rate and rate ratios. The figure for maternities is the national number of women who gave birth, based on births in hospital from HIPE data for 2011-2022 and based on all births from the HPO in 2023-2024. Maternities in one non-participating unit were excluded for 2011, 2012, 2014 and 2015. CI= confidence interval.}  

The frequency of the specific SMMs renal or liver dysfunction, peripartum hysterectomy, PE and septicaemic shock are relatively similar and the trend in their incidence by triennium illustrated in Figure 4 shows some similarities as well. This includes the significant rise and subsequent gradual decrease in the reported incidence of renal or liver dysfunction and of septicaemic shock and the steady increase in the rate of peripartum hysterectomy.

Eclampsia, uterine rupture and intervention radiology

Trends over time cannot be assessed for the incidence of eclampsia, uterine rupture and intervention radiology given the relatively small number of cases. However, based on the most recent five-year period, 2020-2024, from a total of 273,679 maternities in the country’s 19 maternity units, 41 cases of eclampsia, 62 cases of uterine rupture and 48 cases of intervention radiology were reported. This gives a rate of eclampsia of 0.15 per 1,000 maternities, which is lower than reported for the UK (0.27 per 1,000 maternities) and Netherlands (0.54 per 1,000 maternities).²⁶ The Irish rate of uterine rupture for 2020-2024 was 0.23 per 1,000. This is quite low considering that a recent study of nine European countries reported national rates ranging from 0.16 to 0.78 per 1,000 deliveries.²⁷

Interventional radiology (IR) is a SMM based on management criteria. Adjunctive IR techniques are used to reduce blood loss in women at risk for maternal haemorrhage at time of birth and thus reduce the requirement for blood transfusion and peripartum hysterectomy (PH).²⁸ IR facilities are not available in all Irish maternity units and in some incidences are provided for in acute adult hospitals. In this 2023 and 2024 SMM audit, of the 19 reported cases of IR, seven were associated with PH, three were associated with MOH, and a further three involved both MOH and PH. In most cases (n=16 out of 19, 84.2%), it was reported that IR was a planned procedure.

10. Variation in Rates by Maternity Unit

Variation in the SMM rate in 2024 across the 19 Irish maternity units is illustrated in the funnel plot in Figure 5. A diagrammatic aid outlining the interpretation of a funnel plot in the context of the findings of this audit in 19 maternity units is detailed in the methods section of this report. Differences in rates between units must be interpreted with caution as they may not reflect care given but could reflect differences in levels of reporting and/or differences in the risk profile of the pregnant women presenting to the units. The NPEC disseminates unit specific reports to all maternity units, thus informing them of their SMM rates with reference to the national annual rate and trend data over time.

Figure 5 shows that one unit had an SMM rate below the 99.8% lower limit, with a rate of 3.67 per 1,000 maternities, compared to the national rate of 9.19 per 1,000 maternities. Two units recorded SMM rates between the lower 95% and lower 99.8% limit, at a rate of 5.91 and 5.92 per 1,000 maternities respectively. Three units recorded an SMM rate between the upper 95% and the upper 99.8% limit at 15.53, 16.92 and 17.35 per 1,000 maternities respectively. One unit had an SMM rate above the 99.8% upper limit, at 26.36 per 1,000 maternities.

The funnel plot in Figure 6 illustrates the variation in the SMM rate by maternity unit after exclusion of the 119 women who were admitted to an ICU/CCU in 2024 with no other SMM experienced as defined in this audit. Variation in SMM rate across the maternity units was reduced after this adjustment. The adjusted national SMM rate was 6.92 per 1,000 maternities.

The plot shows that one unit had an adjusted SMM rate below the lower 95% limit, which was also recorded in 2023. Due to this occurring in two consecutive years, this makes the unit a statistical outlier according to the criteria for the National Office of Clinical Audit (NOCA) escalation policy.²⁹

No other units were outside the 95% confidence limits for 2024.

Figure 7 illustrates the variation across the country’s 19 maternity units in the rate of MOH due to an estimated blood loss of at least 2,500ml and/or a transfusion of five or more units of blood. In 2024, all the maternity hospitals had a MOH rate within the 99.8% confidence limits. Two units had a rate between the lower 95% confidence limit and the lower 99.8% confidence limit, with rates of 1.84 and 2.28 per 1,000 maternities respectively. These are lower than the 2024 national MOH rate of 4.52 per 1,000 maternities.

Three units had rates between the upper 95% confidence limit and the upper 99.8% confidence limit. For all these units between the 95% and 99.8% confidence limits, none were within these limits for two consecutive years, and therefore not considered a statistical outlier, according to the NOCA escalation policy. Of note, in 2024, two cases of MOH occurred in women choosing ‘free birth’ who subsequently presented to two separate maternity units following birth at home, out with the care of the HSE home birth service.

Variances in rates of MOH between units may reflect variances in practices of estimating blood loss. We have previously recommended that a standardised quantitative approach, involving volume and weight assessment to estimate blood loss, should be considered for use in all maternity units and that development of a national toolkit would assist standardisation of such an approach.^30,31 This is currently being addressed by the national PPHQII which aims to evaluate and standardise the management of PPH.³²

11. Maternal Characteristics

Data in the following sections (maternal characteristics, level of care, neonatal outcomes) were submitted by 18 of the 19 maternity hospitals (2023 n = 291, 2024 n = 406).

Age

Maternal age was recorded for 696 of all 839 women who experienced a severe maternal morbidity (SMM) in 2023 and 2024 and ranged from 15 to 55 years (mean=33.9 years, SD=6.1 years). The age distribution of women with an SMM in 2021-2024 is detailed in Table 11. In 2024, the individuals’ age profile was broadly similar to the population of women who gave birth. However, women in the younger age groups were under-represented among those who experienced SMM (52.7% of SMM cases were aged <35 years vs. 60.1% of all maternities) while women aged at least 35 years were over-represented (46.3% vs. 39.9%).

Table 11: Age distribution of women who experienced severe maternal morbidity (SMM), 2021-2024.    

_{Note: Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. Values are shown as n (%) unless otherwise stated. Age unknown for 1 woman experiencing SMM in 2023 * Represents the sum of the data detailed in the two rows above (<20yrs and 20-24yrs). **Data for all maternities provided by the Healthcare Pricing Office (HPO).}

Previous pregnancy

Previous early pregnancy loss was reported for 230 of the 697women (33%). Of these women, 29 (4.2%) were reported as experiencing 3 or more previous pregnancy losses before 24 weeks’ gestation.

Approximately 42% (n=294) of the women who experienced an SMM in 2023 and 2024 were nulliparous which is similar to previous years and to the percentage of nulliparous women among all maternities in 2022 (Table 13). Women with one previous completed pregnancy were under-represented among SMM cases relative to the population of women who gave birth in 2021 (29.5% vs. 34.0%) whereas women with at least three previous completed pregnancies were over-represented among those who experienced SMM (11.6% vs. 7.9%).

Table 12: Parity for women who experienced severe maternal morbidity (SMM), 2021-2024.      

_{Note: Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. Values are shown as n (%) unless otherwise stated. *Parity was not known for one woman who experienced SMM in 2022 and one woman in 2024. **Data for all maternities provided by the Healthcare Pricing Office (HPO).}

Body mass index

Body mass index (BMI) for the women who experienced SMM in 2023 and 2024 ranged from 15.6 to 77.9 kg/m². BMI was not known for 52 (7.5%) of the women.

Of the 645 women with a known BMI who experienced SMM in 2023 and 2024, approximately 31% had a BMI in the healthy range, 32% were overweight and 35% had obesity (Table 13).

It was also observed that, of the total number of women experiencing two or more SMMs in 2023 and 2024, a higher proportion (72.4%) were overweight or had obesity.

As shown in Table 13, in 2024 women with a BMI less than 25 kg/m² were underrepresented among SMM cases (34.9% vs. 45.2% in the population) whereas women with a BMI in the obese category (BMI >=30kg/m2) were overrepresented relative to the population of women who gave birth in hospital in 2024 (33.9% with SMM vs 23.2%).

Table 13. Body mass index (BMI) for women who experienced SMM, 2021-2024.

_{Note: * Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. BMI was not known for 24 women who experienced SMM in 2021, 11 women in 2022, 24 women in 2023 and 28 women in 2024. Data on maternities by BMI were obtained for 32,257 women who gave birth or booked to give birth in one of eight of the country’s maternity hospitals/unit. This is 61.5% of the 52,458 women who gave birth in hospital in 2024, according to HPO data. We multiplied the BMI data on 32,257 women by 1.63 (i.e. 100%/61.5%) to estimate the national number of maternities by BMI category. ** Represents the sum of the data detailed in the 2 rows above (underweight and healthy).}

BMI associated with specific SMMs

High BMI has been associated with maternal mortality and morbidity, in particular, morbidities such as pulmonary embolism, kidney disease and complications of anaesthetics.^33-36 The four most recent years of this clinical audit, 2021-2024, provide a sufficient number of cases to compare the risk of eight specific SMMs among women with high BMI compared to women with low BMI. Women with a high BMI were at higher risk of all but one of the most common eight SMMs and the difference was statistically significant for four (Table 14). Women with high BMI had 55% higher risk of MOH, 83% higher risk of ICU/CCU admission and 87% higher risk of peripartum hysterectomy.

Table 14. Risk of specific severe maternal morbidities (SMMs) for women with high and low body mass index (BMI), 2021-2024.         

_{Note: Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. * BMI in the overweight (25.0-29.9) or obese (≥30.0) category; **BMI in the underweight (<18.5) or healthy (18.5-24.9) category; ICU/CCU=Intensive care unt/Coronary care unit; SMM risk is per 1,000 maternities; BMI data on maternities were obtained for 118,601 (54.3%) of the 218,398 women who gave birth in a maternity hospital/unit during 2021-2024; Risk ratio compares the risk of SMM among high BMI women relative to the risk among low BMI women.}

Age, parity and body mass index

The risk of SMM was examined separately by age, parity and BMI.

Advanced maternal age was associated with an increased risk of SMM. Compared to women in their early thirties, the risk of SMM was 86% higher among women aged at least 40 years (Table 16).

Regarding parity, women with one previous completed pregnancy had the lowest risk of SMM. Compared to them, the risk was just marginally higher among nulliparous women and women with two previous completed pregnancies, but the risk was increased among women with three or more previous completed pregnancies.

With respect to BMI, women with a BMI in the lean category were at low risk. Compared to them, the risk was greater for women in the overweight BMI category, but women in the obese BMI category had greater than double the risk.

Table 15. Risk of severe maternal morbidity (SMM) by age, parity and BMI, 2023 and 2024.    

_{Note: BMI was not known for 24 women in 2023 and 28 women in 2024. Parity was not known for one woman in 2024. For 2023, data on maternities by BMI were obtained for 30,531 women who gave birth or booked to give birth in one of six of the country’s maternity hospitals/units. This is 56.8% of the 53,371 women who gave birth in 2023, according to the Helathcare Pricing Office (HPO) data. We multiplied the BMI data on 30,531 women by 1.76 (i.e. 100%/56.8%) to estimate the national number of maternities by BMI category. For 2024, data on maternities by BMI were obtained for 32,257 women who gave birth or booked to give birth in one of eight of the country’s maternity hospitals/units. This is 61.5% of the 52,458 women who gave birth in 2024, according to HPO data. We multiplied the BMI data on 32,257 women by 1.63 (i.e. 100%/61.5%) to estimate the national number of maternities by BMI category. The estimated number of maternities were tabulated above and used to calculate the risk of SMM per 1,000 maternities and the risk ratios. Data on the national number of maternities by age and parity for both 2023 and 2024 were provided by the HPO. Exact Poisson 95% confidence intervals were calculated for the risk and risk ratio. Risk ratios compare the risk for each age/parity/BMI group against the risk for the reference group (30-34yrs/Para 1/Lean BMI). Ref. = Reference group.}

Ethnicity

There are no national data available on ethnicity for the pregnant population in Ireland which impedes the calculation of SMM risk per ethnic group. The distribution by ethnic group of the women who experienced SMM in 2023 and 2024 broadly reflected that of the general population of women aged 15-49 years, as reported from the 2022 national census (Table 16).³⁷ There was an over-representation of women whose ethnicity was described as Black, accounting for 12.0% and 5.7% of SMM cases in 2023 and 2024 respectively, compared to 2% of the population aged 15-49 years in this ethnic group. Similarly, women of Asian ethnicity (6.2% and 6.9%) and Irish Traveller (2.1% and 3.2%) were over-represented in experiencing SMM when compared to the percentage of women aged 15-49 years of that ethnic group in the Irish population for the reporting years 2023 and 2024 respectively.

Table 16: Ethnicity of women who experienced SMM, 2023 and 2024.

_{Note: Values are shown as n (%) unless otherwise stated. Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. *Central Statistics Office. (2024). Census of 2022.}

Smoking, alcohol and drug misuse

Smoking status at the time of the first hospital booking appointment was known for 96% of the 697 women. Of these, 8.1% (n=54 of 670) were reported to have been smoking at the time of the first booking. The prevalence of smoking during pregnancy is not routinely published for all Irish pregnancies but a previous study reported values ranging from 14.3 to 10.9% between 2011 and 2015 in a large maternity hospital in Ireland.³⁸ Similarly rates of 8%, 11% and 8% have been reported for England, Scotland and the Netherlands, respectively.^39-41 

Of these 54 women who smoked at time of booking visit, only four were reported to have given up smoking during pregnancy (7.4%, unknown for eight women).

Alcohol drinking status at the time of the first hospital booking appointment was not known for 6.2% of the women (n=43). Of the 654 women with available data, only 0.8% (n=5) self-reported alcohol consumption at the time of their first booking appointment.

Five individuals (0.7%) were recorded as having a documented history of drug abuse or attendance at a drug rehabilitation unit (prior to the pregnancy). Five additional women were reported as using drugs during the pregnancy (0.7%).

Obstetric factors associated with the severe maternal morbidity event

For 15.2% of the women who experienced SMM in 2023 and 2024, their pregnancy was the result of infertility treatment (n=104 of 684, unknown for 13). The method of treatment was specified for all but two of the 104 pregnancies. Of these, 94 pregnancies (90%) were the result of IVF; some of which included egg donation, sperm donation, and the Intracytoplasmic sperm injection (ICSI). A further five pregnancies (5%)) were the result of ovulation induction, and three pregnancies (3%) were the result of Intrauterine insemination (IUI).

Nearly half of women who had previously given birth had previously had a caesarean section (n=186 of 401, 46.4%, unknown for 1 woman).

Gestation at pregnancy-end for women who experienced a SMM ranged from 4 to 42 weeks. For two thirds of the women affected in 2023 and 2024, their pregnancy went full term, i.e. 37-41 weeks' gestation (n=465, 67.6%) (Table 17). For a further 21.2% of women, their pregnancy ended at moderate-to-late pre-term gestation (32-36 weeks), whereas for 5.2%, the end of pregnancy occurred before 22 weeks of gestation (Table 19).

Table 17: Gestation at pregnancy-end for women who experienced severe maternal morbidity (SMM), 2021-2024.

_{Note: Values are shown as n (%) unless otherwise stated; * Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. Gestation at pregnancy-end was not known for one woman in 2021, three women in 2023 and for six women in 2024.}

Severe maternal morbidity associated with early pregnancy loss

Early pregnancy loss (i.e. before 24 weeks of gestation and birthweight less than 500g) was experienced by 48 of the 697 women (6.9%). Fifteen of these 48 women (31%) suffered a miscarriage: 5 early miscarriages (up to 13 weeks' gestation) and 10 late miscarriages (between 13 and 24 weeks of gestation). Ectopic pregnancy was experienced by 27 women (56.3%) and six underwent a termination of pregnancy (12.5%).

Thirty-four of the women who experienced early pregnancy loss were diagnosed with one SMM (3 early miscarriages, 7 late miscarriages, 20 ectopic pregnancies, and 4 terminations of pregnancy (TOP)). Twelve further women were diagnosed with two SMMs, and two woman suffered 3 SMMs

ICU admission was the most frequently reported SMM, associated with 29 of the 48 early pregnancy losses, of which 18 did not experience another SMM as defined by this audit. Of the women admitted to ICU, seven women also experienced MOH, and three women were admitted due to septicaemic shock. MOH was associated with 21 of the 48 early pregnancy losses.

Severe maternal morbidity associated with multiple pregnancy

Of the 697 women who experienced SMM in 2023 and 2024 and had reported obstetric details, 649 had a pregnancy that resulted in the birth of at least one baby. As shown in Table 18, 42 of these women had a multiple birth (n=42 of 649, 6.5%), involving twin and triplet births. In Ireland in 2024, 1.6% of all women delivering in hospital had a multiple birth (n=860 of 52,458). This indicates that multiple birth was more than three times more common in cases of SMM than in all maternities (6.1% versus 1.6%), a reflection of the increased risk of SMM associated with multiple birth. The national SMM rate associated with single birth was 8.13 per 1,000 maternities in 2024, whereas the SMM rate associated with multiple birth was 3.9 times higher at 31.99 per 1,000 maternities, a highly statistically significant difference (p-value <0.001). These findings are similar to findings from Scotland and the Netherlands, reporting a risk of SMM four times higher in twin births when compared to singletons.^8,42

Table 18. Single and multiple births for women who experienced severe maternal morbidity (SMM) but who did not experience early pregnancy loss, 2021-2024.        

_{Note: Values are shown as n(%) unless otherwise stated. Total maternities by plurality were provided by the Healthcare Pricing Office (HPO) data. SMM rate per 1,000 maternities. Exact Poisson 95% confidence intervals were calculated for the rate and rate ratio. Ref. =Reference group. Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024.}

Mode of delivery associated with severe maternal morbidity

The mode of delivery for nearly two thirds of the 649 women giving birth in 2023 and 2024 was caesarean section (65.9%; Table 19). The majority of caesarean sections in cases of SMM were carried out prior to labour (n=288, 67.4%). This may reflect the clinical complexity of the pregnancy rather than indicating that mode of delivery may be influencing the risk of SMM. Thirty-four percent of women had a vaginal delivery, usually spontaneous (24.7% of all deliveries).

Table 19: Primary mode of delivery (excluding those who experienced early pregnancy loss) for women who experienced severe maternal morbidity (SMM), 2021-2024.

_{Note: Data excludes 18, 17, 18 and 30 cases of early pregnancy loss in 2021, 2022, 2023 and 2024 respectively. Values shown are n (%) unless otherwise stated; * Mode of delivery was not known for one case in 2022. For cases of multiple births when the mode of delivery differed for the babies, the more complex mode of delivery was taken as the primary mode. CS= caesarean section}      

12. Level of Care

Practically all the women who experienced SMM in 2023 and 2024 required an increased Level of support/critical care (Table 20). More than half of the women required Level 1 care (59%), while more than a quarter (27%) needed Level 2 Care. A further 8% of women experiencing an SMM required Level 3 Care.

Table 20: Level of care provided to women during severe maternal morbidity (SMM) events in Ireland, 2023 and 2024.

_{Note: Data reported from 18 of 19 maternity units in Ireland in 2023 and 2024. Level of care unknown for 1 woman in 2023 and 1 woman in 2024.}

_{Data reported from 18 of 19 maternity units in Ireland in 2023 and 2024. Level of care unknown for 1 woman in 2023 and 1 woman in 2024.)}

Of all women requiring ICU/CCU admission (n=372), 47% required Level 1 Care, 38% required Level 2 Care and 15% required Level 3 Care in 2023 and 2024. This highlights that admission to an ICU/CCU did not infer that a woman had a requirement for Level 3 Care in 2023 and 2024. This mirrors findings in the NPEC audit on Care of the Critically Ill Woman in Obstetrics in Ireland (2014-2016).²⁰

As previously mentioned, admissions to intensive care can reflect resource issues in cases where women required a higher level of monitoring in small maternity units without HDU facilities.

Of the major obstetric haemorrhage cases recorded in 2023 and 2024, nearly two thirds required Level 1 Care (66%) while 25% required Level 2 Care and nearly 7% required Level 3 Care (Table 21). As expected clinically, higher levels of critical care/monitoring were required for the women experiencing life-threatening maternal morbidities, e.g. all women experiencing acute respiratory dysfunction (defined in this audit as requiring advanced respiratory ventilation) received Level 3 care.

Table 21: Level of care provided to women during specific severe maternal morbidity (SMM) events in Ireland, 2023 and 2024.      

_{Note: More than one morbidity may apply per woman.  % shown refers to level of care per each type of morbidity; ICU=intensive care unit; CCU=coronary care unit. Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024. Level of care unknown for 1 woman in 2023 and 1 woman in 2024.}                  

13. Neonatal Outcomes

Of the 649 SMM cases associated with the birth of a baby, a total of 694 babies were born: 607 singleton births, 39 twin births (78 babies), and 3 triplet births (9 babies).

Information on neonatal outcome, regarding perinatal death, was available for all infants. Of the 694 infants, there were 17 stillbirths, three early neonatal deaths and one late neonatal death. One early neonatal death (4.8%) was born at less than 22 weeks' gestation, and one late neonatal death (4.8%) was born between 22 and 27 weeks' gestation. Six infants (28.6%) were stillborn at 28-31 weeks' gestation. Six stillbirths (28.6%) and one early neonatal death (4.8%) occurred at 32-36 weeks’ gestation. Five stillbirths (23.8%) and one early neonatal death (4.8%) were born at full term (37-41 weeks’ gestation). 

One third of the 21 bereaved mothers experienced major obstetric haemorrhage (n=7, 33.3%). This percentage was 34% in 2021, and 66.7% in 2022.

One early neonatal death occurred in an infant less than 24 weeks gestational age and with a birthweight less than 500 grams. There was also one late neonatal death recorded. To allow for comparison to the national perinatal mortality rate (PMR), these two infants were excluded from the PMR among women experiencing SMM.

The perinatal mortality rate (PMR) based on the 17 stillbirths and two early neonatal deaths (with a birthweight of ≥500g or a gestational age ≥24 weeks at delivery) for 2023 and 2024 was 27.46 per 1,000 births, i.e. 2.7% or 1 in 36 of the infants died. This rate was six times the PMR observed for all births in Ireland in 2023 (p-value <0.001; Table 22). The increased PMR associated with SMM cases in Ireland is consistent with findings from previous SMM audits conducted by NPEC.

Table 22: Perinatal mortality among infants born to women with severe maternal morbidity (SMM) in Ireland in 2023 and 2024 compared to perinatal mortality among all infants born in Ireland in 2023.   

_{Note: PMR=perinatal mortality rate per 1,000 births; Perinatal deaths include infants with a birthweight of ≥500g or a gestational age ≥24 weeks at delivery. Poisson 95% confidence intervals were calculated for the rate and rate ratio. Ref. = Reference group. Data reported from 18 of 19 maternity units in Ireland for 2023 and 2024.⁴³}

Public Representative Message

The fundamental aim of this and previous audits remains unchanged: “to provide a national surveillance of the incidence of women experiencing severe maternal morbidities, to identify quality improvement initiatives and make recommendations for the improvement of maternal care for women in Ireland. Ongoing audit on maternal outcomes is vital to monitor quality and responsiveness of maternity care”.

The NPEC’s objective is to work collaboratively with Irish maternity units so that clinical audit data and epidemiological evidence translate into meaningful improvements in maternity care for women and their families. It is therefore concerning that one significant maternity unit did not submit data for the 2023–2024 audit cycle. This raises important questions. Is the absence of this data linked to the continued non‑implementation of recommendations from this and previous audits? Have protected resources—time, staffing, and clinical support—been secured to ensure accurate and timely reporting?

Protected resources are not optional; they are fundamental. Without them, acute reporting and data recording suffer, and the accuracy of these reports maybe compromised.

The commitment shown by maternity units over the past 12 published reports has driven improvements in clinical management, staff education, and the preparation of women entering the maternity system. The Key Findings of this year’s report again highlight areas where targeted learning can lead to safer, more effective care.

However, the evidence presented within this report can only lead to improved outcomes if it is examined, reviewed, communicated, and acted upon. The value of this audit lies not in its publication, but in the willingness of every maternity unit to engage fully with its findings and to implement the changes required to protect our wives, partners, sisters, mothers and friends.

                                                                                                                                                                       Claire Jones

                                                                                                                                                                                            Patient Representative

                                                                                                                                                                                            NPEC Severe Maternal Morbidity Group                                                                                                                                                    

References

How to cite this report:

Manning E, O'Connell K, Corcoran P, Keane J, Herrera M, Greene RA, on behalf of the Severe Maternal Morbidity Group. Severe Maternal Morbidity in Ireland Annual Report 2023 and 2024. Cork: National Perinatal Epidemiology Centre, 2026.