The outcome of trisomy 18 pregnancies following the legalisation of termination of pregnancy

Our study of Trisomy 18 in pregnancy found that earlier referral to fetal medicine services enabled decision-making around whether to terminate or continue pregnancy. The findings support universal access to first trimester prenatal aneuploidy screening and both care options.


Hadas Miremberg, Carolina Uribe, Keelin O'Donoghue

Journal Name
Irish Medical Journal
Journal Article
Fatal fetal anomaly, Fetal anomaly, Termination of pregnancy, Termination of pregnancy for fetal anomalies
Full Citation

Miremberg H, Uribe C, O'Donoghue K. The outcome of trisomy 18 pregnancies following the legalisation of termination of pregnancy. Irish Medical Journal. 2023;116(10):P873.

Link to Publication


Termination of pregnancy (TOP) became legal in Ireland in 2019; this included conditions likely to lead to the death of the fetus, making TOP for 'fatal fetal anomaly' (FFA) an option. Trisomy 18 (T18), where the fetus carries three rather than two chromosomes 18s, is associated with major structural or physical anomalies and is usually referred to as a fatal or lethal syndrome. We examined T18 pregnancy decisions and outcomes following the legalisation of TOP for FFA. We identified all pregnancies diagnosed with T18 from 2019-2022, through the fetal medicine referral database at our hospital. We identified forty-seven T18 pregnancies in these 4 years. In 59.6% (28/47) pregnancies, TOP was performed. 18 weeks was the most common time in pregnancy at which TOP was done (range;17-22 weeks). In 11/47 cases, a fetal death occurred in the womb in the second trimester (range; 13.2-18 weeks) of pregnancy, and parental decision-making was unclear at that stage in some of those pregnancies. Parents choosing to continue pregnancy represented 17% (8/47) of the cohort we studied, with six women having their babies at term. Parents choosing TOP were referred to fetal medicine services at a significantly earlier gestational age when compared to those who chose to continue the pregnancy (14 weeks vs. 21.5 weeks, p<0.010; respectively). Following a T18 diagnosis, parents may choose to continue or terminate the pregnancy, with both care options now available in Ireland. Universal access to first trimester prenatal screening for chromosomal aneuploidy, available privately in Ireland already, would facilitate wider and earlier parental choice and decision-making.

Pregnancy Loss Research Group

Pregnancy Loss Research Group, Department of Obstetrics & Gynaecology, University College Cork, Fifth Floor, Cork University Maternity Hospital, Wilton, Cork, T12 YE02, Ireland,