Skip to main content


Close up of pink blossoming tree in spring garden


PORTO: Prospective Observational Trial to Optimise Paediatric Health in growth restricted fetuses

What was this project about?

PORTO: Prospective Observational Trial to Optimise Paediatric Health in growth restricted fetuses

Fetal growth restriction (FGR) is a common complication of pregnancy. Data presented in this thesis, which mainly originate from the national multicentre Prospective Observational Trial to Optimise Paediatric Health in IUGR (PORTO) study, consolidate knowledge in FGR, and contribute new insights into this important clinical problem. For the purpose of this study, FGR was defined as estimated fetal weight (EFW) below the 10th centile for gestation based on population standards.

What was involved?

Contemporary practice was initially evaluated through survey and confirmed the inconsistencies in definition and management of pregnancies with FGR among Irish obstetricians. The PORTO study recruited 1,116 non-anomalous fetuses with EFW <10th centile; 1 in 20 infants (n=57) was affected by adverse perinatal outcome and 1 in 4 infants (n=312) required admission to neonatal intensive care. The objective of the primary analysis was to optimise the definition of FGR using population and customised standards and by analysing growth trajectories. Pregnancies at increased risk of adverse outcome were those with abnormal umbilical artery (UA) Doppler, EFW <3rd centile and decelerative growth patterns. The second objective was to evaluate longitudinal multi-vessel Doppler changes in FGR fetuses to establish whether a predictable sequence really existed. In contradiction to other publications, data showed that there was no single predominant pattern of Doppler deterioration occurring in one fetus over time. UA Doppler was found to be the most important vessel to inform perinatal outcome. Additional analyses focused on delivery outcomes and clinical decision making in FGR which showed that clinicians used ultrasound information to indicate delivery in 77% of cases. Evaluation of placental injuries in FGR identified villous developmental abnormalities as the most common lesion in infants with adverse perinatal outcome.

Finally, this work was used to formulate an evidence-based care standard for FGR pregnancies in Ireland which resulted in the development of the first national clinical practice guideline on FGR. Together with published studies from the PORTO results, the guideline provides clinicians with evidence to improve and consolidate their current standard of care.

Who was involved?

Project team

Name Affiliation Role
Dr Julia Unterscheider Pregnancy Loss Research Group; Royal College of Surgeons in Ireland (RCSI) Dublin  PhD Student
Professor Keelin O'Donoghue Pregnancy Loss Research Group  Supervisor; PI for PORTO at CUMH site 
Professor Fergal Malone RCSI Dublin Primary Supervisor

Dissemination activities

Journal articles

  • Unterscheider J, Horgan R, O'Donoghue K, Greene R. Reduced fetal movements. The Obstetrician & Gynaecologist. 2009;11:245-251.

  • Unterscheider J, O'Donoghue K, Daly S, Geary MP, Kennelly MM, McAuliffe FM, Hunter A, Morrison JJ, Burke G, Dicker P, Tully EC, Malone FD. Fetal growth restriction and the risk of perinatal mortality-case studies from the multicentre PORTO study. BMC Pregnancy and Childbirth. 2014;14:63.

  • Unterscheider J, Daly S, Geary MP, Kennelly MM, McAuliffe FM, O'Donoghue K, Hunter A, Morrison JJ, Burke G, Dicker P, Tully EC, Malone FD. Definition and management of fetal growth restriction: a survey of contemporary attitudes. European Journal of Obstetrics, Gynecology, and Reproductive Biology. 2014;174:41-5.

  • Unterscheider J, O'Donoghue K, Malone FD. Guidelines on fetal growth restriction: a comparison of recent national publications. American Journal of Perinatology. 2015;32(4):307-16.

  • Cody F, Unterscheider J, Daly S, Geary MP, Kennelly MM, McAuliffe FM, Morrison JJ, O’Donoghue K, Hunter A, Dicker P, Tully E, Fhearaigh RN, Malone FD, The Perinatal Ireland Research Consortium. Dynamic growth changes in fetal growth restriction using serial ultrasonographic biometry and umbilical artery doppler: The multicenter PORTO study. International Journal of Gynaecology & Obstetrics. 2022.

Clinical guideline

  • Unterscheider J, O'Donoghue K, Malone F. Clinical Practice Guideline: Fetal Growth Restriction - Recognition, Diagnosis & Management. Version 1.1. Institute of Obstetricians and Gynaecologists, Royal College of Physicians of Ireland and the Clinical Strategy and Programmes Division, Health Service Executive. March 2014.

Book chapter

  • Unterscheider J, O’Donoghue K. Reduced fetal movements. In Sifakis S and Vrachnis N, eds. From Preconception to Postpartum. In Tech; 2012:207-220.

Project status

Completed: 2010 to 2014

Further information

Please email Professor Keelin O’Donoghue:


The PORTO Study was conducted by Perinatal Ireland, a nationwide collaborative research network composed of the seven largest academic obstetric centers in Ireland. The study was funded by the Health Research Board of Ireland and Friends of the Rotunda.

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,