Intrauterine Fetal Growth Restriction - New Insights into Prenatal Detection, Definition, Surveillance and Delivery

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.

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, EFWpublications, 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.