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Updated: May 12, 2026
Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction
Published on: June 29, 2013
Optimizing the definition of intrauterine growth restriction: the multicenter prospective PORTO Study
Julia Unterscheider1, Sean Daly, Michael Patrick Geary
1Department of Obstetrics and Gynecology, Royal College of Surgeons in Ireland, Dublin, Ireland. juliaunterscheider@rcsi.ie
Insights
Abnormal umbilical artery Doppler and estimated fetal weight below the 3rd centile are key indicators of adverse perinatal outcomes in pregnancies with fetal growth restriction. These findings suggest current definitions of intrauterine growth restriction may need re-evaluation for improved clinical management.
Area of Science:
- Perinatal medicine
- Fetal development
- Neonatal outcomes
Background:
- Intrauterine growth restriction (IUGR) affects fetal development and is associated with increased perinatal morbidity and mortality.
- Current definitions of IUGR, often based on estimated fetal weight (EFW) below the 10th centile, may not accurately identify all at-risk pregnancies.
- Sonographic findings and umbilical artery Doppler assessments are crucial for evaluating fetal well-being in IUGR.
Purpose of the Study:
- To identify sonographic markers associated with perinatal morbidity and mortality in pregnancies with fetal growth restriction.
- To evaluate the effectiveness of various IUGR definitions in predicting adverse perinatal outcomes.
- To inform potential revisions of IUGR diagnostic criteria and management strategies.
Main Methods:
- A prospective, observational, multicenter study (PORTO Study) involving over 1100 singleton pregnancies with EFW <10th centile.
- Utilized diverse IUGR definitions, including EFW and abdominal circumference <10th, <5th, or <3rd centiles, with or without oligohydramnios and abnormal umbilical artery Doppler.
- Documented composite adverse perinatal outcomes, including intraventricular hemorrhage, hypoxic ischemic encephalopathy, necrotizing enterocolitis, sepsis, and death.
Main Results:
- Abnormal umbilical artery Doppler was significantly associated with adverse perinatal outcomes, independent of EFW or abdominal circumference measurements.
- Estimated fetal weight (EFW) <3rd centile was the only sonographic weight-related definition consistently linked to adverse outcomes, with all mortalities occurring in this group.
- Oligohydramnios became clinically significant when present with EFW <3rd centile, further increasing the risk of adverse outcomes.
Conclusions:
- Abnormal umbilical artery Doppler and EFW <3rd centile are strong predictors of adverse perinatal outcomes.
- The findings challenge the adequacy of current IUGR definitions and suggest a need for stricter criteria.
- Further research is warranted to explore the impact of revised IUGR cutoffs on pregnancy outcomes and resource allocation.
Objective:
The objective of the Prospective Observational Trial to Optimize Pediatric Health in Intrauterine Growth Restriction (IUGR) (PORTO Study), a national prospective observational multicenter study, was to evaluate which sonographic findings were associated with perinatal morbidity and mortality in pregnancies affected by growth restriction, originally defined as estimated fetal weight (EFW) <10th centile.
Study Design:
Over 1100 consecutive ultrasound-dated singleton pregnancies with EFW <10th centile were recruited from January 2010 through June 2012. A range of IUGR definitions were used, including EFW or abdominal circumference <10th, <5th, or <3rd centiles, with or without oligohydramnios and with or without abnormal umbilical arterial Doppler (pulsatility index >95th centile, absent or reversed end-diastolic flow). Adverse perinatal outcome, defined as a composite outcome of intraventricular hemorrhage, periventricular leukomalacia, hypoxic ischemic encephalopathy, necrotizing enterocolitis, bronchopulmonary dysplasia, sepsis, and death was documented for all cases.
Results:
Of 1116 fetuses, 312 (28%) were admitted to neonatal intensive care unit and 58 (5.2%) were affected by adverse perinatal outcome including 8 mortalities (0.7%). The presence of abnormal umbilical Doppler was significantly associated with adverse outcome, irrespective of EFW or abdominal circumference measurement. The only sonographic weight-related definition consistently associated with adverse outcome was EFW <3rd centile (P = .0131); all mortalities had EFW <3rd centile. Presence of oligohydramnios was clinically important when combined with EFW <3rd centile (P = .0066).
Conclusion:
Abnormal umbilical artery Doppler and EFW <3rd centile were strongly and most consistently associated with adverse perinatal outcome. Our data call into question the current definitions of IUGR used. Future studies may address whether using stricter IUGR cutoffs comparing various definitions and management strategies has implications on resource allocation and pregnancy outcome.
