Fetal and neonatal outcomes of preterm infants born before 32 weeks of gestation according to antenatal vs postnatal assessments of restricted growth.

Background: Fetal growth restriction is defined using ultrasound parameters during pregnancy or as a low birthweight for gestational age after birth, but these definitions are not always concordant.

Objective: The purpose of this study was to investigate fetal and neonatal outcomes based on antenatal vs postnatal assessments of growth restriction.

Study Design: From the EPIPAGE 2 population-based prospective study of very preterm births in France in 2011, we included 2919 singleton nonanomalous infants 24-31 weeks gestational age. We constituted 4 groups based on whether the infant was suspected with fetal growth restriction during pregnancy and/or was small for gestational age with a birthweight <10th percentile of intrauterine norms by sex: 1) suspected with fetal growth restriction/small for gestational age 2) not suspected with fetal growth restriction/small for gestational age 3) suspected with fetal growth restriction/not small for gestational age and 4) not suspected with fetal growth restriction/not small for gestational age. We estimated relative risks of perinatal mortality and morbidity for these groups adjusting for maternal and neonatal characteristics.

Results: We found that 22.2% of infants were suspected with fetal growth restriction/small for gestational age, that 11.4% infants were not suspected with fetal growth restriction/small for gestational age, that 3.0% infants were suspected with fetal growth restriction/not small for gestational age, and that 63.4% infants were not suspected with fetal growth restriction/not small for gestational age. Compared with infants who were not suspected with fetal growth restriction/not small-for-gestational-age infants, small-for-gestational-age infants suspected and not suspected with fetal growth restriction had higher risks of stillbirth or termination of pregnancy (adjusted relative risk, 2.0 [95% confidence interval, 1.6-2.5] and adjusted relative risk, 2.8 [95% confidence interval, 2.2-3.4], respectively), in-hospital death (adjusted relative risk, 2.8 [95% confidence interval, 2.0-3.7] and adjusted relative risk, 2.0 [95% confidence interval, 1.5-2.8], respectively), and bronchopulmonary dysplasia (adjusted relative risk, 1.3 [95% confidence interval, 1.2-1.4] and adjusted relative risk, 1.3 [95% confidence interval, 1.1-1.4], respectively), but not severe brain lesions. Risks were not increased for infants suspected with fetal growth restriction but not small-for-gestational-age.

Conclusion: Antenatal and postnatal assessments of fetal growth restriction were not concordant for 14% of very preterm infants. In these cases, birthweight appears to be the more relevant parameter for the identification of infants with higher risks of adverse short-term outcomes.