Extrauterine growth restriction in very preterm infant: etiology, diagnosis, and 2-year follow-up

Abstract

In very-preterm small-for-gestational-age (SGA) infants, long-term postnatal growth is confused with extrauterine growth restriction (EUGR). We aimed to document EUGR in SGA infants and in non-SGA infants ("true-EUGR") and its relationship with fetal, maternal, and neonatal etiological factors. Four hundred seventy-nine very-preterm infants (< 32 weeks) born between 2003 and 2014 and attending the follow-up clinic were included. INTERGROWTH-21st preterm postnatal growth standards in conjunction with WHO Child Growth Standards were used to judge the postnatal growth patterns. EUGR was defined as weight < 10th percentile according to the sex at 36-34 weeks postmenstrual age, usually at discharge. Catch-up was evaluated at 2-2.5 years. Low-weight-for-age (wasting), low-length-for-age (stunting), and low-head-circumference-for-age were diagnosed if the z-scores were below - 2 SD. Logistic regression analysis estimated the association between the risk factors and EUGR, according to the SGA status at birth. Overall, EUGR occurred in 51% at 36-34 postmenstrual weeks and 21% at 2-2.5 years. However, among 411 non-SGA infants, "true-EUGR" rates were 43% and 15%, respectively.Conclusion: By 2-2.5 years of age, a "true-EUGR" of 15% can be expected and only the head circumference normalizes in SGA infants. Low birth weight, hyaline membrane disease, bronchopulmonary dysplasia, and male sex were associated with "true-EUGR." What is Known: • Fetal, neonatal, or postnatal charts have been considered to monitor the postnatal growth of preterm infants. • This selection influences the diagnosis of "extrauterine growth restriction" (EUGR) and the clinical strategies used. What is New: • Extrauterine growth restriction (EUGR) in small-for-gestational-age (SGA) infants can not be considered a true EUGR but a postnatal evolution of fetal growth restriction. • Preeclampsia, low gestational age, severe neonatal morbidity and male sex are independently associated with EUGR in non-SGA infants (named "true-EUGR"), which can be expected in 15% of very preterm infants by 2-2.5 years of age.

Keywords: Extrauterine growth restriction; Growth; Growth curves; Preterm infant; Small-for-gestational-age infant.