Perinatal outcome of pregnancies complicated with extreme birth weights at term

The objective of this study is to investigate whether an abnormal birthweight at term, either small for gestational age (SGA, < 5th centile for gestational age) or large for gestational age (LGA, > 95th centile for gestational age), is a risk factor for perinatal complications as compared with birthweight appropriate for gestational age (AGA).

A population-based retrospective cohort analysis of all singleton pregnancies delivered between 1991 and 2014 at Soroka Medical Center. Congenital malformations and multiple pregnancies were excluded. A multivariable generalized estimating equation regression model was used to control for maternal clusters and other confounders.

During the study period, 228,242 births met the inclusion criteria, of them 91% were AGA (n = 207,652), 4.7% SGA, and 4.3% LGA. SGA significantly increased the risk for perinatal mortality (aOR 5.6, 95%CI 4.5-6.8) and low 5-min Apgar scores (aOR 2.2, 95%CI 2.0-2.4), while LGA did not. SGA and LGA were both significant risk factors for cesarean delivery. LGA was significantly associated with shoulder dystocia and post-partum hemorrhage (aOR =13.6, 95%CI 10.9-17.0, and aOR 1.7, 95%CI 1.2-2.6, respectively).

Extreme birthweights at term are significantly associated with adverse maternal and neonatal outcomes. As opposed to SGA, LGA is not independently associated with perinatal mortality.