Morbidity and Mortality in Small-for-Gestational-Age Infants: A Secondary Analysis of Nine MFMU Network Studies

Objective To compare the neonatal morbidity and mortality among small-for-gestational-age (SGA; birth weight < 10% for estimated gestational age [EGA]) versus appropriate-for-gestational-age (AGA; birth weight at 10-89%) newborns. Methods Data from nine Maternal-Fetal Medicine Units Network studies were used and included nonanomalous singletons at 24 weeks or more and birth weight < 90% for EGA. Using multivariable analysis, we compared the morbidity and mortality between SGA and AGA. Random-effect logistic regressions were utilized with adjustment for 10 variables. Results Among the nine studies 71,744 singletons met the inclusion criteria, with 13% (n = 9,415) SGA and 87% (n = 62,329) AGA. Among SGA, the likelihood of stillbirth (8.8 vs. 2.5 per 1,000 births; adjusted odds ratio [aOR] 3.98, 95% confidence interval [CI]: 2.92-5.42) and neonatal mortality (14.0 vs. 5.5 per 1,000 births; aOR 3.18, 95% CI: 2.55-3.95) was threefold higher compared with AGA. For the subgroup of newborns of EGA of 32 weeks or more, SGA, compared with AGA, had significantly higher risk of stillbirth (aOR 3.32, 95% CI: 2.16-5.12) and neonatal mortality (aOR 2.50; 95% CI: 1.38-4.54). From 35 weeks onward, the risk of stillbirth among SGA is almost four times higher than for AGA. Conclusion The risk of stillbirth and neonatal mortality is significantly higher with SGA than with AGA. Modification in practice or new management schema may be warranted.