Preterm, early term, and post-term infants from Riyadh mother and baby multicenter cohort study: The cohort profile

Birth before 37 or beyond 42 gestational weeks is associated with adverse neonatal and maternal outcomes. Studies investigating determinants and outcomes of these deliveries are scarce. The objective of this study was to determine the neonatal birth profile in relation to the gestational age at delivery and to evaluate its influence on the immediate maternal and neonatal outcomes.

This is a multicenter cohort study of 13,403 women conducted in three hospitals in Riyadh. Collected data included sociodemographic characteristics, obstetric history, and physical and laboratory measurements. Regression models were developed to estimate the adjusted odds ratio (OR) and confidence intervals (CI) to determine factors associated with preterm, early term, and post-term births and to evaluate common maternal and neonatal risks imposed by deliveries outside the full term.

The incidence of preterm, early term, and post-term delivery was 8.4%, 29.8%, and 1.4%, respectively. Hypertensive events during pregnancy consistently increased the risk of all grades of preterm births, from more than 3-fold for late preterm (OR = 3.40, 95% CI = 2.21-5.23) to nearly 7-fold for extremely early preterm (OR = 7.11, 95% CI = 2.24-22.60). Early term was more likely to occur in older mothers (OR = 1.30, 95% CI = 1.13-1.49), grand multiparous (OR = 1.21, 95% CI = 1.06-1.38), pregestational diabetes (OR = 1.91, 95% CI = 1.49-2.44), and gestational diabetes women (OR = 1.18, 95% CI = 1.05-1.33). The risk of post-term birth was higher in primiparous. In preterm births, the adverse outcome of neonates having an APGAR score of <7 at 5 min and admission to neonatal intensive care units increased progressively as the gestational age decreased. Post-term births are 2-fold more likely to need induction of labor; meanwhile, preterm births were more likely to deliver by cesarean section.

This large cohort study was the first in Saudi Arabia to assess the delivery profile across a continuum of gestational age and the associated maternal and neonatal adverse outcomes of deliveries outside the full-term period. The study showed that the prevalence of preterm and post-term birth in Saudi Arabia is similar to the prevalence in other high-income countries. The immediate adverse pregnancy outcomes inversely increased with the decrease in gestational age at delivery. In addition, maternal age, hypertension, diabetes, and parity influenced the gestational age at delivery.