Association between gestational age-specific weight gain in pregnancy and risk of adverse perinatal outcomes: a secondary analysis of the INTERBIO-21st Fetal Study

<h4>Background</h4>Gestational weight gain (GWG) is a potentially modifiable factor that can influence perinatal health outcomes.<h4>Objectives</h4>This study aims to investigate the association between gestational age (GA)-specific weight gain and adverse perinatal outcomes.<h4>Methods</h4>This study is a secondary analysis of the INTERBIO-21st Fetal Study, a prospective, longitudinal cohort conducted from 8 February, 2012 to 30 November, 2019, across 6 sites in Brazil, Kenya, Pakistan, South Africa, Thailand, and the United Kingdom. A total of 3354 pregnant females, aged ≥18 y with a body mass index (BMI) <35 kg/m², initiated antenatal care before 14 wk of gestation. Weight was measured at 5 ± 1 wk intervals from 14 to 40 wk. GWG was assessed using the GA-specific INTERGROWTH-21st and BMI-specific Institute of Medicine (IOM) guidelines. Adverse outcomes included gestational diabetes mellitus (GDM), pregnancy-induced hypertension (PIH), emergency cesarean delivery, low birthweight (LBW), preterm birth, small or large for gestational age (SGA), macrosomia, and birth length or head circumference (HC) <10th or >90th centile.<h4>Results</h4>Inadequate GWG was prevalent, with 53% (n = 1767) below the 25th centile of INTERGROWTH-21st standards and 62% (n = 2079) below IOM guidelines. Compared with GWG between 25th and 75th centile (n = 370), females with GWG <25th centile (n = 1767) had a higher odds of SGA [odds ratio (OR) = 2.7, 95% confidence interval (CI): 2.2, 3.4], birth HC < 10th centile (OR: 2.4, 95% CI: 1.8, 3.2), GDM (OR: 1.9, 95% CI: 1.3, 2.7), LBW (OR: 1.9, 95% CI: 1.5, 2.4), and birth length <10th centile (OR: 1.7, 95% CI: 1.4, 2.1). Similarly, females with GWG >75th centile (n = 458) had higher odds for emergency cesarean section (OR: 1.7, 95% CI: 1.1, 2.7) and PIH (OR: 1.5, 95% CI: 1.1, 1.9).<h4>Conclusions</h4>Appropriate-for-age-specific GWG between the 25th and 75th centiles standards is associated with reduced adverse outcomes, highlighting the importance of tailored guidelines for optimal maternal and neonatal health.