Maternal birth weight as an indicator of early-onset and late-onset hypertensive disorders of pregnancy: The Japan Environment and Children's study

Objectives: This study aimed to investigate the association between maternal birth weight (MBW) and hypertensive disorders of pregnancy (HDP) according to the gestational age when HDP develops. Study design: A total of 77,345 subjects were included in this prospective birth cohort study. The association between MBW and HDP was investigated by a multinomial logistic regression model. Main outcome measures: Early-onset HDP (EO-HDP), preterm late-onset HDP (preterm LO-HDP), and term late-onset HDP (term LO-HDP). Results: Lower MBW was associated with higher odds of preterm and term LO-HDP (p-values for trend < 0.0001 and = 0.0005, respectively). A linear association between MBW and EO-HDP was observed (p-values for trend = 0.0496). The shape of the association between MBW and preterm LO-HDP was a combination of the associations between MBW with EO-HDP or LO-HDP. The effect size of the association between MBW < 2,500 g and EO-HDP was lower than that of MBW < 2,500 g with preterm or term LO-HDP. The adjusted odds ratios for EO-HDP, preterm LO-HDP, and term LO-HDP in subjects with MBW < 2,500 g were 1.052 (95 % confidence interval [CI]: 0.665–1.664), 1.745 (95 % CI: 1.220–2.496), and 1.496 (95 % CI: 1.154–1.939), respectively. Conclusions: MBW was associated with HDP, regardless of gestational age when HDP developed. Furthermore, the association of MBW < 2,500 g with preterm or term LO-HDP was stronger than that with EO-HDP.