Association Between Early-Pregnancy Mean Arterial Pressure and Onset Timing of Hypertensive Disorders of Pregnancy: A Retrospective Cohort Study in Japan.

Background Mean arterial pressure (MAP) in early pregnancy is a predictor of hypertensive disorders of pregnancy (HDP). However, no studies in Japanese populations have examined the association between MAP and HDP stratified by gestational age at onset. This study aimed to investigate the association between MAP in early pregnancy and gestational age-specific HDP subtypes in a Japanese population. Methods This study included 2,030 Japanese pregnant women. Multinomial logistic regression models were used to investigate the association between MAP in early pregnancy and gestational age-specific HDP subtypes (early-onset, preterm late-onset, and term late-onset). Results Higher MAP in early pregnancy was significantly associated with an increased risk of HDP across all gestational age-specific subtypes. The adjusted odds ratios (95% confidence intervals (CIs)) for early-onset HDP were 1.147 (95% CI: 1.102-1.194), preterm late-onset HDP were 1.105 (95% CI: 1.067-1.145), and term late-onset HDP were 1.077 (95% CI: 1.051-1.105). Conclusions Higher MAP in early pregnancy was associated with an increased risk of HDP, with a stronger association observed for earlier onset.