Background: Hypertensive disorders of pregnancy (HDP) are linked to excessive maternal weight and frequent snoring. However, pathways between maternal excessive weight, pregnancy-onset snoring, and HDP are only partially estimated. We examined and quantified the total and direct associations between excessive maternal weight and incident HDP and their indirect pathway through pregnancy-onset snoring.
Methods: Third trimester pregnant women enrolled from prenatal clinics of a large tertiary medical center. Sleep data were collected through a questionnaire. Demographic and pregnancy information and first trimester maternal weight were abstracted from medical charts. After exclusion of women with prepregnancy hypertension and/or chronic snoring, causal mediation analysis was used to estimate the total and direct association between maternal weight and incident HDP and their indirect association through pregnancy-onset snoring. The proportion of the mediated association through pregnancy-onset snoring from the total association of maternal weight and HDP was also quantified.
Results: After excluding those with chronic hypertension and/or snoring, the final sample included 1,333 pregnant women. In adjusted analysis, excessive maternal weight was directly associated with incident HDP; odds ratio (OR) = 1.87 (95% confidence interval (CI) 1.30, 2.70). Pregnancy-onset snoring significantly mediated the association between maternal weight and incident HDP; OR = 1.08 (95% CI 1.01, 1.17). The mediated pathway accounted for 15% of the total association between maternal weight and incident HDP.
Conclusions: Pregnancy-onset snoring mediates the association between maternal weight and incident HDP in women without prepregnancy snoring or hypertension. These findings demonstrate the relative contributions of excessive maternal weight and pregnancy-onset snoring to incident HDP.