Maternal Polyphenol Intake and Gestational Hypertension: Nonlinear Associations and Inflammatory Mediation

Gestational hypertension (GH) is a common pregnancy complication associated with long-term cardiovascular risks in both mothers and offspring. Polyphenols, widely present in plant-based foods, exhibit antioxidant and anti-inflammatory properties, but their relationship with GH risk remains insufficiently understood. GH risk remains unclear. This study included 2160 participants from the Tongji Birth Cohort. Dietary intake during early pregnancy was assessed using a validated food frequency questionnaire, and polyphenol intake was estimated using standardized databases. GH was defined as systolic or diastolic blood pressure ≥ 140/90 mmHg after 20 weeks of gestation in previously normotensive women. Multivariable logistic regression and restricted cubic spline analyses demonstrated nonlinear inverse associations between total and subclass-specific polyphenol intake and GH risk, with risk reductions plateauing at moderate-to-high intake levels (approximately 450 mg/day for total polyphenols, 300 mg/day for flavonoids, and 80 mg/day for phenolic acids). Fruit-derived polyphenols contributed most strongly. Mediation analyses indicated that the systemic immune-inflammation index partially mediated the associations of total polyphenols (8.19%) and flavonoids (8.04%) with GH risk. Higher maternal polyphenol intake, particularly from fruits, was associated with lower GH risk, partly mediated by systemic inflammation.