Abstract

Background/Objectives: Hypertensive disorders of pregnancy, particularly preeclampsia and eclampsia, are associated with high maternal and fetal morbidity and mortality, with maternal obesity representing a major, modifiable risk factor. This study aimed to estimate the association between obesity and preeclampsia/eclampsia (PEC) in obstetric hospitalizations in the state of São Paulo, Brazil, and to examine risk trends across maternal age groups and between two distinct temporal cohorts. Methods: This population-based observational study analyzed 2,338,934 obstetric hospitalizations using data from the Hospital Information System of the Unified Health System (SIH/SUS). PEC and obesity diagnoses were coded according to the International Classification of Diseases, 10th Revision (ICD-10). Logistic regression models were applied to estimate associations adjusted for maternal age, complemented by adjusted marginal predictions. Results: PEC occurred more than twice as often among women with obesity than without (5.4% vs. 2.2%; OR 2.13, 95% CI 1.84–2.47) and was associated with longer hospital stays (3.52 vs. 2.70 days) and higher costs (R$797.91 vs. R$602.69). The absolute risk difference between obese and non-obese women declined from 24.7% to 13.6% at age 20 between the 2017–2019 and 2023–2025 cohorts, while the relative risk gradient remained stable across all ages. Conclusions: Obesity is strongly associated with increased PEC risk, longer hospitalization, and higher costs. The observed attenuation in absolute risk differences in the most recent cohort reinforces the need for preventive interventions, nutritional surveillance, and public health policies aimed at reducing hypertensive complications during pregnancy for both obese and non-obese women.

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