A secondary analysis of a prospective cohort study: association between aspirin regime and early- and late-onset preeclampsia.

backgroundPreeclampsia (PE) poses a threat to maternal and perinatal health. Low-dose aspirin prophylaxis is recommended for women at high risk of developing PE. Here, we investigated how aspirin regimens and maternal characteristics in early pregnancy are associated with early- and late-onset PE.

methodsThis was a retrospective secondary analysis of prospective cohorts. A total of 975 participants who registered and delivered at Beijing Obstetrics and Gynecology Hospital between the 1st of January 2023 and the 30th of June 2024 were divided into three groups: non-PE, early-onset PE, and late-onset PE. Univariate and multivariate logistic regression analyses were used to identify risk factors for early- and late-onset PE, as validated using propensity score matching. The optimal duration of medication was determined using receiver operating characteristic curves.

resultsNo significant differences were observed among the groups with respect to maternal age, gravidity, parity, gestational weight gain (GWG), mode of conception, aspirin initiation, or dosage. Aspirin dosage and GWG were not significantly associated with the occurrence of early- and late-onset PE (P>0.05). Multivariate logistic regression analyses, performed prior to PSM, demonstrated maternal pre-pregnancy BMI (adjusted odds ratio [OR] (95% confidence interval [CI]): 1.102(1.028–1.181), P = 0.006) and gestational age at delivery (0.552(0.489–0.623), <0.001) were independent risk factors for early-onset PE; and maternal pre-pregnancy BMI (1.102(1.068–1.136), <0.001), gestational age at delivery (0.854(0.781–0.933), <0.001) and medication duration (1.024(1.000–1.049), 0.046) were identified as independent risk factors for late-onset PE. The optimum medication duration threshold for late-onset preeclampsia occurrence was 22.5 weeks, but this threshold was population-specific and exploratory.

conclusionsOur findings do not suggest an association between different aspirin dosages and the occurrence of PE, nor show an association between GWG and the occurrence of PE. Pre-pregnancy BMI was an independent risk factor for the occurrence of PE, providing a basis for individualized perinatal care and PE risk assessment. Meanwhile, longer medication duration was statistically associated with a higher incidence of late-onset PE in this cohort; however, this finding may reflect residual confounding or marginal effect and requires confirmation in prospective studies.