Aspirin use during pregnancy and hypertensive disorders in women with various risks

It is still unclear how well aspirin performs in women with different risks and how the timing of aspirin use influences its efficacy. This study was to evaluate the association between timing of aspirin exposure and hypertensive disorders in pregnant women with various risks in a prospective cohort.

We used data from the Collaborative Perinatal Project, U.S., 1959-1976. Women were grouped into high, moderate and low risks based on medical history. We classified the timing of aspirin exposure into 4 weeks before the last menstrual period, the first, second and third trimesters.

A total of 50,579 pregnant women were included in our analysis with 6453, 18,552 and 25,574 women at high, moderate and low risks, respectively. In high-risk women, aspirin use for more than 7 days in the first trimester reduced the risks of preterm and term preeclampsia/eclampsia by 42% (adjusted OR 0.58; 95% CI 0.36-0.94) and 24% (adjusted OR 0.76; 95% CI 0.59-0.97), respectively; in moderate-risk women, aspirin use for more than 7 days during the third trimester reduced the risks of term preeclampsia/eclampsia and gestational hypertension by 37% (adjusted OR 0.63; 95% CI 0.50-0.79) and 27% (adjusted OR 0.73; 95% CI 0.62-0.86), respectively.

Aspirin use in pregnancy reduces the risks of maternal hypertensive disorders. Early initiation of aspirin in high-risk women was associated with lower incidence of preeclampsia/eclampsia. Meanwhile, the protective effect of aspirin on term preeclampsia/eclampsia and gestational hypertension may continue till late pregnancy.