Early initiation of low-dose aspirin for reduction in preeclampsia risk in high-risk women: a secondary analysis of the MFMU High-Risk Aspirin Study

OBJECTIVE: Early initiation of low-dose aspirin (LDA) may reduce preeclampsia risk. We sought to determine whether LDA was beneficial when initiated < 17w0d, within a trial of high-risk women enrolled < 26w0d. STUDY DESIGN: Secondary analysis of the Maternal-Fetal Medicine Units High-Risk Aspirin study, including women enrolled < 17w0d, randomized to LDA (60 mg day(-1)) or placebo with chronic hypertension (CHTN, n = 186), diabetes (n = 191) or prior preeclampsia (n = 146). The primary outcome was preeclampsia at any time in pregnancy, secondary outcomes were early preeclampsia (<34w0d), late preeclampsia (>= 34w), small for gestational age (SGA; neonatal birthweight < 10th %) and composite (early preeclampsia or SGA). Outcomes were compared by exact chi(2)-tests. RESULTS: Baseline characteristics were similar between treatment groups. Aspirin was associated with a lower rate of late-onset preeclampsia >= 34w (17.36% vs 24.42%, P = 0.047), with a 41% reduction in women with CHTN (18.28% vs 31.18%, P = 0.041). There were no other significant differences in the outcome. CONCLUSION: Aspirin initiated <17w0d reduced the risk for late-onset preeclampsia by 29% supporting the practice of early initiation of aspirin in high-risk women.