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Preconception low-dose aspirin well tolerated in women, fetuses

Taking low doses of aspirin preconception appears to be well tolerated among women attempting to conceive, those who become pregnant and their fetuses, according to data published in Obstetrics and Gynecology; however, rare and serious complications cannot be ruled out.

“Given the benefits of low-dose aspirin on preeclampsia and potentially other reproductive outcomes, there may be increasing interest in initiating this widely available and low-cost therapy before conception, even among women with a low risk of developing preeclampsia,” Katherine A. Ahrens, PhD, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, in Rockville, Maryland, and colleagues wrote. “Therefore, evaluation of maternal and fetal and neonatal complications and safety associated with preconception low-dose aspirin use in low-risk women is critical and timely.”

To determine the safety and potential complications of low-dose aspirin in women preconception, the researchers conducted a secondary analysis of the Effects of Aspirin in Gestation and Reproduction trial. The trial was a multicenter, block-randomized, double-blind, placebo-controlled study evaluating the effect of low-dose aspirin on the incidence of live birth. A sample of 1,228 U.S. women aged 18 to 40 years with a history of one to two pregnancy losses, who were trying to conceive, were randomly assigned to receive 81 mg of aspirin daily or placebo.

Follow-ups were conducted through six menstrual cycles, or through gestation if they became pregnant. Possible aspirin-related symptoms and emergency care visits were noted at each follow-up meeting. Complications among participants and their fetuses were also collected through case report forms, interviews during and after pregnancy, and medical records.

According to the researchers, the rate of women with at least one possible aspirin-related symptom was similar across both groups, with 74% in the aspirin group and 73% in the placebo group (P = .65). The proportions with at least one emergency care visit were also similar, with 17% in the aspirin group and 16% in the placebo group. With the exception of vaginal bleeding, which occurred in 22% of women in the aspirin group compared with 17% among those who received a placebo (P = .02), maternal complications were evenly distributed among both groups. The distribution of fetal and neonatal complications was also similar. They included three stillbirths, three neonatal deaths and 10 neonates with birth defects.

“With such low and varied incidences of maternal and fetal complications to consider, large registries and meta-analyses will be needed to assess the risk of yet unknown rare but serious complications in ongoing clinical-use cohorts and additional studies, respectively,” Ahrens and colleagues wrote. “Future analyses should also consider preconception compared with postconception initiation of therapy separately.” – by Jason Laday

Disclosure: The researchers report no relevant financial disclosures.