Objective: To perform a meta-analysis determining the association of low-dose aspirin treatment with subsequent abruptio placentae or perinatal mortality.
Data sources: Studies were identified and selected using the MEDLINE bibliographic data base of entries from January 1985 through April 1994. In addition, a manual search was performed using the references from all retrieved reports, review articles, and chapters from textbooks.
Methods of study selection: Three criteria were used to select studies for inclusion: 1) Studies were designed as randomized or double-blind clinical trials; 2) aspirin was administered in doses of less than 200 mg/day; and 3) outcome data included the incidence of abruptio placentae and perinatal mortality. Three studies did not report the occurrence of abruptio placentae, but the authors of those papers answered written requests for such data. A total of 11 studies met our inclusion criteria.
Data extraction and synthesis: We independently evaluated the study methods for each trial and abstracted quantitative outcome data. For each outcome, relative risk, risk differences, and 95% confidence intervals were calculated. The diagnosis of abruptio placentae was taken as self-reported in each trial. No trial of low-dose aspirin in pregnancy had predefined criteria for the diagnosis of abruptio placentae, and abruption was not a primary outcome in any of the 11 trials. We combined data from all studies and compared the data from the randomized trials to those from the double-blind studies.
Conclusion: We found no increased risk for abruptio placentae or increased perinatal mortality in women taking low-dose aspirin.