Aspirin use at implantation may improve fecundability

Use of aspirin during the implantation window of the menstrual cycle appears to increase fecundability, reveals a recent study.

Data from a prospective cohort study of women between 30 and 44 years of age, who were trying to conceive naturally from 2008 through 2015, were analysed. Diaries were used to determine medication usage, which was classified as acetaminophen, aspirin or nonaspirin nonsteroidal anti-inflammatory drug, during four time periods of interest (preovulatory, periovulatory and implantation) as well as the overall nonmenstrual bleeding days of the cycle.

Daily diary menstrual bleeding information were used to enumerate menstrual cycles during the prospective attempt to become pregnant. Conception referred to a positive home pregnancy test.

The investigators used discrete time fecundability models to estimate the fecundability ratio (FR) and 95 percent confidence interval (CI) in each time window of interest and for each pain reliever compared with no medication use after adjusting for several covariates included age, race, education, body mass index, alcohol and caffeine use, frequency of intercourse, history or migraines or uterine fibroids.

In 858 women and 2,366 cycles included in this analysis, use of medication was infrequent. Use of nonaspirin nonsteroidal anti-inflammatory drugs or acetaminophen did not correlate with fecundability in any of the time windows of interest.

On the other hand, aspirin use during the implantation window correlated with increased fecundability (adjusted FR, 2.05, 95 percent CI, 1.23–3.41), but this was limited by a small sample size. This association persisted even when analysis was limited to cycles with minimal missing data or when adjusting for gravidity. None of the other medications showed an association with fecundability.

“These results expand previous literature to suggest the following: (1) implantation may be an important target for the effects of aspirin on conception and (2) aspirin may be beneficial, regardless of pregnancy loss history,” the investigators said.