To compare time to pregnancy and live birth among couples with varying intervals of pregnancy loss date to subsequent trying to conceive date.
In this secondary analysis of the Effects of Aspirin in Gestation and Reproduction trial, 1,083 women aged 18–40 years with one to two prior early losses and whose last pregnancy outcome was a nonectopic or nonmolar loss were included. Participants were actively followed for up to six menstrual cycles and, for women achieving pregnancy, until pregnancy outcome. We calculated intervals as start of trying to conceive date minus pregnancy loss date. Time to pregnancy was defined as start of trying to conceive until subsequent conception. Discrete Cox models, accounting for left truncation and right censoring, estimated fecundability odds ratios (ORs) adjusting for age, race, body mass index, education, and subfertility. Although intervals were assessed prior to randomization and thus reasoned to have no relation with treatment assignment, additional adjustment for treatment was evaluated given that low-dose aspirin was previously shown to be predictive of time to pregnancy.
Couples with a 0–3-month interval (n=765 [76.7%]) compared with a greater than 3-month (n=233 [23.4%]) interval were more likely to achieve live birth (53.2% compared with 36.1%) with a significantly shorter time to pregnancy leading to live birth (median [interquartile range] five cycles [three, eight], adjusted fecundability OR 1.71 [95% confidence interval 1.30–2.25]). Additionally adjusting for low-dose aspirin treatment did not appreciably alter estimates.
Our study supports the hypothesis that there is no physiologic evidence for delaying pregnancy attempt after an early loss.
Couples who begin trying to conceive within 3 months compared with greater than 3 months after an early pregnancy loss have a higher probability of achieving a live birth.
Epidemiology Branch, Division of Intramural Population Health Research, and the Program of Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland; and the Division of Public Health, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, Utah.
Corresponding author: Enrique F. Schisterman, PhD, Eunice Kennedy Shriver National Institute of Child Health and Human Development 6100 Executive Boulevard, 7B03, Rockville, MD 20852; e-mail: email@example.com.
Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract Nos. HHSN267200603423, HHSN267200603424, HHSN267200603426).
Financial Disclosure The authors did not report any potential conflicts of interest.
Presented in part at the annual meeting of the Society for Epidemiologic Research, June 16–19, 2015, Denver, Colorado.