Objective
To compare time to pregnancy and live birth among couples with varying intervals of pregnancy loss date to subsequent trying to conceive date.
Methods
In this secondary analysis of the Effects of Aspirin in Gestation and Reproduction trial, 1,083 women, aged 18–40 years with 1–2 prior early losses and whose last pregnancy outcome was a non-ectopic or non-molar 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 (OR) adjusting for age, race, BMI, education, and subfertility. While 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.
Results
Couples with a 0–3 month (n=765 [76.7%]) versus >3 month (n=233 [23.4%]) interval were more likely to achieve a live birth (53.2% versus 36.1%) with a significantly shorter time to pregnancy leading to live birth (median (IQR) 5 cycles (3, 8), adjusted fecundability OR: 1.71 [95% CI: 1.30, 2.25]). Additionally adjusting for low-dose aspirin treatment did not appreciably alter estimates.
Conclusion
Our study supports the hypothesis that there is no physiological evidence for delaying pregnancy attempt after an early loss.