Benchmark problems for robust control design

BACKGROUND: After early pregnancy loss (EPL), couples often seek counselling on how long to wait before attempting to conceive again. However, the optimal interpregnancy interval (IPI) between EPL and the next pregnancy is controversial. Additionally, studies on the impact of the IPI following a previous EPL on the population with infertility are rare. Here, we explore the relationship between the IPI after EPL and pregnancy outcomes after subsequent frozen embryo transfer (FET). METHODS: In total, 859 patients were included in this retrospective study. Among these, 87 women (10.1%) had an IPI of less than 3 months, 402 (46.8%) had an IPI of 3 to 6 months, 279 (32.5%) had an IPI of 6 to 12 months, and 91 (10.6%) had an IPI of more than 12 months. The baseline characteristics of the four groups were compared and analyzed. Binary logistic regression analyses were subsequently conducted to investigate the association between the IPIs after EPL and pregnancy outcomes after subsequent FET. RESULTS: The live birth rates of the four groups were 41.4%, 41.5%, 36.9% and 28.6%, respectively. There were no significant differences in live birth, biochemical pregnancy, clinical pregnancy, clinical pregnancy loss, or preterm birth among the four groups ( CONCLUSIONS: The results of this study suggest that a short IPI following the return of menstruation did not appear to be significantly associated with adverse pregnancy outcomes. However, prolonging the IPI beyond 12 months might correlate with a reduced likelihood of achieving a live birth, although further research is needed to confirm this observation.