Impact of a previous late miscarriage on subsequent pregnancy outcomes: A retrospective cohort study over 10 years

To explore the prognostic impact of a previous late miscarriage (LM) on the subsequent pregnancy outcomes of women with infertility.

This retrospective cohort study included couples who had experienced LM following their first embryo transfer during an in vitro fertilization (IVF) cycle from January 2008 to December 2020. Subgroup analysis and binary logistic regression were performed to evaluate the associations between LM due to different causes and subsequent pregnancy outcomes.

A total of 1072 women who had experienced LM were included in this study, comprising 458, 146, 412, and 56 women with LM due to unexplained factors (unLM), fetal factors (feLM), cervical factors (ceLM; i.e. cervical incompetence), and trauma factors (trLM), respectively. Compared with the general IVF (gIVF) population, the early miscarriage rate was significantly higher in the unLM group (8.28% vs. 13.47%, adjusted odds ratio [OR] 1.60, 95% confidence interval [95% CI] 1.12-2.28; P = 0.01). Furthermore, women in the unLM and ceLM groups had a dramatically increased risk of recurrent LM (unLM: 4.24% vs. 9.43%, aOR 1.91, 95% CI 1.24-2.94; P = 0.003; ceLM: 4.24% vs.15.53%, aOR 2.68, 95% CI 1.82-3.95; P < 0.001) and consequently a reduced frequency of live birth (unLM: 49.96% vs. 43.01%, aOR 0.75, 95% CI 0.61-0.91; P = 0.004; ceLM: 49.96% vs. 38.59%, aOR 0.61, 95% CI 0.49-0.77; P < 0.001) compared with the gIVF population.

A previous LM due to an unexplained factor or cervical incompetence was significantly associated with a higher risk of miscarriage and a lower live birth rate after subsequent embryo transfer.