Incidence and risk factors for early pregnancy loss in women with first pregnancy undergoing in vitro fertilization-embryo transfer

Background This study aimed to explore the incidence and influencing factors for early pregnancy loss (EPL) in infertility patients with first pregnancy undergoing in vitro fertilization (IVF) embryo transfer cycles in Jilin province, China. Methods A retrospective study of 2709 first pregnancy embryo transfer cycles collected from January 2016 to January 2021 was performed. The cycles were divided into the EPL group (n = 411) and the live birth group (n = 2298) according to the cycle outcomes. Results The EPL rate of the first-time pregnancies for infertility patients undergoing fresh/frozen-thaw embryo transfer cycle was 14.1%. Female patients aged 40 and older had increased odds of EPL compared to those under 35 (OR = 3.97, 95%CI: 2.80-7.55). Female patients with a body mass index (BMI) of 25 or greater were more likely to have EPLs than those in the normal BMI range (OR = 1.32, 95%CI: 1.03-1.70). The odds of EPL after frozen-thaw embryo transfer were higher than those after fresh embryo transfer (OR = 1.59, 95%CI: 1.11-2.27). A thin endometrium on the day of embryo transfer increased the odds of EPL (OR = 1.84, 95%CI: 1.01-3.33). Transferring more than two embryos had lower odds of EPL than single-embryo transfer (OR = 0.67, 95%CI: 0.50-0.90). Compared with other infertility diagnoses, tubal factor alone was associated with lower odds of EPL (OR = 0.72, 95%CI: 0.53-0.98). Conclusions The risk factors for EPL were age 40 and older, obesity, frozen-thaw cycle, thin endometrium, and non-isolated tubal factor.