Uterine niche is associated with adverse in vitro fertilization and intracytoplasmic sperm injection outcomes: a retrospective cohort study

Abstract

To investigate the relationship between uterine niche and reproductive outcomes of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). A retrospective cohort study in the Reproductive Medicine Center of Tongji Hospital, Wuhan, China. A total of 2449 women with cesarean section history who underwent 2874 IVF/ICSI cycles between January 2015 and December 2019. A defect deeper than 2 mm under three-dimensional (3D) transvaginal sonography (TVS) or visible under hysteroscopy was defined as uterine niche. IVF/ICSI outcomes of the first embryo transfer were obtained by telephone interview 1 year regardless of fresh embryos or frozen-thawed embryos. Generalized estimating equations (GEE), logistic regression analyses, and propensity score matching were applied to clarify the relationship between uterine niche and IVF/ICSI outcomes. Primary outcome was live birth rate. Secondary outcomes were positive human chorionic gonadotropin (hCG) test results, clinical pregnancy rate, implantation rate, miscarriage rate and ectopic pregnancy rate. After excluding 48 cycles for uterine malformation, 18 cycles for chromosome abnormality, 281cycles for no available embryo or no embryo transfer, 5 cycles for oocyte donation and 7 cycles for loss of follow-up, we finally included 2231 women with 2515 cycles in our study. Compared with women without niche, women with niche had reduced live birth rate (18.99% vs. 31.51%, adjusted OR: 0.51, 95% CI: 0.34-0.77), positive hCG test rate (34.08% vs. 46.40%, adjusted OR: 0.61, 95% CI: 0.43-0.87), clinical pregnancy rate (29.05% vs. 42.25%, adjusted OR: 0.57, 95% CI: 0.39-0.82) and implantation rate (25.87% vs. 36.95%, adjusted OR: 0.53, 95% CI: 0.38-0.76). In all the sensitivity analyses, the niche group had an 7.28%-18.22% increase in miscarriage rate even not all of them were statistically significant. Uterine niche may have a detrimental effect on subsequent fertility of women with cesarean section history undergoing IVF/ICSI treatment. Practitioners should be noted that women with uterine niches may associated with adverse IVF/ICSI outcomes.