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

OBJECTIVE

To investigate the relationship between uterine niche and reproductive outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).

DESIGN

A retrospective cohort study.

SETTING

A reproductive medicine center.

PATIENT(S): A total of 2,449 women with cesarean section history who underwent 2,874 IVF/ICSI cycles between January 2015 and December 2019.

INTERVENTION(S): A defect deeper than 2 mm visible under three-dimensional transvaginal sonography or hysteroscopy was defined as uterine niche. The IVF/ICSI outcomes of the first embryo transfer were obtained by telephone interview 1 year after embryo transfer regardless of fresh embryos or frozen-thawed embryos. Generalized estimating equations, logistic regression analyses, and propensity score matching were applied to clarify the relationship between uterine niche and IVF/ICSI outcomes.

MAIN OUTCOME MEASURE(S): Primary outcome was live birth rate. Secondary outcomes were positive human chorionic gonadotropin test results, clinical pregnancy rate, implantation rate, miscarriage rate, and ectopic pregnancy rate.

RESULTS

After excluding 48 cycles for uterine malformation; 18 cycles for chromosome abnormality; 281 cycles for no available embryo or no embryo transfer; 5 cycles for oocyte donation; and 7 cycles for loss of follow-up, we finally included 2,231 women with 2,515 cycles in our study. Compared with women without niche, women with niche had reduced live birth rate (18.99% vs. 31.51%, : 0.51, 95% CI: 0.34-0.77), positive human chorionic gonadotropin test rate (34.08% vs. 46.40%, adjusted odds ratio [aOR]: 0.61, 95% confidence interval [CI]: 0.43-0.87), clinical pregnancy rate (29.05% vs. 42.25%, aOR: 0.57, 95% CI: 0.39-0.82) and implantation rate (25.87% vs. 36.95%, aOR: 0.53, 95% CI: 0.38-0.76). In all the sensitivity analyses, the niche group had a 7.28% to 18.22% increase in miscarriage rate even not all of them were statistically significant.

CONCLUSION(S): 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 be associated with adverse IVF/ICSI outcomes.