Background: Overweight affects about 34.3% of Chinese adults,
especially women of childbearing age. The purpose of this study was to
investigate whether overweight affect the live birth rate of frozen-thawed embryo
transfer (FET) cycles in Chinese mothers. Methods: This retrospective
case-control study was conducted in all patients undergoing FET cycles from May
2016 to October 2020 at a single center. A total of 969 FET cycles performed in
632 patients were included in the analysis. Patients were divided into the four
groups based on the mother’s body mass index (BMI): Group 1: BMI 18.5
kg/m; Group 2: 18.5 kg/m BMI 24 kg/m; Group 3: 24
kg/m BMI 28 kg/m; Group 4: BMI 28 kg/m. The main outcome indicator was the live birth rate per FET cycle. The
secondary endpoints included rates of biochemical clinical pregnancy, clinical
pregnancy, implantation, multiple pregnancy and miscarriage. Results:
Ovarian reserve parameters were similar among the four groups (p = 0.382
for anti-Müllerian hormone and p = 0.195 for antral follicle count).
Additionally, the rates of chemical pregnancy, clinical pregnancy, implantation
and live birth were comparable in the four groups. Pregnancy outcomes were
similar among the four groups using logistic regression analysis adjusting for
age, anti-Müllerian hormone (AMH), antral follicle count (AFC), endometrial
thickness, indication combined with polycystic ovarian syndrome (PCOS), duration
of infertility (years), stage of embryos transferred, previous attempts, protocol
of endometrial preparation, number of embryos transferred, and BMI. A decreasing
tendency in the rates of clinical pregnancy (p = 0.032) and live birth
(p = 0.011) with BMI change was observed through Chi Square for Trend
test. Conclusions: Overweight might reduce the possibility of live birth
after FET cycles in Chinese mothers.