Effects of female body mass index on pregnancy during in vitro fertilization-embryo transfer

To investigate the effect of different body mass index (BMI) on transplantation and pregnancy outcomes during assisted reproductive therapy (ART).

This study assessed the data on embryo transplantation from April 1, 2016, to March 31, 2021, at the Hangzhou Women's Hospital. According to the women's BMI, they were divided into three groups: the overweight, normal weight, and overweight groups. The differences in general clinical data, embryo transfer, pregnancy outcome and newborn birth weight were analyzed.

There was no difference in clinical pregnancy rate between the three groups, but a positive correlation between multiple pregnancy rates and BMI in the fresh cycle was observed. Although there was no significant difference in live birth rates among the three groups (p = 0.291), the average birth weight of newborns among the three groups was different (p < 0.05). Furthermore, the mean birth weight of a single fetus was positively correlated with maternal BMI, and the mean birth weight of twins was lower than that of single twins (p < 0.001).

The BMI of women treated with ART did not affect clinical pregnancy outcomes and live birth rates after embryo transfer, but differences in preterm birth rates and newborn birth weight were observed.