Journal of International Reproductive Health/Family Planning ›› 2021, Vol. 40 ›› Issue (6): 446-451.doi: 10.12280/gjszjk.20210292

• Original Article • Previous Articles     Next Articles

Impacts of Female Low Body Mass Index on Pregnancy and Perinatal Outcomes of Frozen-Thawed Embryo Transfer

XIE Qi-jun, LI Xin, JIANG Wei, ZHAO Chun, LING Xiu-feng()   

  1. Reproductive Center, Women′s Hospital of Nanjing Medical University, Nanjing 210004, China
  • Received:2021-07-05 Published:2021-11-15 Online:2021-11-30
  • Contact: LING Xiu-feng E-mail:lingxiufeng_njfy@163.com

Abstract:

Objective: To investigate the impacts of female low body mass index (BMI) on pregnancy and perinatal outcomes of frozen-thawed embryo transfer (FET). Methods: The clinical data of 5 952 women underwent FET in our center from January 2015 to June 2020 were retrospectively analyzed. These cases were divided into two groups according to BMI: group A (BMI<18.5 kg/m2, 697 cases) and group B (BMI=18.5~23.9 kg/m2, 5 255 cases). Then, group A and group B were subgrouped into A1 (1 embryo transferred, 178 cases) and A2 (2 embryos transferred, 519 cases), B1 (1 embryo transferred, 1 275 cases) and B2 (2 embryos transferred, 3 980 cases) according to the transferred embryos. ①The pregnancy outcomes were compared between A1 and A2 subgroup, A1 and B1 subgroup, A2 and B2 subgroup; ②The perinatal outcomes of singleton women were compared between group A and B group. Results: ①The embryo implantation rate (P=0.000), single live birth rate(P=0.000), gestational age (P=0.003) and neonatal birth weight (P=0.000) in subgroup A1 were significantly higher than those in subgroup A2, while the live birth rate of twins(P=0.000), preterm birth rate(P=0.004) and low birth weight rate(P=0.000) in subgroup A1 were significantly lower than those in subgroup A2. The neonatal birth weight in subgroup A1 was significantly lower than that in subgroup B1 (P=0.013). The embryo implantation rate(P=0.000), clinical pregnancy rate (P=0.000), live birth rate(P=0.000), single birth rate(P=0.006) and preterm birth rate (P=0.035) in subgroup A2 were significantly lower than those in subgroup B2. ②After adjusting the confounding factors through multiple logistic regression, the rates of macrosomia and large for gestational age (>90th) in A group was significantly lower than those in B group (aOR=0.493, 95%CI: 0.296-0.821, P=0.007; aOR=0.645, 95%CI=0.473-0.878, P=0.005). Conclusions: In FET cycle, transfering one embryo in the patients with low BMI can significantly reduce the preterm birth rate and multiple pregnancy rate with the advantages of increasing embryo implantation rate and neonatal birth weight and improving pregnancy and perinatal outcomes.

Key words: Body mass index, Frozen-thawed embryo transfer, Embryo transfer, Cryopreservation, Freezing, Pregnancy outcome