Live birth rate of twin pregnancies after frozen embryo transfer: natural cycle versus ovulation induction regimens

• Published in: Archives of gynecology and obstetrics Vol. 304; no. 3; pp. 619 - 626
• Main Authors: Zhao, Depeng, Zhao, Guanglin, Fan, Jing, Chen, Haiyan, Lopriore, Enrico, Li, Xuemei
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2021; Springer Nature B.V
• Subjects: Birth rate; Endocrinology; Endometrium; Gynecology; Human Genetics; Maternal-Fetal Medicine; Medicine; Medicine & Public Health; Obstetrics/Perinatology/Midwifery; Ovulation; Pregnancy; Regression analysis; Frozen embryo transfer; Twin pregnancies; Endometrium preparation
• ISSN: 0932-0067; 1432-0711
• DOI: 10.1007/s00404-021-06014-w

Purpose
Ovulation induction (OI) using letrozole or human menopausal hormone (hMG) is recently developed for endometrium preparation in frozen embryo transfer (FET) cycles. The purpose of this study is to compare the live birth rate of twin pregnancies between modified natural and OI regimens for endometrium preparation in FET cycles.
Study design
This study included all consecutive twin pregnancies following FET with modified natural cycle (mNC-FET) or OI (OI-FET) regimen for endometrium preparation between January 2015 to June 2019. Primary outcome was the live birth of at least one twin per pregnancy. Multivariable logistic regression analysis was used to evaluate the potential association of endometrium preparation regimen and live birth. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.
Results
During the study period, 269 twin pregnancies after mNC-FET and 177 twin pregnancies after OI-FET were included. The live birth rate of at least one twin per pregnancy was not significantly different between mNC-FET and OI-FET groups, 92.2% vs 90.4%; aOR 0.65; 95%CI 0.32–1.34. The multivariable regression analysis showed that twin pregnancies after OI-FET had decreased odds for gestational diabetes mellitus (aOR 0.37; 95% CI 0.16–0.87) in comparison to twin pregnancies after mNC-FET. In subgroup analysis, we found that the rate of live birth of at least one twin per pregnancy was significantly higher in OI-FET cycles using letrozole compared to those using hMG (94% vs 83.3%; aOR 3.45; 95%CI 1.24–9.57).
Conclusion
The live birth rate in twin pregnancies after FET is comparable between mNC or OI regimens for endometrium preparation.