Study on the incidence and influences on heterotopic pregnancy from embryo transfer of fresh cycles and frozen-thawed cycles

Shan Xiao, Meilan Mo, Xiaodong Hu, Hongzhan Zhang, Shiru Xu, Zhuran Wang, Yong Zeng

The purpose of this study was to determine the heterotopic pregnancy rate using fresh versus frozen-thawed embryo transfers and factors associated with heterotopic pregnancy (HP). Management and clinical outcomes after heterotopic pregnancy were also evaluated. In this retrospective cohort study, we included 12,484 women who had clinical pregnancies after in vitro fertilization treatment at our fertility center between 2012 and 2017. Patients received fresh day 3 embryos (F-D3 group), fresh day 5 blastocysts (F-D5 group), frozen-thawed day 3 embryos (T-D3 group), or frozen-thawed day 5 or 6 blastocysts (T-D5/6 groups) transfers. The primary outcome measure was the occurrence of heterotopic pregnancy. Factors associated with heterotopic pregnancy were analyzed using logistic regression. The heterotopic pregnancy rates were 0.58% in the F-D3, 0.39% in F-D5, 0.56% in T-D3, and 0.33% in T-D5/6 groups, but no differences were found between groups. The risk factors of HP included a history of previous ectopic pregnancy (odds ratio [OR] 5.805, 95% CI 4.578-9.553, P = 0.016) and pelvic inflammation diseases (OR 1.129, 95% CI 1.021-3.178, P = 0.047). Salpingectomy was performed in 62.9% patients either through laparoscopy or through laparotomy. The early abortion rate and late abortion rate were 29.03% and 1.61%, respectively. In total, 66.13% of the patients had a live birth, either a singleton (90.24%) or twins (9.76%). No significant difference in the incidence of heterotopic pregnancy in fresh IVF cycles vs. frozen-thawed cycles could be demonstrated in a large cohort of patients. The risk factors of HP included history of ectopic pregnancy and PID. The clinical outcome after heterotopic pregnancy appears to be favorable.