Increased incidence of post-term delivery and Cesarean section after frozen-thawed embryo transfer during a hormone replacement cycle
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This study aimed to clarify the risks of adverse pregnancy outcomes in patients who conceive singletons after frozen embryo transfer (FET) during a hormone replacement cycle and their offspring.
A retrospective cohort study was conducted in patients who conceived after FET, based on the Japanese-assisted reproductive technology registry for 2013. The perinatal outcomes in cases with live-born singletons achieved through natural ovulatory cycle FET (NC-FET) (n = 6287) or hormone replacement cycle FET (HRC-FET) (n = 10,235) were compared. Multiple logistic regression analyses were performed to determine the potential confounding factors.
The frequencies of macrosomia (1.1% in NC-FET and 1.4% in HRC-FET; P = 0.058) were comparable between patients after NC-FET and HRC-FET. The proportions of post-term delivery (0.2% in NC-FET and 1.3% in HRC-FET; P < 0.001) and Cesarean section (33.6% in NC-FET and 43.0% in HRC-FET; P < 0.001) were higher in patients after HRC-FET than in patients after NC-FET. The risks of post-term delivery (adjusted odds ratio (AOR) 5.68, 95% confidence interval (CI) 3.30–9.80) and Cesarean section (AOR 1.64, 95% CI 1.52–1.76) were also higher in patients after HRC-FET than in patients after NC-FET.
Patients who conceived singletons after HRC-FET were at increased risk of post-term delivery and Cesarean section compared with those who conceived after NC-FET.
KeywordsAssisted reproductive technology Hormone replacement cycle Post-term delivery Cesarean section
We would like to thank all of the Japanese fertility clinics for reporting the data and the JSOG for kindly providing the data.
K.S. and H.S. initiated and planned the study. K.S., K.M., K.Y., A.K., E.I., and M.M. analyzed the data. K.S., K.M., A.K., M.F., T.I., T.S., T.K., and H.S. interpreted the results. K.S. and K.M. drafted the manuscript. All of the authors critically reviewed and approved the manuscript.
Compliance with ethical standards
This study was approved by the Institutional Review Board and the registration and research subcommittee of the Japan Society of Obstetrics and Gynecology (JSOG) Ethics Committee.
This study was supported by a Grant from the Japan Agency for Medical Research and Development (No. 15gk0110001h0103). The sponsor had no role in the study design; in the collection, analysis, or interpretation of data; in the writing of the report; or in the decision to submit the article for publication.
Conflict of interest
The authors declare that they have no conflict of interest.
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