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Published on: December 17, 2017
Small follicle diameter before ovulation may not compromise live birth following the natural frozen embryo transfer
Jie Tong1, Jiali Cai1,2, Yingpei Xu3
1Reproductive Medicine Center, Xiamen University Affiliated Chenggong Hospital, Xiamen, China.
Objective:
Assessing the association between follicle diameter and live birth rates (LBRs) following natural frozen embryo transfer (FET) cycles to justify cycle cancellations.
Methods:
A retrospective study was performed on natural FET cycles. Cycles (n = 7745) were categorized according to their preovulatory follicle size: 3804 in the control group (18-22.9 mm), 894 in group 1 (13.5-15.9 mm), 2546 in group 2 (16-17.9 mm), and 501 in group 3 (23-35.5 mm). A multivariate generalized estimating equation and a generalized additive model were used to evaluate the association between leading follicle size and LBR when follicle size was considered a categorized or continuous variable, respectively. In addition, propensity score (PS) matching analysis was used to evaluate the effect of extreme follicle sizes (<15 mm, n = 410; >25 mm, n = 267).
Results:
The LBRs were 45.8%, 43.6%, 45.8%, and 44.3% in the control group and groups 1-3, respectively. The risk ratios (RRs) in comparison with the control groups in groups 1-3 were 0.95 (95% confidence interval [CI] 0.88-1.03), 1 (95% CI 0.95-1.06), and 0.97 (95% CI 0.87-1.07), respectively. No difference was observed between small extreme (<15 mm) and normal (18-23 mm) leading follicle size groups before and after PS matching. When large extreme (>25 mm) and normal (18-23 mm) leading follicle size groups were compared, the LBRs were 48.3% versus 45.8% (P = 0.462) before and 48.3% versus 49.8% (P = 0.795) after PS matching.
Conclusion:
Intense monitoring in natural FET cycles might be unnecessary, and a more patient-friendly treatment manner could be considered.
