Relationship Between Dominant Follicle Diameter on the hCG Trigger Day and Live Birth After Modified Natural Cycle Frozen Embryo Transfer: A Retrospective Cohort Study.
4 affiliations
- 1Center for Reproductive Medicine and Obstetrics and Gynecology, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing, 210008, People's Republic of China.
- 2Center for Reproductive Medicine and Obstetrics and Gynecology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China.
- 3Center for Molecular Reproductive Medicine, Nanjing University, Nanjing, 210008, People's Republic of China.
- 4State Key Laboratory of Reproductive Medicine and Offspring Health, Nanjing Medical University, Nanjing, 210008, People's Republic of China.
Abstract
Background
The impact of dominant follicular diameter at hCG trigger on live birth rate (LBR) in modified natural cycle frozen-thawed embryo transfer (mNC-FET) remains unclear. This study aimed to evaluate this relationship and explore whether flexible triggering based on follicle size is acceptable.Methods
A retrospective study included 1669 mNC-FET cycles. The cycles were divided according to the dominant follicle diameter on the hCG day: ≥16 mm (n = 1439) and <16 mm (n = 230). The LBR was compared between the groups, and multivariate logistic regression was performed. A subgroup analysis stratified by maternal age (≥ 35 years) was conducted.Results
Overall, the LBR did not significantly differ between the <16 mm groups (49.0% vs 43.9%, P = 0.152; adjusted OR = 0.878, 95% CI 0.626-1.230). Among advanced-age women (≥35 years), the ≥16 mm group showed a significantly higher LBR (40.2% vs 28.0%, P = 0.048), but multivariate analysis revealed no independent association after adjusting for confounders (aOR = 0.963, 95% CI 0.517-1.791, P = 0.904).Conclusion
Dominant follicular diameter on the hCG day was not independently associated with the live birth rate in mNC-FET. The crude difference seen in women aged advanced-age women (≥35 yeaadjustment and should be viewed as hypothesis-generating rather than effect modification. Flexible triggering may be acceptable, while maternal age remains a key clinical consideration in individualizing trigger timing.
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BibTeX
@article{huang2026relationship,
title = {{Relationship Between Dominant Follicle Diameter on the hCG Trigger Day and Live Birth After Modified Natural Cycle Frozen Embryo Transfer: A Retrospective Cohort Study.}},
author = {Chenyang Huang and Yue Jiang and Jingyu Liu and Yingchun Zhu and Hui Zhang and Ruiwei Jiang and Fangfang He and Jun Xing},
journal = {International journal of general medicine},
year = {2026},
month = oct,
doi = {10.2147/ijgm.s648290},
url = {https://europepmc.org/article/MED/42928808},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Relationship Between Dominant Follicle Diameter on the hCG Trigger Day and Live Birth After Modified Natural Cycle Frozen Embryo Transfer: A Retrospective Cohort Study.
AU - Chenyang Huang
AU - Yue Jiang
AU - Jingyu Liu
AU - Yingchun Zhu
AU - Hui Zhang
AU - Ruiwei Jiang
AU - Fangfang He
AU - Jun Xing
PY - 2026
DA - 2026/10/21
JO - International journal of general medicine
DO - 10.2147/ijgm.s648290
UR - https://europepmc.org/article/MED/42928808
AB - Background The impact of dominant follicular diameter at hCG trigger on live birth rate (LBR) in modified natural cycle frozen-thawed embryo transfer (mNC-FET) remains unclear. This study aimed to evaluate this relationship and explore whether flexible triggering based on follicle size is acceptable.Methods A retrospective study included 1669 mNC-FET cycles. The cycles were divided according to the dominant follicle diameter on the hCG day: ≥16 mm (n = 1439) and <16 mm (n = 230). The LBR was compared between the groups, and multivariate logistic regression was performed. A subgroup analysis stratified by maternal age (≥ 35 years) was conducted.Results Overall, the LBR did not significantly differ between the <16 mm groups (49.0% vs 43.9%, P = 0.152; adjusted OR = 0.878, 95% CI 0.626-1.230). Among advanced-age women (≥35 years), the ≥16 mm group showed a significantly higher LBR (40.2% vs 28.0%, P = 0.048), but multivariate analysis revealed no independent association after adjusting for confounders (aOR = 0.963, 95% CI 0.517-1.791, P = 0.904).Conclusion Dominant follicular diameter on the hCG day was not independently associated with the live birth rate in mNC-FET. The crude difference seen in women aged advanced-age women (≥35 yeaadjustment and should be viewed as hypothesis-generating rather than effect modification. Flexible triggering may be acceptable, while maternal age remains a key clinical consideration in individualizing trigger timing.
SN - 1178-7074
ER -