Impact of follicle size before luteal progesterone supplementation on clinical outcomes of modified natural cycle single frozen embryo transfer

Objective

To determine whether follicle size at midcycle transvaginal sonography imaging before luteal progesterone supplementation predicts modified natural cycle single frozen embryo transfer (mNC-SFET) outcomes.

Design

Retrospective chart review.

Subjects

Frozen embryo transfer charts were reviewed. After inclusion and exclusion criteria were applied, data were abstracted from cases of mNC-SFET (n = 115).

Exposure

For group A, lead follicle measuring <16 mm on day of trigger or peak +ovulation predictor kit (n = 50), and for group B, lead follicle measuring ≥16 mm on day of trigger or peak +ovulation predictor kit (n = 65).

Main Outcome Measures

Follicle size analyzed as possible predictor of primary outcome ongoing pregnancy rate (OPR) as well as secondary outcomes implantation rate (IR), clinical pregnancy rate (CPR), and spontaneous abortion (SAB) rate via bivariate associations and multivariate logistic regression analyses.

Results

Bivariate analyses showed no differences between groups in OPR (A, 48.0%, 24/50, and B, 44.6 %, 29/65), IR (A, 64.0%, 32/50, and B, 61.5%, 40/65), CPR (A, 58.0%, 29/50, and B, 52.3%, 34/65), and SAB rates (A, 25.0%, 8/32, and B, 27.5%, 11/40). Multivariate analysis to investigate potential confounding between lead follicle size and outcomes of interest showed no difference in the primary and secondary outcomes. Furthermore, multivariate analyses using lead follicle size as a continuous variable showed no difference in outcomes.

Conclusion

In normo-ovulatory women undergoing mNC-SFET with natural endometrial preparation with human chorionic gonadotropin trigger or luteinizing hormone surge to time frozen embryo transfer, lead follicle size before luteal phase supplementation does not impact clinical outcomes such as IR, CPR, SAB rate, or OPR.