Luteinizing hormone dynamics during progestin-primed ovarian stimulation do not predict follicular output in women with normo-ovarian reserve.

BACKGROUND

Progestin-primed ovarian stimulation (PPOS) has emerged as an effective alternative to conventional pituitary suppression strategies in assisted reproductive technology cycles. While suppression of luteinizing hormone (LH) during PPOS is well established, the clinical relevance of dynamic LH changes during stimulation remains unclear. This study aimed to investigate whether serial LH dynamics are associated with follicular output in women with non-low ovarian reserve undergoing PPOS.

METHODS

This retrospective cohort study included 616 ovarian stimulation cycles performed using a PPOS protocol with recombinant follicle-stimulating hormone (rFSH) between January 2019 and January 2025. Serum LH concentrations were measured at three predefined time points: baseline (cycle day 2-3), mid-stimulation (day 6-7), and trigger day. LH dynamics were assessed using calculated changes between time points (ΔLH1, ΔLH2, ΔLH3). Ovarian response was evaluated using the follicle-to-oocyte index (FOI), defined as the ratio of retrieved oocytes to antral follicle count (AFC). Patients were categorized as optimal responders (FOI ≥50%) or suboptimal responders (FOI <50%).

RESULTS

Among the 616 cycles analyzed, 549 patients (89.1%) demonstrated an optimal ovarian response, whereas 67 patients (10.9%) had a suboptimal response. Serum LH concentrations declined during ovarian stimulation in the overall cohort; however, LH levels were comparable between groups at all measured time points. Baseline LH levels were similar between optimal and suboptimal responders (7.21 ± 2.62 vs 7.13 ± 2.79 IU/L, p=0.86), as were mid-stimulation LH levels (6.43 ± 3.54 vs 6.43 ± 4.35 IU/L, p=0.99) and trigger-day LH levels (3.97 ± 2.75 vs 3.92 ± 2.41 IU/L, p=0.88). Dynamic LH changes during stimulation did not differ significantly between groups, including ΔLH1 (-0.77 ± 3.01 vs -0.70 ± 3.50 IU/L, p=0.843), ΔLH2 (-2.47 ± 2.78 vs -2.52 ± 3.13 IU/L, p=0.890), and ΔLH3 (-3.24 ± 2.78 vs -3.21 ± 2.40 IU/L, p=0.936). In multivariable logistic regression analysis, female age (OR 0.909, 95% CI 0.853-0.969, p=0.004) and AFC (OR 0.916, 95% CI 0.892-0.941, p<0.001) were independently associated with ovarian response, whereas LH-related parameters were not significant predictors of follicular output.

CONCLUSION

In women with non-low ovarian reserve undergoing PPOS, serum LH levels decline during stimulation, but their absolute values and dynamic changes are not associated with follicular output.