Defining the "sweet spot" for administered luteinizing hormone-to-follicle-stimulating hormone gonadotropin ratios during ovarian stimulation to protect against a clinically significant late follicular increase in progesterone: an analysis of 10,280 first in vitro fertilization cycles.

OBJECTIVE: To determine whether different ratios of administered LH-to-FSH influence the risk of clinically relevant late follicular P elevations and whether there is an optimal range of LH-to-FSH to mitigate this risk.
DESIGN: Retrospective cohort.
SETTING: Private academic center. PATIENT(S): A total of 10,280 patients undergoing their first IVF cycle. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The ratio of exogenous LH-to-FSH throughout stimulation and association with absolute serum P level≥1.5 ng/mL on the day of hCG administration. RESULT(S): Stimulations using no administered LH (N=718) had the highest risk of P elevation≥1.5 ng/mL (relative risk [RR]=2.0; 95% confidence interval [CI] 1.8-2.2). The lowest risk of P increase occurred with an LH-to-FSH ratio of 0.30:0.60 (20%; N=4,732). In contrast, ratios<0.30, reflecting proportionally less administered LH (N=4,847) were at increased risk for premature P elevation (32%, RR=1.6; 95% CI 1.5-1.7) as were ratios>0.60 (23%, RR 1.1; 95% CI 1.0-1.3). This pattern of lowest risk in the 0.30-0.60 range held true for cycles characterized by low, normal, and high response. When performing a logistic regression to control for multiple confounding variables this relationship persisted. CONCLUSION(S): Absent or inadequate LH dosing is associated with a risk for a late follicular elevation in P sufficient to induce suboptimal outcomes. A total LH-to-FSH ratio of 0.30:0.60 was associated with the lowest risk of P elevation. Optimization of this parameter should be considered when making gonadotropin dosing decisions.