Premature luteinization: Could it be an early manifestation of low ovarian reserve?

Objective: To gain insight into the physiologic significance of premature luteinization and to evaluate whether it could be a manifestation of low ovarian reserve. Design: Retrospective evaluation. Setting: Reproductive medicine unit. Patient(s): Thirty-one consecutively seen women with normal ovulation and unexplained infertility. Intervention(s): Induction of superovulation with hMG coupled with synchronized IUI. A GnRH agonist was not used during the study. Main Outcome Measure(s): Premature luteinization was defined as a progesterone/estradiol ratio of > 1 on the day of hCG administration. Patients were evaluated during their first cycles of hMG treatment and then were divided into those with (study group) and those without (control group) premature luteinization. The ovarian reserve parameters were compared between the two groups. Result(s): Nineteen of the 31 patients with unexplained infertility demonstrated premature luteinization. Patient characteristics were similar between the study and control groups. Mean (±SD) day 3 FSH levels were 8.2 ± 3.3 and 6.6 ± 1.7 mIU/mL in the study and control groups, respectively. Mean (±SD) day 3 estradiol levels were significantly higher in the study than in the control group (74 ± 49 pg/mL vs. 30 ± 17 pg/mL, respectively). Mean (±SD) estradiol levels on the day of hCG administration also differed significantly between the study and control groups (760 ± 539 pg/mL vs. 1,568 ± 675 pg/mL, respectively). Likewise, the number of follicles that were ≥15 mm on the day of hCG administration was significantly lower in the study than in the control group (2.9 ± 1.5 vs. 4.3 ± 1.3, respectively). The total dose of hMG and duration of administration were similar in the two groups. The clinical pregnancy rates after four cycles of treatment were 15.8% and 41.7% in the study and control groups, respectively. Conclusion(s): This preliminary work suggests that, in cycles that are not treated with a GnRH agonist, signs of premature luteinization in patients with unexplained infertility could be an early manifestation of low ovarian reserve. It appears that hMG treatment in this group of patients could uncover the pathogenesis of their infertility.