Objective: To investigate the effects of subtle rises in serum progesterone (P) during the follicular phase on the outcome of in vitro fertilization and embryo transfer (IVF-ET).
Design, patients: One hundred one patients underwent IVF-ET for 170 cycles and were stimulated with a combination of clomiphene citrate and human menopausal gonadotropin. Based on their hormonal data, we divided the patients into two groups: those who had a cycle with an increase in serum P concentration (1.0 to 2.0 ng/mL) that was not associated with a pituitary LH release (subtle P rise) and those who had a cycle without any increase in serum P concentration (no P rise).
Main outcome measures: The daily serum estradiol (E2) concentration and the results of IVF-ET (number of developed and collected oocytes, rates of mature oocytes, fertilization, and pregnancy) were compared between the two groups.
Results: Subtle P rises were observed in 31.7% (32/101) of the patients and 20.5% (36/170) of the cycles evaluated during the IVF-ET programs. A significantly higher serum E2 concentration (P less than 0.001) and a greater number of developed and collected oocytes (P less than 0.001 and P less than 0.05, respectively) also were observed in those cycles with a subtle P rise. The rates of mature oocyte formation and fertilization were significantly lower in cycles with a subtle P rise (P less than 0.001 and P less than 0.05, respectively). A lower pregnancy rate was observed in cycles with a subtle P rise, and all 12 ongoing pregnancies occurred only in cycles with a no P rise.
Conclusion: These results suggest that the development of an increased number of follicles may not necessarily improve the outcome of IVF-ET and that the measurement of serum P may be a better predictor for successful pregnancy.