The significance of elevated early follicular-phase follicle stimulating hormone (FSH) levels: Observations in unstimulated in vitro fertilization cycles

Abstract

Objective: Our objective was to determine the effect of elevated early follicular-phase serum follicle stimulating hormone (FSH) levels on follicle growth and oocyte maturity in unstimulated in vitro fertilization (IVF) cycles.

Study Design: We compared cycles with elevated day 3 FSH levels (>20 mIU/ml) to subsequent cycles in the same patients when day 3 FSH returned to normal and to cycles among women with normal day 3 FSH levels.

Patients: Seven cycles in seven patients had an elevated day 3 FSH (high-FSH group). These were compared to 11 subsequent cycles in which there was a return to a normal baseline FSH and to 13 cycles in 13 patients that entered the unstimulated protocol with a normal baseline day 3 FSH.

Results: The day of human chorionic gonadotropin (hCG) administration was similar in all groups as were the serum estradiol (E₂) levels. Although the high-FSH group tended to have smaller maximum follicular diameters, the difference was not statistically significant. The highest FSH level on cycle day 3 in a completed cycle was 56.2 mIU/ml. The total number of oocytes aspirated and the number of embryos obtained was similar in all groups. Whereas there were no pregnancies in the high-FSH group, 2 of the subsequent 11 normal day 3 FSH cycles resulted in clinical pregnancies. Two of the 13 patients in the normal day 3 FSH values also achieved pregnancies.

Conclusions: We conclude that cycle day 3 serum FSH levels as high as 56.2 mIU/ml may be associated with apparently normal follicular growth, oocyte fertilization, and embryo cleavage in unstimulated cycles. However, pregnancies are not observed. In addition, FSH levels vary widely from cycle to cycle and elevated levels in one cycle do not necessarily imply that pregnancy may not occur in a subsequent cycle when FSH levels return to normal.