Prolactin levels and bromocriptine treatment of short luteal phase.

Moderate hyperprolactinemia was found in 14 of 30 infertile patients with short luteal phase indicating a possible hypothalamic disorder in these patients. While the cycle length was normal, 28 days, late ovulation around day 18 of the cycle was characteristic of these patients. During bromocriptine treatment, 2.5 mg twice daily, ovulation took place earlier and luteal phase became longer irrespective of the basal serum prolactin level. The mean (+/- SEM) duration of luteal phase was 9.9 +/- 0.2 days in control cycles, and 11.7 +/- 0.5 and 12.2 +/- 0.3 days in two successive bromocriptine cycles (P less than 0.001). In patients taking bromocriptine, luteal phase became longer than 11 days in 37 of 60 treatment cycles, but no significant difference was recorded in the circulating progesterone and LH levels during mid- and late luteal phase. Three patients became pregnant and they all had normal baseline serum prolactin concentrations. Our results show that bromocriptine may be effective even when no apparent indication for prolactin suppression can be demonstrated.