Ultrasonographic and endocrine evaluation of ovarian function among Norplant implants users with regular menses

With the objective of evaluating the ovulatory function among long-term Norplant implants users with regular menstrual cycles, we undertook this prospective study including 11 Norplant implants users and 11 control women who were not using hormonal methods of fertility control. Exposed and unexposed women had had at least three regular menstrual cycles preceding enrollment. All women were followed during one menstrual cycle by serial vaginal ultrasound and estradiol (E2), progesterone (P), LH, and FSH measurements. Three Norplant implants users ovulated, three had luteinization of an unruptured follicle (LUF), three had persistent follicle growth up to a mean of 33 mm without rupture, and two had no follicular development beyond 16 mm. Ten of the controls had normal ovulation and one had LUF. Mean peak LH and FSH among Norplant implants users who ovulated were three- to four-fold lower than among controls. Although users of Norplant implants with regular cycles frequently have luteal activity, the results of this study suggest that elevation of P during the second half of the cycle does not necessarily indicate ovulation has occurred and may frequently be associated with the presence of luteinized unruptured follicle. When ovulation occurs, there are usually abnormal hormone levels (low LH/FSH peak, low progesterone) which may also contribute to the contraceptive effect of Norplant implants.