Fertility Inhibition by an Injectable Progestogen Acting for 3 Months

Abstract

Norethisterone enanthate in a 200 mg oily solution was given intramuscularly at 3 months intervals for contraceptive purposes to 130 fertile women. The observation period was 2300 months (average per patient 17.6). This dose was effective inhibiting fertility for 4 months. Three pregnancies occurred during the 2nd or 3rd month after the last injection (2.3%). Thirty-three women abandoned therapy due to side effects (25.3%). Fertility was re-established within the 4th to 7th month. Most annoying side effect was the disturbance of menstrual cycles. Oral "accessory" estrogen therapy was used to correct metrorrhagia, spotting, amenorrhea or irregular cycles. Conjugated Estrogens 5.0 to 10.0 mg daily for 5 to 7 days of a calendar month, were effective and well tolerated for this purpose. The long-acting progestogen interferes with fertility by inducing changes in cervical mucus, endometrium and endosalpinx. Evidence of ovulation inhibition Was present in 5 women explored surgically while under therapy. No signs of ovulation or corpus luteum were found. However, follicles development up to Graafian follicle was preserved. In a sixth subject explored 4 months after the last injection, a recent Corpus Luteum was found.