Five years of fertility control with microdose norgestrel: An updated clinical review.

In 1972 Laurie and Korba reported the results obtained in 8 clinical investigations conducted throughout the U.S. and Puerto Rico in which a daily dose of .075 mg norgestrel (Ovrette) was administered continuously to 2173 sexually active women to prevent conception. 7 of the studies are ongoing and the clinical findings have been updated. Medication has now been continuously administered for 1 to 67 months (average 13 months) to 2202 women for a total of 29006 woman-months. The theoretical pregnancy rate (method failure only) is 1.16 per 100 woman-years and the use-effectiveness pregnancy rate (all pregnancies) is 2.37 per 100 woman-years. Bleeding episodes were found to decrease in length as duration of medication increased with a mean of 5.5 days for the total months of medication. The mean duration of spotting remained and was 3 days for the total months of medication. Only 1.9% of the spotting occurrences lasted longer than 10 days and 73.1% lasted 3 days or less. Clinical side effects with the exception of those related to bleeding patterns were minimal and less than those reported during the pretreatment period. 21.1% of the women discontinued treatment because of common clinical side effects and of these 61.2% withdrew from treatment because of an irregular bleeding pattern or amenorrhea. Weight change was analyzed over 36 months and a mean weight gain of approximately .2 pound per month was reported. Subsequent fertility has not been adversely affected even after long periods of treatment. It is concluded that to date daily continuous administration of .075 mg norgestrel offers an effective method of fertility control with minimal side effects aside from those associated with cycle control and is a useful alternative to oral contraceptives containing estrogen.