Study of norethindrone in contraception
Goldzieher, J.W.; Moses, L.E.; Ellis, L.T.
JAMA 180(5): 359-361
1962
ISSN/ISBN: 1538-3598 PMID: 12305165 DOI: 10.1001/jama.1962.03050180005002Document Number: 475309
The contraceptive effectiveness of 10 mg norethindrone plus .06 mg ethinyl estradiol, administered orally for 20 days of the menstrual cycle, was evaluated in 210 women over 6232 cycles at the Planned Parenthood Center of San Antonio, Texas. There were no unplanned pregnancies during the study period, and not a single patient discontinued use because of side effects. Dysmenorrhea and premenstrual tension diminshed considerably. The incidence of menstrual irregularities, was low. 99 of the women reported an increase in libido. Of 18 patients who discontinued use to become pregnant, 16 became pregnant within the first 3 cycles. The contraceptive effect of norethindrone is thought to be due to the inhibition of ovulation, reinforced by additional protective mechanisms.