The clinical effectiveness of the rhythm method of contraception
Tietze, C.; Poliakoff, S.R.; Rock, J.
Fertility and Sterility 2(5): 444-450
1951
ISSN/ISBN: 0015-0282 PMID: 14879853 DOI: 10.1016/s0015-0282(16)30664-1Document Number: 475896
At the Free Hospital for Women in Brookline, Mass., a contraceptive clinic prescribing the rhythm method was attended by 551 women during 1936-49. Of these, 409 actual users were observed for an aggregate period of 605.6 yrs. of exposure to the risk of pregnancy. Users observed for a full year or more numbered 185, contributing 84.4% of the total exposure. During the period of clinical observation 57 accidental pregnancies were recorded. A partial follow-up was made of patients who failed to return to the clinic and it is estimated that an additional 30 unplanned pregnancies occurred in this group. The pregnancy rate, based on a total of 87, was 14.4 per 100 yrs. of exposure.