The Oxford-Family Planning Association contraceptive study.

The Oxford-Family Planning Association contraceptive study involves over 17 000 women who were recruited at 17 clinics in England and Scotland during the interval 1968-74 and have been followed up ever since. This paper describes the survey methods, the characteristics of the participants, the progress of the study, the main results and publications to date, and the proposals for future work. Although the study was originally mainly concerned with the benefits and risks of oral contraceptives it has, in fact, contributed to knowledge about a wide variety of birth control methods. The data on efficacy are of special value in that they cover all methods of contraception in common use and have been derived from a homogeneous and closely observed population. The mortality figures, while limited in extent, have supplemented the findings in the Royal College of General Practitioners study. Reports on morbidity from many different diseases have been published; these have documented both beneficial and harmful effects of various contraceptive methods. The study data on return of fertility after discontinuation of contraception are unique, while contributions have also been made to knowledge about outcome of pregnancy in those stopping contraception to have a planned baby or becoming accidentally pregnant while using a birth control method. The study, which is supported by the Medical Research Council, is currently funded until mid-1989.