A Long-term follow-up study of women using different methods of contraception— an interim report

Abstract
In 1968, a prospective study was started in collaboration with the Family Planning Association to try to provide a balanced view of the beneficial and harmful effects of different methods of contraception. This investigation is now in progress at seventeen clinics and over 17,000 women are under observation. At the time of recruitment, all these women were married white British subjects, aged 25–39 years, who voluntarily agreed to participate. Fifty-six per cent were using oral contraceptives, 25% were using a diaphragm and 19% were using an intrauterine device (IUD). During follow-up each woman is questioned at return visits to the clinic and a record of pregnancies and their outcome, hospital referrals (inpatient or outpatient), changes in contraceptive methods and the results of cervical smears, is accumulated. Women who default are sent a postal questionnaire and, if this is not returned, are telephoned or visited in their homes to collect the necessary information.