Outcome of pregnancy in women using different methods of contraception.

During the years 1968-74, 17,032 women were recruited to the Oxford Family Planning Association prospective study of the effects of different methods of contraception. The present analysis, which concerns 5700 pregnancies experienced by the participants in the investigation, adds to the evidence that ex-users of oral contraceptives and intrauterine devices suffer no delecterious effects on the outcome of pregnancy in terms of miscarriage, ectopic gestation, stillbirth, congenital malformation, alteration in the sex ratio or reduction in birth weight. Accidental pregnancies in women taking oral contraceptives were few in the present study (66 in all), but it seems likely that harmful effects of exposure of the fetus to the pill in utero, if any, occur infrequently. Women experiencing an accidental pregnancy with an intrauterine device in situ are at a markedly increased risk of miscarriage and ectopic gestation and are more likely to give birth to an underweight infant than other women.