A longitudinal study of birth control and pregnancy outcome among women in a Swedish population.

The prevalence of contraception and pregnancy outcome in the same women, at 19, 24, and 29 years of age, was assessed in a longitudinal cohort study using a postal questionnaire technique. A one-in-four random sample of all women born in 1962 and resident in the city of Göteborg in 1981, was obtained from the population register (n = 656). Respondents from 1981 were re-assessed in 1986 and 1991. Four hundred thirty women (66%) answered the questionnaire on all three occasions and are included in the analysis. Contraceptive usage was as follows (at 19, 24, and 29 years of age, respectively): oral contraception (OC) 47%/51%/22%; intrauterine device 3%/11%/19%; barrier methods 12%/12%/20%; depot gestagen 0/0.2%/0.4%; no contraception 39%/26%/25%. OCs had been taken at some time by 93%. Reasons give for cessation of OC were: contraception not required 10%/21%/20%; fear of OC 28%/32%/35%; menstrual disorder 17%/13%/14%; weight increase 20%/16%/15%; mental side effects 14%/ 21%/20%; desire to become pregnant 7%/33%/52%. Pregnancy outcome was as follows: Ever pregnant 17%/42%/ 71%; children 5% had 1-2 children/27% had 1-3 children/ 59% had 1-5 children; 12%/25%/30% > or = 1 legal abortion; 3%/8%/15% > or = 1 miscarriage; and > or = 1 ectopic pregnancy 0.2%/1.2%/2.1%. On all three survey occasions, more than 97% of the legal abortions were performed < or = 12 weeks gestation. The complication rate following legal abortion was 7%. The proportion of live births to the total number of pregnancies was 25%, 45%, and 61%. The relationship between method of contraception, history of pregnancy, legal abortion, and smoking habits was analyzed in detail. Despite the availability of effective contraception, the ratio of legal abortions to live births was high. Fear of side effects was the commonest reason for discontinuing OC.