Analysis of failure time hierarchical data in the presence of competing risks with application to oral contraceptive pill use in Egypt

New Measures for Family Planning and Exposure to Risk of Pregnancy Based on Sexual Activity and Contraceptive Use Data

Family planning measures for unmarried women are based on contraceptive demand and use among sexually active women. Sexual activity status is commonly defined based on comparing reported time-since-last-sex to a cutoff time, with women defined to be sexually active if their most recent sex was within the last four weeks. While easy to understand and compute, this approach to constructing family planning measures results in a limited understanding of family planning and exposure to unintended pregnancy because it cannot comprehensively capture the frequency of sex at the population level. We propose a new statistical approach to quantify sexual activity, using reported time-since-last-sex data. Based on estimated frequencies of sex among users and nonusers in need of family planning, we propose new family planning measures, including the ratio of protected exposure over all women's exposure to risk of unintended pregnancy.

Reproductive Consequences of Contraceptive Failure in 19 Developing Countries

OBJECTIVE

To ascertain the contribution of contraceptive failure to unintended births and fetal loss in developing countries.

METHODS

Nationally representative survey data from married women in 19 developing countries were analyzed. All surveys contained retrospective monthly calendars of contraceptive use and pregnancies for a 5-year period preceding each survey. Information on the intendedness of live births, ascertained earlier in the interview, were linked to the calendar data. Single-decrement life table analysis was applied to episodes of use to estimate failure probabilities. The reproductive consequences of failure were established by simple tabulation. Logistic regression was used to explore the determinants of fetal loss.

RESULTS

Reported contraceptive failure rates were similar to those derived from studies conducted mainly in the United States. About three fourths of pregnancies resulting from contraceptive failure were carried to term, and all but 16% of those were classified by the mother as unwanted or mistimed. Just over one tenth ended in fetal loss, either induced or spontaneous. Analysis of determinants of fetal loss suggested that a large proportion were induced. The median contribution of failure to all unintended births for all 19 surveys was about 15%, and the contribution to fetal loss was 12%.

CONCLUSION

The contribution of contraceptive failure in developing countries is much lower than the estimate of 50% in the United States. Despite the substantial increases in contraceptive practice that have occurred in Asia, Latin America, the Middle East, and to a lesser extent, Africa, the level of use is still below the 75% mark achieved in most industrialized countries. Nonuse of contraception remains the dominant direct cause of unintended births, and family planning promotion should remain a public health priority.