Contraceptive acceptance and pregnancy: a matrix approach to the analysis of competing risks.

Abstract This paper represents an initial attempt to formalize the relationships among post-partum sterility, fecundability, and contraceptive acceptance in terms of absorbing Markov chains. Acceptance of contraception offered by family planning programmes is analyzed as a possible event in time for a cohort of recently delivered women as they pass through phases of temporary sterility and fecundability towards another possible pregnancy. The results of the study indicate that once a woman leaves the post-partum anovulatory stage, the probability of her becoming pregnant again is large compared to the competing rates of contraceptive acceptance currently in force. Unless highly fecund non-contracepting women are approached by family planning programmes shortly after a pregnancy has been terminated (by childbirth or abortion), they will quickly become ineligible to accept either the pill or IUD because of once again being 'currently pregnant'.