Survey Estimates of the Contraceptive Effect of Breastfeeding in the United States

Martin, Steven P.
Working paper no. 1998-13


This study uses survey data to estimate the overall contraceptive effect of breastfeeding in the United States. In the six months following a first birth, repeat pregnancy rates are low for most U.S. women, but they are lowest for women with a nonteen first birth who are currently breastfeeding. A multivariate analysis shows that only a small part of the association between repeat pregnancy rates and breastfeeding is explained by background characteristics. However, certain circumstances, such as a teen first birth or breastfeeding beyond six months, negate or reverse the contraceptive benefit of breastfeeding. Supplementing or stopping breastfeeding may also increase the risk of a repeat pregnancy but these factors do not produce statistically significant effects in this analysis. In addition, a possible association between breastfeeding and postpartum sexual abstinence might explain away part of the net contraceptive effect of breastfeeding.