Objective: To determine the risk of pregnancy during lactational amenorrhea relative to infant feeding status.
Design: Prospective longitudinal study.
Setting: Five developing and two developed countries.
Patient(s): Four thousand one hundred eighteen breast-feeding mother-infant pairs.
Intervention(s): Infant feeding practices, menstrual status, and pregnancy were measured.
Main outcome measure(s): Life-table rates of pregnancy.
Result(s): In the first 6 months after childbirth, cumulative pregnancy rates during amenorrhea, depending on how the end of amenorrhea was defined, ranged from 0.9% (95% confidence interval [CI] = 0%-2%) to 1.2% (95% CI = 0%-2.4%) during full breast-feeding, and from 0.7% (95% CI = 0.1%-1.3%) to 0.8% (95% CI = 0.2%-1.4%) up to the end of partial breast-feeding. At 12 months, the rates ranged from 6.6% (95% CI = 1.9%-11.2%) to 7.4% (95% CI = 2.5%-12.3%) during full breast-feeding, and from 3.7% (95% CI = 1.9%-5.5%) to 5.2% (95% CI = 3.1%-7.4%) up to the end of partial breast-feeding.
Conclusion(s): These results support the Bellagio Consensus on the use of lactational amenorrhea for family planning, and confirm that the lactational amenorrhea method is a viable approach to postpartum contraception.