Breastfeeding, contraception, and birth intervals in developing countries.

Numerous studies have demonstrated a strong correlation between breastfeeding and the duration of amenorrhea and between breastfeeding and the birth interval at the individual level. In the present study, both these correlations are shown to hold at the national level, in developing countries. In countries where the median durations of breastfeeding are relatively long or the rates of contraceptive use are relatively high, median birth intervals are longer than in countries where the median breastfeeding durations are shorter and contraceptive use is less widespread. In countries where fertility is moderate or high, however, the incidence of very short birth intervals is higher when median breastfeeding durations are relatively short. The findings suggest that contraception as it is presently practiced is an inadequate substitute for breastfeeding.