Birth interval among breast-feeding women not using contraceptives

One hundred twelve Orthodox Jewish mothers were surveyed by means of questionnaire about birth interval in relationship to formula-feeding (n = 30) and breast-feeding (n = 236) experiences in the absence of birth control. Analyses indicate that mothers who breast-fed have longer birth intervals than those who did not. Moreover, data obtained from the same mothers show that birth intervals preceded by breast-feeding were longer than those preceded by formula-feeding of the previous infant. For those mothers who breast-fed, there was significant positive correlation between duration of breast-feeding and the length of lactational amenorrhea and total birth interval. The age at which night feeding was terminated had corresponding but less strong associations with lactational amenorrhea and total birth interval.