Breastfeeding and postpartum amenorrhea in a traditional society: a hazards model analysis

There is considerable variation in the length of the postpartum amenorrhea during which breastfeeding suppresses fertility, both within and between societies. In this paper, we investigate the association between breastfeeding and the resumption of menses and the impact of various biological and social covariates thereon, using data from two retrospective surveys in India. We use both univariate life table and multivariate time-dependent hazards techniques to analyze the data. Most prior investigations related the impact of breastfeeding to postpartum amenorrhea by taking duration of breastfeeding as a fixed covariate. However, breastfeeding beyond the resumption of menstruation cannot affect the duration of menses. Accordingly, the present study has a methodological focus in the sense that breastfeeding is treated as a time-dependent covariate. We found that breastfeeding, age of mother at child's birth, social status, level of income, religion and caste (subcaste), and residential status have significant effects on return of menses in Indian traditional society.