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Breastfeeding first child for five months or longer increases the chance of having more children. In “Intensive Parenting: Fertility and Breastfeeding Duration in the United States,” Cornell University professor of sociology Vida Maralani, with Hunter College professor Samuel Stabler, reports that women who initiate breastfeeding did not differ in how many children they expected to have before they started their families. Rather, the number of children women actually bear differs by how long they breastfeed their first child.
Women who breastfeed for shorter durations are more likely to have fewer children than they expected, while women who breastfeed longer increase their chance of having more children. This do not imply that breastfeeding duration causes women to have larger families if they decided not to.
The researchers used a nationally representative longitudinal dataset, from 1979 to 2012, which provides information on a cohort of nearly 3,700 mothers. They measured women’s expected fertility at least one year before women conceived their first child to examine the link between their expectations of future fertility and actual behavior. These data also enabled the authors to account for differences in breastfeeding and fertility by education, age, marital status, family income and work histories.
Long-duration breastfeeding serves as a proxy for identifying a group of very highly educated women who seem to achieve and exceed their expected fertility, suggesting that breastfeeding duration may capture numerous observed and unobserved preferences about family and child investment, and necessarily, the tradeoffs that women and couples make.