Women who breastfeed their first child for five months or longer are more likely to have three or more children, and less likely to have only one child, than women who breastfeed for shorter durations or not at all.
In “Intensive Parenting: Fertility and Breastfeeding Duration in the United States,” published in the journal Demography, 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 are as likely to achieve their expectations as to exceed them.
The researchers caution that their results do not imply that breastfeeding duration causes women to have larger families. They write, “Our study reveals the opposite: the interconnectedness of family preferences and child investment across the life course.” But they do find that many factors, such as differences in education, marital status, family income, and working for pay do not explain these patterns. The authors point to the need to study other potential explanations such as spousal support, preferences for time spent with children or work flexibility.