The Impact of Multiple Births on Fertility: Stopping and Spacing in the United States During the Demographic Transition.

Multiple births strain mothers' and families' resources in ways that should highlight preferences for family size, birth spacing, and parity-dependent stopping behavior. Couples with surviving twins reach their target family size sooner than other couples and should be more likely to practice family limitation. Twins are also a greater burden on the mother's time and health, which could lead to postponing the next birth, even among couples who want additional children. We examine these hypotheses by analyzing families with twins in the 1900 and 1910 U.S. Censuses. Using reconstructed birth histories for more than 7 million women in the IPUMS full-count 1900 and 1910 datasets and event-history methods (Kaplan-Meier curves, cure models), we find clear evidence of family limitation following a multiple birth. Couples who had twins or triplets were more likely to stop childbearing, and those who continued having children delayed their next birth. Responses to multiple births were larger in groups previously identified as leaders in the transition to smaller families, and roughly one third of couples stopped after one or two children. We find no evidence that some groups relied primarily on birth spacing to reduce family size while others relied primarily on stopping.