The effects of being born with cystic fibrosis on the timing of subsequent births: Evidence from the French Cystic Fibrosis Registry
Cystic fibrosis is an autosomal recessive genetic disease for which there is currently no cure. This study investigated how the birth order of a child with cystic fibrosis influences both the likelihood and timing of subsequent births. We hypothesized that the position of the child with cystic fibrosis within the family birth order is more important than the mere occurrence of the affected birth in determining subsequent fertility behavior. Our results indicate that family characteristics and diversity are strongly shaped by the child’s birth order. First, the birth order position of the child with cystic fibrosis significantly affected the timing of the next birth. Second, accurate estimation of sibling count and age spacing required the inclusion of children with cystic fibrosis whose data were right-censored. Excluding children with cystic fibrosis who were either only children or last-born children led to biased estimates. We conclude that the position of the child with cystic fibrosis within the birth sequence is a key determinant for understanding how the disease influences parental decisions about additional childbearing, as well as how it shapes sibling structure. Our findings have implications for understanding how families change when they face autosomal recessive genetic diseases, because parents must make difficult decisions about whether and when to have another child after the birth of an affected child.
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