"During the conflict in Vietnam, married men with dependents could obtain a deferment from the draft. In 1965, following President Johnson’s Executive Order 11241 and a subsequent Selective Service System announcement, the particulars of this policy changed substantially in a way which provided strong incentives for childless American couples to conceive a first-born child. This study examines the effects of the intervention on the decision to start a family. In my empirical analysis, I use data from the Vital Statistics for the period 1963–1968 and employ a difference-in-differences methodology. The estimated magnitude of the effect is substantial."
Interestingly, Dick Cheney's first daughter, Elizabeth, was born 9 months and 2 days after the Selective Service System announced that childless married men were to be drafted.