Pregnancy imposes some physical limits on women but the effects are also very large for men whose crime rates fall by 25-30% during pregnancy of their partner and continue at that lower rate for years afterwards. Keep in mind that in our paper on three strikes, Helland and I found that the prospect of an additional twenty years to life (!) reduce criminal recidivism by just ~17%, so the effect of pregnancy is astoundingly large.
It’s not obvious what the policy implications are. Have children at a younger age doesn’t sound quite right, although in an analysis on teen births Massenkoff and Rose do indeed show that whatever the costs of teen pregnancy there are some offsetting benefits in reduced crime of the parents. More generally, however, there are policy implication if we think beyond the immediate results. First, these results show that crime isn’t simply a product of family background, poverty and neglect. Crime is a choice.