CONTEXT: Several studies have found a relationship between abortion and prior substance use, suggesting that a reduction in substance use might help decrease abortion rates. However, such a conclusion requires a greater understanding of the processes linking abortion and prior substance use.
CONCLUSIONS: Unconventionality mediates certain associations between substance use and abortion, perhaps because unconventional women are more likely both to use substances and to engage in behaviors that increase their risk of unplanned pregnancy. Hence, it seems unlikely that reducing substance use will result in substantially fewer abortions.