Hits and Misses
These studies are from the National Bureau of Economic Research (NBER). They are all gated, but summaries are accessible.
Fasting may have bad health effects. In utero exposure to Ramadan among Arab births in Michigan is associated with lower birthweight, reduced gestation length, and results in fewer male births.
Money for nothing? Medicaid expansions reduce the number of uninsured pregnant women, induce them to drop private insurance, and have no effect on prenatal care use or babies' birth weights.
Drinking causes kids. "…we suspect that lenient drinking laws generate poor birth outcomes because of the increase the number of unplanned pregnancies."
I like that lead: Drinking causes kids.