The number of brain imaging studies related to prenatal drug exposure varies by drug. We were able to identify 20 studies where the drug exposure of interest was alcohol, 10 with cocaine, 5 with tobacco, 4 with marijuana and 2 with methamphetamine. These trends are interesting in that, to some extent they coincide with historical trends in drug use patterns in the U.S. and the availability of imaging techniques. Thus, methamphetamine use by pregnant women is a more recent phenomenon and cocaine use became a societal concern as imaging research was also gaining momentum. However, the fewer number of studies of tobacco and marijuana may indicate less interest in these substances among the scientific community.
