IIRC, earlier research by Bledsoe and Davies at UWashington found lots of confounding factors for maternal drug use. For example, alcohol use by crack users dur

IIRC, earlier research by Bledsoe and Davies at UWashington found lots of confounding factors for maternal drug use. For example, alcohol use by crack users during pregnancy was effectively universal making it likely that the crack-baby epidemic in the 90s was most likely FAS. I believe they also found no correlation between marijuana use and developmental delays.