"Recent research stresses the multiple determinants of poor birth outcomes, with important factors including maternal poverty, poor nutrition, homelessness, a history of domestic violence, and lack of prenatal care.3 Because it is difficult to untangle the complex causal relationships between maternal drug use and other contributors to poor birth outcomes,24 it is both simplistic and short-sighted to focus solely on drugs as the source of fetal and childhood harm."
Source
Linda C. Fentiman, Pursuing the Perfect Mother: Why America's Criminalization of Maternal Substance Abuse is Not the Answer- A Compartive Legal Analysis, 15 MICH. J. GENDER & L. 389 (2009).