Risk drinking in pregnancy was defined for this study as an average of one standard North American drink (i.e., 12 oz. beer; 4–5 oz. wine, or 1.5 oz. spirits) per day or an AAD ≥ 0.5 or more than 5 drinks per drinking day (AADD > 2.5) based upon Jacobson, et al., 1993 (see also ACOG, 2006; Jacobson & Jacobson, 1994). At each prenatal visit, the use of cocaine, heroin, marijuana and non-medical opiates were also ascertained by maternal self report and women were classified as users or non-users. Prenatal tobacco exposure was quantified as the typical number of cigarettes the mothers reported they smoked each day.
