Our study attempted to determine the prevalence of regular drinking during the second half of pregnancy among prenatal patients; the characteristics that differentiate drinkers from nondrinkers; and characteristics that differentiate prenatal patients who drink 7 or fewer standard drinks per week and those who drink more than 7. In our survey of consecutive English-speaking prenatal patients over 20 weeks' gestation, women self-reported on health habits from a study questionnaire and completed the General Health Questionnaire and Fetal Health Locus of Control. Eighty-three percent (466 of 561) of women provided data on alcohol intake during the second half of pregnancy: 106 (22.7%) reported regular weekly drinking in pregnancy, and the mean number of standard drinks was 1.97 (SD 9.78, range 0.5-184) per week. Thirty-eight (8.2%) women reported drinking more than seven standard drinks, and 14 (3.0%) reported more than 14 standard drinks per week. Women who drank more than seven standard drinks per week were significantly more likely to be under 21 years of age, poorly educated, unemployed, unmarried, to have unplanned pregnancies, emotional problems, eat unhealthy diets, smoke, use illicit drugs, and be physically abused. They also were more likely to meet psychiatric case status on the General Health Questionnaire (t = 3.85, p = 0.0001) and to believe that "chance" (t = 3.41, p = 0.001) rather than "internal control" (t = -3.54, p = 0.001) affected the health of their fetuses as measured by the Fetal Health Locus of Control. We concluded that pregnant women who drink alcohol often have other health risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)