Purpose Smoking during pregnancy may be linked to other problematic prenatal health behaviors in women. We examined interrelationships among prenatal smoking, prenatal health behaviors and mental health. The objective of this study was to examine factors that may contribute to variations in prenatal health practices among women who smoke during pregnancy. Methods Birth mothers from an adoption study (N = 912) were interviewed about prenatal smoking, health behaviors, and mental health symptoms at 5 months postpartum. Results One-quarter of participants (N = 222) reported smoking 6 or more cigarettes daily for at least 1 trimester. For mothers who smoked more than 6 cigarettes daily, higher levels of antisocial behaviors (β = − .14, p = .03) and depressive symptoms (β = − .17, p = .03) were associated with less frequent prenatal folate use; antisocial behaviors and depressive symptoms were not associated for prenatal folate use among women who did not smoke more than 6 cigarettes daily. For mothers who did not smoke more than 6 cigarettes daily, more depressive symptoms were associated with fewer prenatal care visits (β = .12, p = .01). Antisocial behaviors and anxiety symptoms were not associated with prenatal care visits in either group of mothers. Conclusions for Practice Maternal antisocial behaviors and depressive symptoms during pregnancy may be markers for poorer adherence to recommendations for folate supplementation among women who smoke 6 or more cigarettes daily during pregnancy, independent of adequacy of prenatal care.