OBJECTIVE: Few studies of maternal prenatal diet and child development examine micronutrient status in relation to fetal assessment. METHODS: Twenty-four-hour dietary recall of zinc and folate and 20min of fetal heart rate were collected from 3rd trimester pregnant adolescents. RESULTS: Deficient zinc was associated with less fetal heart rate variability. Deficient folate had no associations with HRV. Neither deficient zinc nor deficient folate was related to fetal heart rate. CONCLUSIONS: These findings, from naturalistic observation, are consistent with emerging data on prenatal zinc supplementation using a randomized control design. PRACTICAL IMPLICATION: Taken together, the findings suggest that maternal prenatal zinc intake is an important and novel factor for understanding child ANS development.