OBJECTIVE: Interest in herbal treatments has increased without data on safety, efficacy, or rates of use in pregnancy. We examined antenatal herbal and natural product use among mothers of nonmalformed infants in 5 geographic centers.

STUDY DESIGN: We used data on nonmalformed infants from the Slone Epidemiology Center's case-control surveillance program for birth defects to examine rates and predictors of herbal use. Exposures were identified through maternal interview. In addition to overall use, 5 categories based on traditional uses and 2 natural product categories were created; topical products and herbal-containing multivitamins were excluded.

RESULTS: Among 4866 mothers of nonmalformed infants, 282 (5.8%) reported use of herbal or natural treatments. Use varied by study center and increased with increasing age.

CONCLUSION: Although rates of use are low, there remains a need for investigation of the safety of these products. Given sparse data on efficacy, even small risks might well outweigh benefits.