A: Prenatal vitamins can be taken any time during your reproductive years. It's especially important to take folic acid, one of the key components of prenatal vitamins, before you conceive. Many women, therefore, find it easier to begin prenatal vitamins well before conception rather than purchase a separate folic acid supplement. Following pregnancy, a prenatal vitamin is recommended for a nursing mother. Healthy lactation requires many essential vitamins and minerals, and a prenatal vitamin can be an important supplement.