 These supplements are recommended by the US Surgeon General to help prevent birth complications for mothers and babies such as low birth weight, anemia, hypertension and pre-term birth.Folic acid can aid neural tube formation in a fetus, which happens early in gestation and therefore should be recommended as soon as possible.Calcium and Vitamin A supplements are also recommended when those compounds are not available or only available in low doses in the natural diet but other supplements such as Vitamins D, E, C, and B6 are not recommended.