From the Guidelines
Women should ideally start taking prenatal vitamins at least one month before conception, but it's best to begin when planning pregnancy, as recommended by the American College of Medical Genetics 1. If pregnancy is unplanned, start prenatal vitamins as soon as you know you're pregnant. Most prenatal vitamins contain essential nutrients like folic acid (400-800 mcg daily), iron (27 mg), calcium (1,000 mg), vitamin D (600 IU), DHA, and iodine. Folic acid is particularly crucial in the first few weeks of pregnancy—often before a woman knows she's pregnant—as it helps prevent neural tube defects like spina bifida, as supported by the U.S. Preventive Services Task Force recommendation statement 1. Iron supports the increased blood volume needed during pregnancy, while calcium and vitamin D promote proper bone development. When selecting a prenatal vitamin, look for one that contains these key nutrients, and take it daily with food to minimize nausea. Continue taking prenatal vitamins throughout pregnancy and while breastfeeding. If you experience side effects like constipation from the iron content, staying hydrated and increasing fiber intake can help. It's also important to note that women who have had a previous pregnancy affected by neural tube defects or have certain medical conditions may need to take higher doses of folic acid, as advised by the American College of Medical Genetics 1.
From the FDA Drug Label
Folic acid requirements are markedly increased during pregnancy, and deficiency will result in fetal damage Folic acid is usually indicated in the treatment of megaloblastic anemias of pregnancy. The answer is not directly provided in the drug label. The FDA drug label does not answer the question.
From the Research
Prenatal Vitamin Timing
- The ideal time to start taking prenatal vitamins is not explicitly stated in the provided studies, but it can be inferred that taking them before and during pregnancy is recommended for normal fetal development 2.
- Prenatal vitamin use is recommended before and during pregnancies to reduce the risk of pregnancy complications and infant health problems 3.
- It is suggested that increasing prenatal vitamin supplementation to the recommended levels may reduce the incidence of many pregnancy complications and infant health problems 3.
Importance of Prenatal Vitamins
- Prenatal vitamins do not have a standard formulation, but many contain essential nutrients such as calcium, folic acid, iodine, iron, omega-3 fatty acids, zinc, and vitamins A, B6, B12, and D 2.
- Maternal nutrition, particularly micronutrients involved in one-carbon metabolism (folic acid, vitamin B(12), and docosahexaenoic acid (DHA)), have a major role during pregnancy for developing fetus and are important determinants of epigenesis 4.
- Prenatal vitamins may impact epigenetic factors such as DNA methylation, and relationships between maternal prenatal vitamin use and DNA methylation have been relatively understudied 2.
Dietary Intake and Supplementation
- Most pregnant women in the United States are at risk of inadequate intake of vitamin A, vitamin D, folic acid, calcium, iron, and omega-3 fatty acids from foods alone 5.
- Dietary supplements are likely necessary to meet vitamin D and iron targets in pregnancy, as well as omega-3 fatty acid targets for individuals who do not consume fish products 5.
- Increasing prenatal vitamin supplementation to the recommended levels may reduce the incidence of many pregnancy complications and infant health problems 3.