Prenatal vitamins are specific multivitamin and mineral supplements formulated to meet the nutritional demands of pregnancy. Not taking prenatals is associated with specific, well-documented risks, primarily due to the difficulty of obtaining sufficient amounts of certain micronutrients from food alone. The developing fetus relies entirely on the mother’s nutritional status, meaning any shortage can have serious implications for development and health outcomes.
Primary Risks to Fetal Development
The most widely recognized risk of insufficient nutrient intake is the possibility of neural tube defects (NTDs), such as spina bifida and anencephaly. The neural tube, which forms the baby’s brain and spinal cord, closes between the 17th and 30th day after conception, often before a woman realizes she is pregnant. A deficiency of folic acid during this narrow window significantly increases the chances of these abnormalities. Studies suggest that taking folic acid supplements can reduce the risk of NTDs by 50 to 70%.
Adequate intake of other micronutrients is also necessary for healthy fetal development throughout gestation. Insufficient iodine can impair the baby’s thyroid function, which is necessary for proper brain and nervous system development, potentially leading to cognitive defects. Choline and DHA (docosahexaenoic acid) support neurological development and retinal formation; deficiencies are linked to adverse outcomes like preterm birth and lower birth weight.
Consequences for Maternal Health
The fetus draws necessary nutrients from the mother, meaning a lack of supplementation often depletes the mother’s physiological reserves. Iron deficiency is a common consequence, as maternal blood volume increases by up to 50% during pregnancy. Without the 27 milligrams of iron typically found in a prenatal vitamin, the mother faces a high risk of developing iron-deficiency anemia. Anemia can cause fatigue, weakness, and reduced energy levels, and is linked to increased risks of preterm delivery and postpartum depression.
The developing baby requires substantial calcium for bone and teeth formation. If the mother’s diet and supplement intake do not provide enough calcium, the baby extracts it directly from the mother’s bones. This extraction can negatively affect long-term maternal bone density and health.
Evaluating Essential Nutritional Gaps
Relying solely on diet during pregnancy is often insufficient because the required intake levels for certain nutrients increase dramatically. For example, the recommended dose of synthetic folic acid is 400 to 800 micrograms (mcg) per day for those trying to conceive or who are pregnant. It is difficult to consume this quantity through food alone, and the synthetic form found in supplements is absorbed more readily by the body than the naturally occurring folate in foods.
The need for iron also rises, from a typical daily requirement of 18 mg for non-pregnant women to 27 mg during pregnancy. Meeting this increased need through diet can be challenging, especially for women with dietary restrictions or those experiencing food aversions. Studies have shown that up to 90% of pregnant women do not receive adequate nutrients from food alone.
The Importance of Supplementation Timing
The timing of when supplementation begins is particularly important because of the rapid pace of development in the first few weeks of pregnancy. Since the neural tube closes so early in gestation, taking a folic acid supplement should ideally begin at least one month, and preferably three months, before attempting conception. This pre-conception timing ensures adequate levels of the nutrient are available in the mother’s body when the most critical development occurs.
It is beneficial to start taking a prenatal vitamin at any point during pregnancy. While the time-sensitive window for preventing NTDs may have passed, nutrients like iron, calcium, Vitamin D, and DHA remain essential throughout the second and third trimesters. These nutrients continue to support the baby’s rapid growth, oxygen supply, and ongoing bone and brain development until birth.