What's in prenatal vitamins?

What's in prenatal vitamins?

Prenatal vitamins contain a targeted blend of vitamins and minerals designed to meet the elevated nutritional demands of pregnancy. While formulations vary by brand, the core ingredients tend to be consistent across the category. The differences, and they can be significant, come down to the forms used, the doses included, and which nutrients get left out entirely.

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The core ingredients

Folate (400-1350 mcg): The most widely studied prenatal nutrient. Folate supports neural tube formation in the first 28 days after conception and is protective against spina bifida and anencephaly. The form matters here. Methylfolate (L-5-MTHF) is the bioactive form that the body can use directly, which is especially important given that an estimated 40-60% of people carry at least one MTHFR gene variant that can make it harder to convert synthetic folic acid into its active form.

Iron (18-27 mg): Pregnancy roughly doubles your blood volume, and iron is needed to produce the hemoglobin that carries oxygen through that expanded supply. Iron deficiency during pregnancy is linked to anemia, preterm birth, and low birth weight. Iron status before pregnancy also matters, since women entering pregnancy with low stores are more likely to develop deficiency as pregnancy progresses.

Vitamin D3 (600-4000 IU): Supports calcium absorption and fetal bone development. A growing body of evidence suggests that supplementation at higher levels (2000-4000 IU) may reduce the risk of preeclampsia, gestational diabetes, and preterm birth. Many people are low or deficient, especially those with darker skin, limited sun exposure, or who live at higher latitudes.

DHA (200-600 mg): An omega-3 fatty acid that supports fetal brain and eye development, especially during the third trimester when brain growth accelerates. Not all prenatals include DHA in the main formula. In some cases, separating DHA from the prenatal capsule actually preserves its quality by preventing oxidation.

Iodine (150-220 mcg): Supports thyroid function, which regulates metabolism and brain development in the baby. Mild to moderate iodine deficiency is common among women of childbearing age.

Choline (400-450 mg): Supports brain development, neural tube formation, and placental function. Despite strong evidence for its importance, many prenatals still contain little to no choline. A 2022 analysis of 188 prenatal supplements found that choline was one of the most frequently underdosed or missing nutrients.

B vitamins (B1, B2, B3, B5, B6, B7, B12): Support energy metabolism, red blood cell formation, and neurological function. B6 may also help with pregnancy-related nausea. Regular use of a multivitamin containing the spectrum of B vitamins during preconception may decrease the risk of ovulatory infertility.

What's often missing

That same 2022 review of 188 prenatal supplements found significant variability in nutrient content, with many products falling short of evidence-based recommendations for choline, vitamin D, and vitamin K. Only 16% of analyzed prenatals met the researchers' recommendation for vitamin K.

RELATED: 4 key nutrients many prenatals are missing

A note from WeNatal on what's in prenatal vitamins

WeNatal for Her was formulated with these gaps in mind. It includes 1350 mcg of methylfolate, 18 mg of Ferrochel® iron bisglycinate, 4000 IU of vitamin D3, 400 mg of choline, and a full spectrum of B vitamins at clinically relevant doses. All in just three capsules per day. If you've been comparing labels and feeling overwhelmed, start with a prenatal that prioritizes bioavailable forms and evidence-based dosing.

RELATED: The ultimate preconception guide: What to do when you're ready to get pregnant

References

Adams JB, et al. (2022). Evidence based recommendations for an optimal prenatal supplement for women in the US. Maternal Health, Neonatology and Perinatology, 8:4. DOI: 10.1186/s40748-022-00139-9