Best Prenatal Vitamins: Evidence-Based Recommendations
All pregnant women should take a daily prenatal multivitamin containing folic acid (400-800 μg), iron (45-60 mg elemental), calcium (1200-1500 mg), vitamin D (≥1000 IU), and other essential micronutrients throughout pregnancy. 1
Core Essential Supplements
Folic Acid (Most Critical)
- Standard dose: 400-800 μg (0.4-0.8 mg) daily starting at least one month before conception and continuing through 12 weeks gestation 2
- High-risk women (BMI >30, diabetes, prior neural tube defect): 4-5 mg daily during periconception period and first trimester, then reduce to 400 μg after 12 weeks 2, 1
- Continue 400 μg throughout remainder of pregnancy to meet fetal growth needs 2
- This is the single most important supplement for preventing neural tube defects with substantial proven benefit 2
Iron
- 45-60 mg elemental iron daily (minimum dose) 2, 1
- Take separately from calcium supplements as calcium inhibits iron absorption 2, 1
- Pair with vitamin C to enhance absorption 2
- Monitor ferritin and iron studies at least once per trimester 2, 1
Calcium
- 1200-1500 mg daily in divided doses (includes dietary intake) 2, 1
- Essential for preventing preeclampsia in populations with low dietary calcium 1
- Must be taken separately from iron for optimal absorption 1
Vitamin D
- ≥1000 IU (40 mcg) daily 2, 1
- Target serum concentration ≥50 nmol/L 2, 1
- Monitor levels with calcium, phosphate, magnesium, and PTH at least once per trimester 2, 1
Additional Essential Micronutrients
B Vitamins
- Thiamine: >12 mg daily 2, 1
- Vitamin B12: 1 mg every 3 months IM or 1 mg oral daily (though oral absorption may be reduced) 2
- Monitor B12 levels at least once per trimester 2, 1
Other Vitamins and Minerals
- Vitamin A: 5000 IU daily in beta-carotene form only (never retinol during pregnancy due to teratogenicity risk) 2, 1
- Vitamin E: 15 mg daily 2, 1
- Vitamin K: 90-120 μg daily 2, 1
- Zinc: 8-15 mg per 1 mg copper 2, 1
- Copper: 2 mg daily 2, 1
- Selenium: 50 μg daily 2, 1
Critical Monitoring Schedule
Every Trimester (Minimum)
- Serum folate or red blood cell folate 2, 1
- Serum vitamin B12 2, 1
- Serum ferritin, iron studies, transferrin saturation, complete blood count 2, 1
- Serum vitamin D with calcium, phosphate, magnesium, PTH 2, 1
- Serum vitamin A 2, 1
Common Pitfalls to Avoid
Vitamin A Toxicity
- Never use retinol form during pregnancy—only beta-carotene form to avoid teratogenic risk 2, 1
- Limit total vitamin A to 5000-10,000 IU daily 2
Supplement Interactions
- Separate calcium and iron by several hours as calcium blocks iron absorption 2, 1
- Take iron with vitamin C to enhance absorption 2
Inadequate Dosing
- Many commercial prenatal vitamins contain suboptimal levels of key nutrients 3
- Verify your prenatal contains at minimum the doses listed above, particularly for folic acid, iron, calcium, and vitamin D 1
Special Population: Post-Bariatric Surgery
- Requires more intensive monitoring every 3 months for folate, B12, ferritin, iron studies, and vitamin A 2
- May need higher doses and alternative routes (IM B12) due to malabsorption 2
- Wait 12-18 months post-surgery before conceiving 1
Practical Algorithm
- Start folic acid 400-800 μg at least 1 month before conception (or 4-5 mg if BMI >30 or diabetic) 2, 1
- Choose a prenatal multivitamin containing all core nutrients at the doses specified above 1
- Take iron separately from calcium (different times of day) 1
- Monitor key nutrient levels each trimester as outlined above 2, 1
- Continue supplementation throughout pregnancy and during breastfeeding 2, 1