What prenatal vitamin should I prescribe?

Prenatal Vitamin Recommendations

For most women planning pregnancy or who are pregnant, a prenatal vitamin containing 400-800 μg (0.4-0.8 mg) of folic acid should be prescribed, with higher doses (4 mg) reserved for high-risk women. 1

Key Components of Prenatal Vitamins

Essential Components:

• Folic acid:

  • 400-800 μg (0.4-0.8 mg) for women at low risk 1
  • 1 mg for women at moderate risk 2
  • 4 mg for women at high risk (previous NTD pregnancy, taking anticonvulsants, etc.) 1, 2

• Iron: 30-60 mg of elemental iron 3

• Vitamin D: At least 400 IU (10 μg) 1

• Calcium: 1200-1500 mg daily (often split between diet and supplements) 1

• Iodine: 150 μg 1

Risk Stratification for Folic Acid Dosing

Low Risk (400-800 μg daily):

• Women with no personal or family history of neural tube defects
• No use of anticonvulsant medications
• No diabetes
• No obesity

Moderate Risk (1 mg daily):

• Women with diabetes
• Obesity (BMI >35)
• Family history of NTDs (not first-degree relative)
• Taking medications that interfere with folate metabolism

High Risk (4 mg daily):

• Previous pregnancy affected by NTD
• Personal history of NTD
• Partner with personal history of NTD
• Taking anticonvulsant medications

Timing of Supplementation

• Begin at least 1 month before conception (ideally 3 months) 1
• Continue through at least 12 weeks of pregnancy for NTD prevention 1
• Continue throughout pregnancy and during breastfeeding 2

Special Considerations

Bariatric Surgery Patients

• Higher doses may be needed: folic acid 800-1000 μg daily 4
• Calcium citrate 1200-1500 mg daily in divided doses 4
• Additional vitamin B12 monitoring and supplementation 4

Diabetes

• Standard prenatal vitamin with folic acid
• Additional focus on glycemic control before and during pregnancy 1
• Eye examinations before pregnancy and during each trimester 1

Cystic Fibrosis

• Standard folic acid dosing (400 μg daily)
• Additional fat-soluble vitamin supplementation may be needed 1

Potential Pitfalls and Caveats

• Vitamin B12 deficiency: Doses of folic acid exceeding 0.4 mg daily may mask B12 deficiency symptoms 5. Ensure prenatal vitamins contain adequate B12 (2.6 μg/day) 2.

• Excessive supplementation: Daily doses of folic acid greater than 1 mg do not enhance hematologic effects, and excess is excreted unchanged in urine 5.

• Timing is critical: Starting supplementation after neural tube closure (28 days post-conception) will not prevent NTDs 1.

• Compliance issues: Approximately 50% of pregnancies in the United States are unplanned, making universal prophylaxis important for all women of reproductive age 1.

• Multivitamin variability: Commercial prenatal supplements vary widely in content and often contain only a subset of essential vitamins, sometimes at suboptimal levels 6.

By prescribing a prenatal vitamin with appropriate folic acid dosage based on risk stratification, you can significantly reduce the risk of neural tube defects and other pregnancy complications, directly improving morbidity, mortality, and quality of life outcomes for both mother and child.