Vitamin D Prescription for Infants
All infants should receive 400 IU of vitamin D daily starting at hospital discharge (or soon after birth) and continuing throughout infancy, regardless of feeding method. 1, 2
Standard Dosing by Infant Type
Full-Term Infants (0-12 months)
- Prescribe 400 IU daily of cholecalciferol (vitamin D3) starting at hospital discharge 1, 2
- This applies to both exclusively breastfed and partially breastfed infants 1
- Formula-fed infants consuming ≥28 ounces (approximately 800 mL) of fortified formula daily do not require additional supplementation, as they receive adequate vitamin D from formula 1
- Most formula-fed infants reach 400 IU daily intake from formula alone within the first 2 months of life 3
Preterm Infants
- Prescribe 200-1000 IU daily (or 80-400 IU/kg/day) for preterm infants, with the higher end of this range preferred for very low birth weight infants 1
- For extremely preterm infants (≤28 weeks gestation), doses up to 800 IU/day have been shown safe and effective in correcting deficiency by 2 weeks of age 4
- Continue supplementation throughout the preterm period and transition to standard 400 IU daily dosing once at term-equivalent age 1
Practical Prescribing Details
Formulation Selection
- Cholecalciferol (vitamin D3) is strongly preferred over ergocalciferol (vitamin D2) due to higher bioefficacy 5, 6
- Available as liquid drops (most common), dissolvable tablets, or drops that can be placed on the mother's breast before feeding 3
- Prescribe preparations with 400 IU per dose to minimize dosing errors 3
Alternative Maternal Dosing Strategy
- An alternative to direct infant supplementation is maternal supplementation with 6400 IU daily for breastfeeding mothers, which provides adequate vitamin D through breast milk 1
- This approach may improve compliance in some families but requires maternal adherence 3
Safety Considerations and Upper Limits
Toxicity Prevention
- The tolerable upper limit for infants 0-6 months is 1000 IU/day and for infants 7-12 months is 1500 IU/day 5
- Avoid extremely concentrated preparations (e.g., 5000+ IU per drop) that increase risk of accidental overdosing 3
- Vitamin D toxicity is rare at recommended doses but can cause hypercalcemia at serum 25(OH)D concentrations >375 nmol/L 1, 5
Target Serum Levels
- The goal is to achieve serum 25(OH)D levels >50 nmol/L (20 ng/mL), which indicates sufficiency 1, 5
- Routine serum testing is not recommended for healthy term infants receiving appropriate supplementation 3
- Consider monitoring only in high-risk populations (very preterm infants, those with malabsorption, chronic kidney disease, or liver disease) 1, 3
Common Pitfalls to Avoid
Compliance Issues
- Emphasize starting supplementation at hospital discharge, not waiting until the first outpatient visit, as delays contribute to deficiency 1, 2
- Provide clear written instructions on dosing, as confusion about daily versus weekly dosing can lead to under- or over-supplementation 7
- Address barriers to compliance, particularly in exclusively breastfed infants where supplementation rates are historically lower 7
Dosing Errors
- Do not prescribe 200 IU daily as the sole dose for term infants—research shows 21.3% of infants on 200 IU/day develop deficiency (25[OH]D <30 mcg/L) by 4 months of age, compared to 0% on 400 IU/day 8
- Avoid using active vitamin D analogs (calcitriol, alfacalcidol) to treat nutritional vitamin D deficiency 5
- Double-check that formula-fed infants are not receiving duplicate supplementation if already consuming adequate fortified formula 1, 3
Special Population Considerations
- Infants with dark skin may require higher doses (600 IU/day) due to decreased cutaneous vitamin D synthesis 7
- Infants with chronic kidney disease or liver disease require individualized monitoring and may need adjusted dosing 1, 3
- For infants on parenteral nutrition, ensure vitamin D is included in the formulation and monitor 25(OH)D levels periodically, providing additional supplementation if levels fall below 50 nmol/L 1, 5