Severe Vitamin B12 Deficiency In An Exclusively Breastfed 5 Month Old Italian Infant Born To A Mother Receiving Multivitamin Supplementation During Pregnancy

This case report describes a serious vitamin B12 deficiency in an exclusively breastfed infant whose vegan mother had taken multivitamin supplements during pregnancy. At 5 months old, the baby was hospitalized with concerning symptoms including poor weight gain, severe paleness, muscle weakness, drowsiness, and delayed development. His growth measurements were all below the 3rd percentile, and he had enlarged liver and spleen. Blood tests revealed dangerously low levels of vitamin B12 (57 pg/mL when normal is 180-500 pg/mL) and severe anemia.

The infant was treated with blood transfusions, vitamin B12 injections, and iron supplements. While his blood levels improved within days and some clinical symptoms resolved within weeks, his developmental delays persisted even seven months after treatment began. Brain imaging showed delayed development of the protective coating around nerve fibers, which likely contributed to the lasting neurological effects.

This case highlights critical gaps in current prenatal care recommendations. Standard multivitamin supplements may not provide adequate vitamin B12 for vegan mothers, who need higher doses both during pregnancy and breastfeeding. The baby's lasting developmental delays underscore how vitamin B12 deficiency can cause permanent neurological damage during critical early brain development periods.

For clinical practice, this case emphasizes the need for healthcare providers to assess dietary patterns more carefully during pregnancy and lactation, ensure appropriate high-dose B12 supplementation for plant-based diets, and monitor infants of vegan mothers for early signs of deficiency to prevent irreversible developmental consequences.