A descriptive observational study of B12 testing during pregnancy and infancy in New Zealand and suggested guidance for testing and treatment.

AIMS: Severe B12 deficiency is harmful to infants. This study describes the recent detection and treatment rates of antenatal and infant B12 deficiency in the Auckland-Northland region.

METHOD: Regional laboratory data on serum B12 levels were analysed. B12 deficient infants and pregnant women were identified and paired with their corresponding mother or infant, followed by a review of electronic health records.

RESULTS

Testing incidence was low in infants (5 per 1,000 infants per year). Among 529 infants tested over 5 years, 6% exhibited B12 deficiency (<148pmol/L). Antenatal B12 deficiency was found in 16% of 6,365 pregnant women tested over 1 year, with high-risk deficiency (<100pmol/L) found in 2%. Both infants and mothers with B12 deficiency had suboptimal rates of adequate treatment. Among infants of high-risk B12 deficient pregnancies, only 1% had serum B12 tested despite being at high risk of infant B12 deficiency.

CONCLUSION

Current guidelines and testing practices in Auckland-Northland inadequately detect and treat B12 deficiency in pregnancy and infancy. A risk-based screening approach is best suited to detect infants at risk of severe deficiency. Antenatal and postnatal recommendations for B12 testing and treatment of mothers and infants are made, along with nutritional advice in pregnancy and infancy.