Spells, tremors common among infants with vitamin B12 deficiency

Infants with early vitamin B12 deficiency commonly show signs of spells, tremors, and irritability, a new study has found. The administration of nitrous oxide during labour appears to be a risk factor for such deficiency in neonates.

The study included 85 vitamin B12-deficient infants (age <1 year) and a parallel group of 252 control infants (age 3–7 months). The main indication for case referral was spells, observed in 28 patients (33 percent). This was followed by tremors (n=14; 17 percent), irritability (n=12; 13 percent), and hypotonia (n=8; 9.4 percent).

Of note, symptoms presented earlier infants who were exclusively breastfed and whose mothers received nitrous oxide analgesia during labour (mean, 1.17 vs 2.03; p=0.051).

Multiple logistic regression analysis was then performed to assess factors that differentiated cases from controls. Researchers found that infant age, use of B12-containing supplements during pregnancy, exclusive breastfeeding, and self-reported maternal B12 deficiency all independently affected deficiency in infants.

In particular, higher age and use of B12 supplements during pregnancy both significantly suppressed the likelihood of deficiency in infants. On the other hand, exclusively breastmilk feeding and self-reported maternal B12 deficiency aggravated such risk.

Moreover, the dose of analgesic nitrous oxide during labour correlated directly and significantly with infant serum levels of B12 biomarkers total homocysteine (r, 0.372; p<0.001) and methylmalonic acid (r, 0.290; p=0.011). This effect was significant only in B12-deficient infants, not in controls.