The Effect of Vitamin B-12 Supplementation During Pregnancy on Early Motor Performance: Secondary Analyses From a Double-Blinded Randomized Controlled Trial.

Maternal vitamin B-12 supplementation during pregnancy had a negative effect on infant motor performance that was observed across most subgroups.

• Secondary analyses of a double-blind RCT in Nepal with 800 pregnant women randomly assigned to vitamin B-12 or placebo from early pregnancy to 6 months postpartum.
• Motor development was measured by the Test of Infant Motor Performance (TIMP) in 712 infants at age 8 to 12 weeks.
• The negative effect of vitamin B-12 supplementation was observed in most subgroups examined.
• Subgrouping variables were categorized according to predefined cutoffs and included as interaction terms in generalized linear models.

Plasma folate concentration significantly modified the effect of vitamin B-12 supplementation on infant TIMP scores.

• The P-interaction for plasma folate concentration was 0.015, making it the only baseline maternal characteristic that significantly modified the effect.
• There was a tendency for a stronger negative effect of vitamin B-12 among infants of women with folate concentration in the lower tertile.
• No other maternal baseline characteristics significantly modified the effect of vitamin B-12 supplementation on TIMP scores.

The negative effect of vitamin B-12 supplementation on infant motor performance appeared more pronounced in mothers with adequate baseline vitamin B-12 status.

• Adequate vitamin B-12 status was defined as cobalamin >220, tHcy <10, MMA <0.26, and cB12 values >-0.5.
• There was a tendency for a stronger negative effect of vitamin B-12 among infants of women with adequate baseline vitamin B-12 status across all four markers examined.
• Baseline maternal characteristics examined included cobalamin, total homocysteine (tHcy), methylmalonic acid (MMA), cB12, folate, hemoglobin concentration, and socioeconomic status (SES).

Maternal baseline vitamin B-12 status markers, hemoglobin concentration, and socioeconomic status did not significantly modify the effect of vitamin B-12 supplementation on infant TIMP scores.

• Subgrouping variables included plasma markers of baseline maternal vitamin B-12 status: cobalamin, tHcy, MMA, and cB12.
• Hemoglobin concentration and socioeconomic status were also examined as potential effect modifiers.
• None of these variables produced statistically significant interaction terms in the generalized linear models.
• Both continuous and categorical TIMP scores were used as outcomes.

The trial was conducted in Nepal with 800 pregnant women receiving vitamin B-12 or placebo from early pregnancy through 6 months postpartum.

• The trial was registered at clinicaltrials.gov as NCT03071666.
• 712 infants were assessed for motor development at age 8 to 12 weeks.
• The study used a double-blind randomized controlled trial design.
• These reported findings are secondary analyses of the primary RCT.