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UBC Theses and Dissertations

Vitamin B-12 status during pregnancy and infancy : screening tools and assessment of populations at risk for deficiency Schroder, Theresa H.


Low perinatal and infantile vitamin B-12 (B-12) status have been associated with health complications. South Asians and residents of low- and middle-income countries may be at increased risk for low B-12 status. The overall goal was to facilitate and screen for perinatal, neonatal, and infantile B-12 status. First, a reliable (recovery: 93–98%; CV: <7%) tool for B-12 status assessment in vulnerable populations was developed, using dried blood spot methylmalonic acid (DBS MMA) concentrations. MMA is the most specific functional B-12 biomarker. Given the minimal invasiveness and ease of DBS collection, DBS MMA may be convenient to use in newborns and populations in remote settings to estimate B-12 status. As such, a reference value of elevated neonatal DBS MMA concentration of >29.3 pmol/8-mm punch was computed per clinical guidelines (CLSI EP18-A3c). Further, B-12 status of South Asian and European pregnant women and their newborns living in Vancouver were compared. B-12 status was assessed in 748 healthy Vancouver women (50% South Asian, 50% European) during their 1st and 2nd trimester of pregnancy using multiple B-12 biomarkers, and in their newborns using DBS MMA concentration. South Asian pregnant women had a significantly lower B-12 status than European women, e.g. comparing 1st trimester mean (95% CI) serum total B-12 concentrations [189 (180; 199) pmol/L versus 246 (236; 257) pmol/L; P<0.0001]. This difference in B-12 status was not reflected in the DBS MMA concentrations of their newborns. Last, the prevalence of B-12 deficiency in mothers and their infants living in rural Indonesia was determined. The prevalence of infants (n=221) living in rural Indonesia with serum total B-12 concentrations <191pmol/L followed at age 6-, 9-, and 12-months was 27%. Maternal DBS MMA concentrations at 6 months postpartum were weakly, but statistically significantly (P=0.004), associated with infant serum MMA concentrations. This research suggests DBS MMA is a convenient screening tool with use in vulnerable populations, including newborns. Pregnant South Asian women living in Vancouver and infants living in rural Indonesia were identified as populations at risk for low B-12 status. Future research evaluating outcomes and predictors of low B-12 status is warranted allowing for targeted interventions.

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