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Association of maternal folate and vitamin B12 status with birthweight and gestational age at birth in mother-newborn dyads residing in British Columbia Qanaq Adnan , Dalal


Birthweight and gestational age at birth have been inversely associated with chronic disease risk in later life. The vitamins folate and vitamin B12 (B12) have interdependent metabolic functions that are essential for fetal growth. Maternal folate and B12 concentrations during pregnancy have been positively associated with birthweight and gestational age at birth; however, the findings from the literature are inconsistent. The objective of this research was to evaluate the association of maternal serum folate and B12 biomarker concentrations, combined and individually, with birthweight and gestational age at birth. This retrospective cohort study included biobanked non-fasting serum samples and data from 674 apparently healthy pregnant women of South Asian and European ethnicity residing in Lower Mainland, British Columbia (BC). Maternal serum samples, collected in the first and second trimesters of pregnancy, were retrieved from the BC Prenatal Genetic Screening Program and analysed for folate and B12 biomarker concentrations. Birth outcome data were retrieved from the BC Newborn Screening Program. The association of folate and B12 biomarker concentrations with birth outcomes was assessed using multiple linear regression models with adjustment for confounding factors, including infant sex, ethnicity and maternal age. The prevalence of low birthweight, preterm and small-for-gestational-age were 1.9%, 8.9% and 0.88%, respectively. The combined maternal folate and B12 status, in either trimester, was not associated with birthweight or gestational age at birth. Maternal B12 biomarker concentrations individually, in either trimester, were not or only weakly associated with birth outcomes. Second-trimester maternal folate concentrations of the second, third and fourth quartile group (Q2=55.5-69.3, Q3=69.3-87.8, Q4≥87.8 nmol/L, respectively) were associated with an approximate 0.6-week (i.e., 4-day) increase in gestational age at birth, compared to the iii reference group (Q1≤55.5 nmol/L) (95% CI: 0.28, 1.02, p=0.02; 95% CI: 0.23, 0.95, p=0.03, 95% CI: 0.16, 0.89, p=0.005, respectively). In conclusion, early pregnancy folate and B12 status were neither combined nor individually associated with birthweight in this sample. Due to the vitamins’ importance in fetal growth and development, the association between maternal folate and B12 status and birth outcomes warrants further investigation in a population with a higher prevalence of low birthweight and preterm birth.

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