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. 2012;7(12):e51084.
doi: 10.1371/journal.pone.0051084. Epub 2012 Dec 5.

Vitamin B-12 status during pregnancy and child's IQ at age 8: a Mendelian randomization study in the Avon longitudinal study of parents and children

Carolina Bonilla  1 , Debbie A Lawlor, Amy E Taylor, David J Gunnell, Yoav Ben-Shlomo, Andrew R Ness, Nicholas J Timpson, Beate St Pourcain, Susan M Ring, Pauline M Emmett, A David Smith, Helga Refsum, Craig E Pennell, Marie-Jo Brion, George Davey Smith, Sarah J Lewis
Affiliations

Vitamin B-12 status during pregnancy and child's IQ at age 8: a Mendelian randomization study in the Avon longitudinal study of parents and children

Carolina Bonilla et al. PLoS One. 2012.

Abstract

Vitamin B-12 is essential for the development and maintenance of a healthy nervous system. Brain development occurs primarily in utero and early infancy, but the role of maternal vitamin B-12 status during pregnancy on offspring cognitive function is unclear. In this study we assessed the effect of vitamin B-12 status in well-nourished pregnant women on the cognitive ability of their offspring in a UK birth cohort (ALSPAC). We then examined the association of SNPs in maternal genes FUT2 (rs492602) and TCN2 (rs1801198, rs9606756) that are related to plasma vitamin B-12, with offspring IQ. Observationally, there was a positive association between maternal vitamin B-12 intake and child's IQ that was markedly attenuated after adjustment for potential confounders (mean difference in offspring IQ score per doubling of maternal B-12 intake, before adjustment: 2.0 (95% CI 1.3, 2.8); after adjustment: 0.7 (95% CI -0.04, 1.4)). Maternal FUT2 was weakly associated with offspring IQ: mean difference in IQ per allele was 0.9 (95% CI 0.1, 1.6). The expected effect of maternal vitamin B-12 on offspring IQ, given the relationships between SNPs and vitamin B-12, and SNPs and IQ was consistent with the observational result. Our findings suggest that maternal vitamin B-12 may not have an important effect on offspring cognitive ability. However, further examination of this issue is warranted.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Diagram showing the framework of the Mendelian randomization approach used in this study.
Figure 2
Figure 2. Flow-diagram of participants in the study, and reasons for exclusions.
See this image and copyright information in PMC

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