title: 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.
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.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom. C.Bonilla@bristol.ac.uk
authors.forename: Carolina
authors.initials: C
authors.lastname: Bonilla
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
authors.forename: Amy E
authors.initials: AE
authors.lastname: Taylor
authors.forename: David J
authors.initials: DJ
authors.lastname: Gunnell
authors.forename: Yoav
authors.initials: Y
authors.lastname: Ben-Shlomo
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Ness
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Timpson
authors.forename: Beate
authors.initials: B
authors.lastname: St Pourcain
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ring
authors.forename: Pauline M
authors.initials: PM
authors.lastname: Emmett
authors.forename: A David
authors.initials: AD
authors.lastname: Smith
authors.forename: Helga
authors.initials: H
authors.lastname: Refsum
authors.forename: Craig E
authors.initials: CE
authors.lastname: Pennell
authors.forename: Marie-Jo
authors.initials: MJ
authors.lastname: Brion
authors.forename: George Davey
authors.initials: GD
authors.lastname: Smith
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Lewis
mesh_terms: D000328:Adult; D002648:Child; D015986:Confounding Factors, Epidemiologic; D019587:Dietary Supplements; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D056726:Genetic Association Studies; D006239:Haplotypes; D006801:Humans; D007361:Intelligence Tests; D008137:Longitudinal Studies; D008297:Male; D057182:Mendelian Randomization Analysis; D010290:Parents; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011247:Pregnancy; D006113:United Kingdom; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D014805:Vitamin B 12