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Associations of Maternal Vitamin B12 Concentration in Pregnancy with the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data

Research output: Contribution to journalReview article

Tormod Rogne, Myrte J. Tielemans, Mary Foong Fong Chong, Chittaranjan S. Yajnik, Ghattu V. Krishnaveni, Lucilla Poston, Vincent W. V. Jaddoe, Eric A. P. Steegers, Suyog Joshi, Yap Seng Chong, Keith M. Godfrey, Fabian Yap, Raquel Yahyaoui, Tinku Thomas, Gry Hay, Marije Hogeveen, Ahmet Demir, Ponnusamy Saravanan, Eva Skovlund, Marit P. Martinussen & 4 more Geir W. Jacobsen, Oscar H. Franco, Michael B. Bracken, Kari R. Risnes

Original languageEnglish
Pages (from-to)212-223
Number of pages12
JournalAmerican Journal of Epidemiology
Issue number3
Publication statusPublished - 1 Feb 2017

King's Authors


Vitamin B12 (hereafter referred to as B12) deficiency in pregnancy is prevalent and has been associated with both lower birth weight (birth weight <2,500 g) and preterm birth (length of gestation <37 weeks). Nevertheless, current evidence is contradictory. We performed a systematic review and a meta-analysis of individual participant data to evaluate the associations of maternal serum or plasma B12 concentrations in pregnancy with offspring birth weight and length of gestation. Twenty-two eligible studies were identified (11,993 observations). Eighteen studies were included in the meta-analysis (11,216 observations). No linear association was observed between maternal B12 levels in pregnancy and birth weight, but B12 deficiency (<148 pmol/L) was associated with a higher risk of low birth weight in newborns (adjusted risk ratio = 1.15, 95% confidence interval (CI): 1.01, 1.31). There was a linear association between maternal levels of B12 and preterm birth (per each 1-standarddeviation increase in B12, adjusted risk ratio = 0.89, 95% CI: 0.82, 0.97). Accordingly, B12 deficiency was associated with a higher risk of preterm birth (adjusted risk ratio = 1.21, 95% CI: 0.99, 1.49). This finding supports the need for randomized controlled trials of vitamin B12 supplementation in pregnancy.

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