SynthesisAmerican journal of epidemiology2017
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.
Synthesis in American journal of epidemiology, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 103 papers, 10 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
103 citing papers in PubMed, 10 syntheses or guidelines pooled it, 188 citations in OpenAlex.
- Global prevalences of erythropoiesis-associated micronutrient deficiencies (iron, folate, and vitamin BAnnals of medicine · 2025Pooled it
- Micronutrient Deficiencies and Determinants Among Pregnant Women and Children in Nigeria: Systematic Review and Meta-Analysis.Nutrients · 2025Pooled it
- Vitamin B12 supplementation during pregnancy for maternal and child health outcomes.The Cochrane database of systematic reviews · 2024Pooled it
- A sum of its parts: A systematic review evaluating biopsychosocial and behavioral determinants of perinatal depression.PloS one · 2024Pooled it
- A meta-analysis of epigenome-wide association studies on pregnancy vitamin B12 concentrations and offspring DNA methylation.Epigenetics · 2023Pooled it
- A Systematic Review Investigating Maternal Nutrition During Pregnancy After Bariatric Surgery.Obesity surgery · 2023Pooled it
- Investigating the causal effect of maternal vitamin B12 and folate levels on offspring birthweight.International journal of epidemiology · 2021Pooled it
- Maternal Vitamin B12 Status During Pregnancy and Its Association With Outcomes of Pregnancy and Health of the Offspring: A Systematic Review and Implications for Policy in India.Frontiers in endocrinology · 2021Pooled it
- Pooled it
- Maternal Dietary Patterns and Birth Outcomes: A Systematic Review and Meta-Analysis.Advances in nutrition (Bethesda, Md.) · 2019Pooled it
- Trial
- Trial
- Association of antenatal vitamin B complex supplementation with neonatal vitamin BEuropean journal of nutrition · 2021Trial
- Trial
- The association between maternal multivitamin intake and premature birth.Scientific reports · 2026Article
- Maternal Methyl-Group Donor Intake and Neonatal Birth Size in Singleton IVF Pregnancies.Nutrients · 2026Article
- Beyond malaria prevention: sulfadoxine-pyrimethamine treatment in pregnancy selectively remodels the maternal gut microbiome to increase gestational weight gain and improve birthweight.medRxiv : the preprint server for health sciences · 2026Article
- B vitamins and cardiovascular health: mechanisms, clinical evidence, and precision prevention strategies.Nutrition & metabolism · 2026Review
- Micronutrient Deficiency During Pregnancy After Bariatric Surgery: The Role of Micronutrient Supplements and Dietary Intake.Obesity surgery · 2026Article
- Maternal Nutrition During Pregnancy and Fetal Outcome, Short- and Long-Term Health Effects: A Narrative Review.Nutrients · 2026Review
43 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
24 authors.
Funding
Abstract
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-standard-deviation 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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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.