Prevalence of vitamin B-12 insufficiency during pregnancy and its effect on offspring birth weight: a systematic review and meta-analysis

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Prevalence of vitamin B-12 insufficiency during pregnancy and its effect on offspring birth weight: a systematic review and meta-analysis

Sukumar et al., 2016 | Am J Clin Nutr | Meta Analysis

Citation

Sukumar Nithya, Rafnsson Snorri B, ... Saravanan Ponnusamy. Prevalence of vitamin B-12 insufficiency during pregnancy and its effect on offspring birth weight: a systematic review and meta-analysis. Am J Clin Nutr. 2016-May;103(5):1232-51. doi:10.3945/ajcn.115.123083

Abstract

BACKGROUND: Vitamin B-12 and folate are micronutrients essential for normal embryogenesis. Vitamin B-12 insufficiency in pregnancy is high in certain parts of the world, such as India, and although this has been linked to low birth weight (LBW) in these populations, the relation between vitamin B-12 and birth weight (BW) elsewhere is unknown. OBJECTIVES: We performed a systematic review to assess 1) the worldwide prevalence of vitamin B-12 insufficiency in pregnancy and 2) its association with BW. DESIGN: A search of 5 electronic databases was performed to identify eligible articles. Random-effects meta-analysis was conducted according to geographic regions and pregnancy trimesters for the prevalence subreview and by categorical measures of BW. RESULTS: A total of 57 and 23 articles were included for the prevalence and BW subreviews, respectively. The pooled estimates of vitamin B-12 insufficiency were 21%, 19%, and 29% in the first, second, and third trimesters, respectively, with high rates for the Indian subcontinent and the Eastern Mediterranean. The large heterogeneity between studies was partially addressed by creating a standardized score for each study (mean vitamin B-12 insufficiency ÷ cutoff value), which internally corrected for geographic region, trimester, and assay type. Twelve of the 13 longitudinal studies included showed a decrease in mean or median vitamin B-12 across trimesters. Pooled analysis showed nonsignificantly lower maternal vitamin B-12 concentrations in LBW than in normal-BW infants and higher odds of LBW with lower vitamin B-12 values (adjusted OR: 1.70; 95% CI: 1.16, 2.50), but studies from India largely contributed to the latter. CONCLUSIONS: Our review indicates that vitamin B-12 insufficiency during pregnancy is common even in nonvegetarian populations and that concentrations of vitamin B-12 decrease from the first to the third trimester. There is no consistent association between vitamin B-12 insufficiency and LBW. However, given the long-term risks of LBW, this observation warrants further cohort studies and randomized controlled trials.

Key Findings

A total of 57 and 23 articles were included for the prevalence and BW subreviews, respectively. The pooled estimates of vitamin B-12 insufficiency were 21%, 19%, and 29% in the first, second, and third trimesters, respectively, with high rates for the Indian subcontinent and the Eastern Mediterranean. The large heterogeneity between studies was partially addressed by creating a standardized score for each study (mean vitamin B-12 insufficiency ÷ cutoff value), which internally corrected for geog

Outcomes Measured

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Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Birth Weight
  • Databases, Factual
  • Female
  • Folic Acid
  • Humans
  • India
  • Infant
  • Infant, Low Birth Weight
  • Maternal Nutritional Physiological Phenomena
  • Micronutrients
  • Pregnancy
  • Pregnancy Trimester, Third
  • Prevalence
  • Vitamin B 12
  • Vitamin B 12 Deficiency
  • Vitamin B Complex

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Systematic Review
  • Vertical: vitamin-b12

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09