WHO recommendation on vitamin B6 supplementation during pregnancy

WHO recommendation on vitamin B6 supplementation during pregnancy



Vitamin B6 (pyridoxine) supplementation is not recommended for pregnant women to improve maternal and perinatal outcomes.

(Not recommended)


Publication history

First published: November 2016

Updated: No update planned

Assessed as up-to-date: November 2016



  • Pregnant women should be encouraged to receive adequate nutrition, which is best achieved through consumption of a healthy, balanced diet, and to refer to guidelines on healthy eating (1).
  • The GDG agreed that there is insufficient evidence on the benefits and harms, if any, of routine vitamin B6 supplementation in pregnancy. However, research on the effects of routine vitamin B6 supplementation for pregnant women on maternal and perinatal outcomes is not considered a research priority.



Pregnancy requires a healthy diet that includes an adequate intake of energy, protein, vitamins and minerals to meet maternal and fetal needs. However, for many pregnant women, dietary intake of vegetables, meat, dairy products and fruit is often insufficient to meet these needs, particularly in low and middle-income countries (LMICs) where multiple nutritional deficiencies often co-exist. In resource poor countries in sub-Saharan Africa, south-central and south-east Asia, maternal undernutrition is highly prevalent and is recognized as a key determinant of poor perinatal outcomes (2). However, obesity and overweight is also associated with poor pregnancy outcomes and many women in a variety of settings gain excessive weight during pregnancy. While obesity has historically been a condition associated with affluence, there is some evidence to suggest a shift in the burden of overweight and obesity from advantaged to disadvantaged populations (3).

Calcium deficiency is associated with an increased risk of pre-eclampsia (4), and deficiencies of other vitamins and minerals, such as vitamin E, C, B6 and zinc, have also been postulated to play a role in pre-eclampsia. Zinc deficiency is associated with impaired immunity (5). Vitamin C intake enhances iron absorption from the gut; however, zinc, iron and other mineral supplements may compete for absorption, and it is unclear whether such interactions have health consequences (5).



The ANC recommendations are intended to inform the development of relevant health-care policies and clinical protocols. These recommendations were developed in accordance with the methods described in the WHO handbook for guideline development (6). In summary, the process included: identification of priority questions and outcomes, retrieval of evidence, assessment and synthesis of the evidence, formulation of recommendations, and planning for the implementation, dissemination, impact evaluation and updating of the guideline.

The quality of the scientific evidence underpinning the recommendations was graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) (7) and Confidence in the Evidence from Reviews of Qualitative research (GRADE-CERQual) (8) approaches, for quantitative and qualitative evidence, respectively. Up-to-date systematic reviews were used to prepare evidence profiles for priority questions. The DECIDE (Developing and Evaluating Communication Strategies to support Informed Decisions and Practice based on Evidence) (9) framework, an evidence-to-decision tool that includes intervention effects, values, resources, equity, acceptability and feasibility criteria, was used to guide the formulation and approval of recommendations by the Guideline Development Group (GDG) – an international group of experts assembled for the purpose of developing this guideline – at three Technical Consultations between October 2015 and March 2016.

To ensure that each recommendation is correctly understood and applied in practice, the context of all context-specific recommendations is clearly stated within each recommendation, and the contributing experts provided additional remarks where needed.

In accordance with WHO guideline development standards, these recommendations will be reviewed and updated following the identification of new evidence, with major reviews and updates at least every five years.


Further information on procedures for developing this recommendation are available here.


Recommendation question

For this recommendation, we aimed to answer the following question:

  • For pregnant women (P), does Vitamin B6 (pyridoxine) supplementation (I) compared with no intervention or placebo (C) improve maternal and perinatal outcomes (O)?



Evidence summary

The evidence was derived from a Cochrane review that included four trials involving approximately 1646 pregnant women (10). Studies were conducted in HICs between 1960 and 1984. Vitamin B6 (pyridoxine) given intramuscularly as a single dose (100 mg) or orally as capsules or lozenges (2.6 mg to 20 mg per day) was compared with placebo or no treatment. Only two out of four studies contributed data to this comparison.

Maternal outcomes

Low-certainty evidence suggests that oral pyridoxine supplements may have little or no effect on preeclampsia (2 trials, 1197 women; RR: 1.71, 95% CI: 0.85–3.45). No other maternal outcomes relevant to the ANC guideline were reported in the review.

Fetal and neonatal outcomes

Trials contributed no data on low birth weight, preterm birth or other ANC guideline outcomes. Mean birth weight was evaluated in one small trial but the evidence is very uncertain. There was no evidence on congenital anomalies.

Additional considerations

Moderate-certainty evidence shows that vitamin B6 probably provides some relief for nausea during pregnancy (See recommendation: Interventions for common physiological symptoms). Vitamin B6 deficiency alone is uncommon; it mostly occurs in combination with deficiencies of other B vitamins (11).


As a single supplement, vitamin B6 (pyridoxine hydrochloride tablets) can cost about US$ 2.50 for 90 × 10 mg tablets (12).


Effective interventions to improve maternal nutrition in disadvantaged populations could help to address health inequalities.


Qualitative evidence suggests that women in a variety of settings tend to view ANC as a source of knowledge and information and that they generally appreciate any professional advice (including dietary or nutritional) that may lead to a healthy baby and a positive pregnancy experience (high confidence in the evidence) (13).


Qualitative evidence shows that where there are additional costs associated with supplements (high confidence in the evidence) or where the recommended intervention is unavailable because of resource constraints (low confidence in the evidence), women may be less likely to engage with ANC services (14).


Further information and considerations related to this recommendation can be found in the WHO guidelines, available at:



Implementation considerations

  • The successful introduction of evidence-based policies related to antenatal care into national programmes and health care services depends on well-planned and participatory consensus-driven processes of adaptation and implementation. These processes may include the development or revision of national guidelines or protocols based on this recommendation.
  • The recommendation should be adapted into locally-appropriate documents and tools that are able to meet the specific needs of each country and health service. Modifications to the recommendation, where necessary, should be justified in an explicit and transparent manner.
  • An enabling environment should be created for the use of this recommendation, including changes in the behaviour of health care practitioners to enable the use of evidence-based practices.
  • Local professional societies may play important roles in this process and an all-inclusive and participatory process should be encouraged.
  • Antenatal care models with a minimum of eight contacts are recommended to reduce perinatal mortality and improve women’s experience of care. Taking this as a foundation, the GDG reviewed how ANC should be delivered in terms of both the timing and content of each of the ANC contacts, and arrived at a new model – the 2016 WHO ANC model – which replaces the previous four-visit focused ANC (FANC) model. For the purpose of developing this new ANC model, the ANC recommendations were mapped to the eight contacts based on the evidence supporting each recommendation and the optimal timing of delivery of the recommended interventions to achieve maximal impact.


Research implications

The GDG did not identify any priority question related to this recommendation


Related links

WHO recommendations on antenatal care for a positive pregnancy experience

(2016) - full document and evidence tables

Managing Complications in Pregnancy and Childbirth: A guide for midwives and doctors

Pregnancy, Childbirth, Postpartum and Newborn Care: A guide for essential practice

WHO Programmes: Sexual and Reproductive health

WHO Programmes: Department of Nutrition for Health and Development

Maternal Health




  1. Healthy diet. Fact sheet No. 394. Geneva: World Health Organization; 2015 (http://www.who.int/ mediacentre/factsheets/fs394/en/, accessed 1 November 2016).
  2. Tang AM, Chung M, Dong K, Terrin N, Edmonds A, Assefa N et al. Determining a global midupper arm circumference cutoff to assess malnutrition in pregnant women. Washington (DC): FHI 360/Food and Nutrition Technical Assistance III Project (FANTA); 2016 (http:// www.fantaproject.org/sites/default/files/ resources/FANTA-MUAC-cutoffs-pregnantwomen-June2016.pdf, accessed 26 September 2016).
  3. Popkin S, Slining MM. New dynamics in global obesity facing low- and middle-income countries. Obes Rev. 2013;14(2):11–20. doi:10.1111/obr.12102.
  4. Guideline: calcium supplementation in pregnant women. Geneva: World Health Organization; 2013 (http://apps.who.int/iris/ bitstream/10665/85120/1/9789241505376_ eng.pdf, accessed 28 September 2016).
  5. Roohani N, Hurrell R, Kelishadi R, Schulin R. Zinc and its importance for human health: an integrative review. J Res Med Sci. 2013;18(2):144–57.
  6. WHO handbook for guideline development, 2nd edition. Geneva: World Health Organization; 2014 (http://www.who.int/kms/handbook_2nd_ ed.pdf, accessed 6 October 2016).
  7. GRADE [website]. The GRADE Working Group; 2016 (http://gradeworkinggroup.org/, accessed 27 October 2016).
  8. GRADE-CERQual [website]. The GRADECERQual Project Group; 2016 (https://cerqual. org/, accessed 27 October 2016).
  9. The DECIDE Project; 2016 (http://www.decide-collaboration.eu/, accessed 27 October 2016).
  10. Salam RA, Zuberi NF, Bhutta ZA. Pyridoxine (vitamin B6) supplementation during pregnancy or labour for maternal and neonatal outcomes. Cochrane Database Syst Rev. 2015;(6):CD000179.
  11. Allen L, de Benoist B, Dary O, Hurrell R, editors. Guidelines on food fortification with micronutrients. Geneva: World Health Organization and Food and Agriculture Organization of the United Nations; 2006 (http://www.who.int/nutrition/publications/ guide_food_fortification_micronutrients.pdf, accessed 29 September 2016).
  12. Joint Formulary Committee. Vitamin deficiency. Chapter 9: Blood and Nutrition. In: British National Formulary (BNF) 72. London: BMJ Publishing Group Ltd and Royal Pharmaceutical Society; 2016.
  13. Downe S, Finlayson K, Tunçalp Ö, Gülmezoglu AM. Factors that influence the use of routine antenatal services by pregnant women: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2016;(10):CD012392
  14. Downe S, Finlayson K, Tunçalp Ö, Gülmezoglu AM. Factors that influence the provision of good quality routine antenatal care services by health staff: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2016


Citation: WHO Reproductive Health Library. WHO recommendation on vitamin B6 supplementation during pregnancy (November 2016). The WHO Reproductive Health Library; Geneva: World Health Organization.