Pyridoxine (vitamin B6) supplementation in pregnancy

Thaver D, Saeed MA, Bhutta ZA

Published Online:

January 21, 2009

No evidence that routine supplementation with vitamin B6 during pregnancy is of any benefit and it may cause harm if too much is taken.

B6 is a water-soluble vitamin which helps with the development of the nervous system. B6 is contained in many foods including meat, poultry, fish, vegetables, and bananas. It is thought that B6 may play a role in the prevention of pre-eclampsia and in babies being born too early (preterm birth) but evidence is lacking on this. However, B6 may be helpful for reducing nausea in pregnancy. Overdosing with B6 is reported to be associated with numbness and difficulty in walking. The reviews of trials assessed routine B6 supplementation during pregnancy with the aim of reducing the chances of pre-eclampsia and of preterm birth. However, there were not enough data to be able to make any useful assessments. Further research would be helpful.

Abstract (click to read)

Background:

Vitamin B6 plays vital roles in numerous metabolic processes in the human body, such as nervous system development and functioning. It has been associated with some benefits in non-randomised studies, such as higher Apgar scores, higher birthweights, and reduced incidence of pre-eclampsia and preterm birth. Recent studies also suggest a protection against certain congenital malformations.

Objectives:

To evaluate the clinical effects of vitamin B6 supplementation during pregnancy and/or labour.

Search strategy:

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (30 December 2005).

Selection criteria:

We included randomised controlled trials comparing vitamin B6 administration in pregnancy and/or labour with: placebos, no supplementations, or supplements not containing vitamin B6.

Data collection and analysis:

Two authors independently extracted data and assessed trials for methodological quality. We used relative risk and weighted mean difference with 95% confidence intervals.

Main results:

Five trials (1646 women) were included. Four trials used blinding. One had adequate method of randomisation and allocation concealment; four did not report this. Three trials had large losses to follow up. Vitamin B6 as oral capsules or lozenges resulted in decreased risk of dental decay in pregnant women (capsules: relative risk (RR) 0.84; 95% confidence interval (CI) 0.71 to 0.98; one trial, n = 371; lozenges: RR 0.68; 95% CI 0.56 to 0.83; one trial, n = 342). A small trial showed reduced mean birthweights with vitamin B6 supplementation (weighted mean difference -0.23 kg; 95% CI -0.42 to -0.04; n = 33; one trial). We did not find any statistically significant differences in the risk of eclampsia (capsules: n = 1242; three trials; lozenges: n = 944; one trial), pre-eclampsia (capsules n = 1197; two trials; lozenges: n = 944; one trial) or low Apgar scores at one minute (oral pyridoxine: n = 45; one trial), between supplemented and non-supplemented groups. No differences were found in Apgar scores at one or five minutes, or breastmilk production between controls and women receiving oral (n = 24; one trial) or intramuscular (n = 24; one trial) loading doses of pyridoxine at labour.

Authors' conclusions:

There were few trials, reporting few clinical outcomes and mostly with unclear trial methodology and inadequate follow up. There is not enough evidence to detect clinical benefits of vitamin B6 supplementation in pregnancy and/or labour other than one trial suggesting protection against dental decay. Future trials assessing this and other outcomes such as orofacial clefts, cardiovascular malformations, neurological development, preterm birth, pre-eclampsia and adverse events are required.

This record should be cited as:

Thaver D, Saeed MA, Bhutta ZA. Pyridoxine (vitamin B6) supplementation in pregnancy. Cochrane Database of Systematic Reviews 2006, Issue 2. Art. No.: CD000179. DOI: 10.1002/14651858.CD000179.pub2

Assessed as up to date:

December 30, 2005

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Primary Review Group:

Pregnancy and Childbirth Group

Health topics:

Pregnancy & childbirth > Nutrition during pregnancy and postpartum > Vitamins/minerals

Complementary & alternative medicine > Pregnancy & childbirth > Nutrition during pregnancy and postpartum

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Pyridoxine (vitamin B6) supplementation in pregnancy

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