If you’re planning on taking vitamin B6 to ease morning sickness, you will want to ensure your baby is safe and you are not taking any unnecessary risks with your pregnancy.
Is Vitamin B6 Safe in Pregnancy?
Very large doses of vitamin B6 have been known to cause pyridoxine neuropathy, a condition characterized by numbness and tingling of the arms and legs. If the same high levels of vitamin B6 continue to be taken, this condition can progress. Anyone experiencing these symptoms should stop taking vitamin B6 as pyridoxine neuropathy reverses once B6 is stopped.
Pyridoxine neuropathy does not usually occur in dosages less than 1,000mgs a day but sometimes it can occur in dosages as low as 50mgs. However, it is very unlikely to occur if you take a dose of 100mgs or less. It has been found to be generally safe in pregnancy at these levels.
Will Vitamin B6 Cause Birth Defects?
A study at University of Toronto, Canada, found that taking large doses of vitamin B6 did not increase the risk of birth defects.
‘Vitamin B6 is often prescribed for the treatment of nausea and vomiting of pregnancy (NVP), at much higher doses than initially recommended. Large doses of vitamin B6 have been associated with cases of neuropathy. We set out to assess whether higher than standard doses of vitamin B6 during the first trimester of pregnancy were associated with a risk of maternal adverse events, major malformations, miscarriages or low birth weight. A total of 192 pregnancies were followed-up. The mean dose of B6 used in the study group was 132.3 mg/day (median 110 mg/day, range 50 - 510 mg/day), for a mean period of 9 +/- 4.2 weeks. In this group (n = 96), there were 91 live births, one major malformation and the mean birth weight was 3,542 +/- 512 g. There were no statistical differences in the study endpoints between the vitamin B6 and the control groups. Within the limits of our sample size, higher than standard doses of vitamin B6 do not appear to be associated with an increased risk for major malformations..’
There was some controversy about an anti-sickness drug containing vitamin B6, causing birth defects, but this was a pharmaceutical drug with added B6, and not just the vitamin.
Does Vitamin B6 actually work at preventing morning sickness?
A review of the literature, a study compared pregnant women taking an anti-sickness drug with those taking vitamin B6 and found that:
‘Anti-emetic medication appears to reduce the frequency of nausea in early pregnancy. There is some evidence of adverse effects, but there is very little information on effects on fetal outcomes from randomised controlled trials. Of newer treatments, pyridoxine (vitamin B6) appears to be more effective in reducing the severity of nausea.’
Another study in Canada found that women who were treated with a drug containing vitamin B6, had a significantly decreased risk that severe morning sickness would occur.
A study in Thailand involving 342 women found that 30mgs of vitamin B6 per day was effective at preventing morning sickness.
‘During an 11-month period 342 women who first attended Chiang Mai University Hospital antenatal clinic at less than 17 weeks' gestation were randomized to receive either oral pyridoxine hydrochloride, 30 mg per day, or placebo in a double-blind fashion. Patients graded the severity of their nausea by a visual analog scale and recorded the number of vomiting episodes over the previous 24 hours before treatment and again during 5 consecutive days on treatment. Pyridoxine is effective in relieving the severity of nausea in early pregnancy.’
A study in Iowa, USA, found that vitamin B6 was better at reducing morning sickness than a placebo. Eight of 31 patients had nausea after treatment with vitamin B6, compared with 15 out of 28 patients in the placebo group.
Vitamin B6 may be particularly important for pregnant women who are taking antibiotics, as these disrupt the natural flora of the gut and result in lowered vitamin B6.
If you want to take the supplement, dosages of 100mgs or less normally do not cause problems. Doctors commonly prescribe 75mgs daily in timed release tablets, or you could take three 25mgs tablets at different times in the day. If you’re unsure, speak to your healthcare provider.
Sources: Cochrane Database Syst Rev. 2003;(4):CD000145.
Can Fam Physician. 2006 Dec;52(12):1545-6.
Am J Obstet Gynecol. 1995 Sep;173(3 Pt 1):881-4
Obstet Gynecol. 1991 Jul;78(1):33-6
J Obstet Gynaecol. 2006 Nov;26(8):749-51
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting, in addition to running a charity for people damaged by vaccines or medical mistakes.