Vitamin B12 and Pregnancy


Vitamin B12 deficiency in Pregnant Mothers

Vitamin B12 (cobalamin) is necessary for development of the foetus and neonate. Studies have shown that during pregnancy there is a significant drop in the level of vitamin B12 in the serum of the mothers, which progressively drops further during the course of the pregnancy and while the mothers are breast feeding. Overt vitamin B12 deficiency may occur in pregnant women have lower levels of vitamin B12 at the start of their pregnancy, or who are vegetarian or vegan, have Crohn's or celiac disease, who are on Metformin for diabetes, or have undergone gastric bypass surgery. Low serum levels of vitamin B12 have been linked to negative impacts in cognitive function, and on motor, and growth outcomes in the developing foetus and neonate. Obvious signs of deficiency in the neonate include developmental delay, paleness, apathy, lethargy, anorexia, and failure to thrive. In addition babies of mothers who are deficient in vitamin B12 may have lower cognitive scores one year after birth. After the pregnancy low levels of vitamin B12 in serum may be responsible for depression in the mothers, although studies have not been performed to look at this. Further studies in this area are requited to elucidate the effect of vitamin B12 deficiency  on development, as well as to prevent vitamin B12 deficiency in pregnant women and children.

Absolute vitamin B12 levels are rarely checked in pregnant mothers, rather, levels of iron and macroscopic testing of the blood for obvious signs of deficiency  are performed, and generally folate and iron supplementation is suggested. Childbearing  women are particularly vulnerable to the adverse effects of poor nutrition on mood because pregnancy and lactation are major nutritional stressors to the body. Thus, the developing foetus gains its vitamin B12 (and also other nutrients) from the mother with additional supplementation obtained from the mother's colostrum and milk. As a result, during pregnancy and lactation the nutrient reserves of the mother are particularly stressed, and the lack of recovery postpartum may increase a woman's risk of depression. Several studies have shown that the foetus is able to actively accumulate vitamin B12 with a resultant drop in the mothers serum levels. There is a direct correlation between the vitamin B12 status of the mother and the vitamin B12 status of the new-born. Vitamin B12 levels in colostrum and milk are also directly correlated with those of the mother.  Whilst mothers may not show overt signs of vitamin B12 deficiency (macrocytic anemia), they may give birth to babies who are vitamin B12 deficient. Other signs of vitamin B12 deficiency such as unusual fatigue, nausea, numbness of the fingers and feet are generally ascribed to the "pregnant condition" rather than to vitamin B12 deficiency. Babies born of vitamin B12 deficient mothers will have lower vitamin B12 levels in their liver and serum at birth, and in turn receive lower amounts of vitamin B12 in the milk from their mothers, and as such are at increasing risk of becoming vitamin B12 deficient.

Vitamin B12 deficiency and low birth-weight babies

Deficiency in the mother of either folate or vitamin B12 can lead to increased levels of homocysteine in the blood. A negative association has been found between plasma homocysteine, placental weight and the weight of babies at birth. Low levels of vitamin B12 in mothers has also been associated with intra-uterine growth restriction.

Vitamin B12 deficiency and neural tube defects (NTD)

Vitamin B12 has a vital role in neuronal development, particularly in myelinogenesis. It has been shown that early in vitamin B12 deficiency demyelination of the autonomic nervous system may occur and reduced cardiac sympathetic activity may be observed in children born to mothers with a lower vitamin B12 status. Studies have shown that women with low levels of vitamin B12 (<250ng/L) have two to three times the risk of delivering a child with NTD as compared to those with higher levels. Women with pregnancy blood levels of  <150ng/L had almost five times the risk of having babies with NTD  those with high levels of the vitamin. The neural tube forms very early on in pregnancy so it is very important the a women is tested for vitamin B12 deficiency before becoming pregnant. It is important that pregnant mothers supplement with both folate AND vitamin B12.

Vitamin B12 Supplementation

It is very important that the level of intake of Vitamin B12 is carefully controlled during pregnancy through the use of supplementation which, in the case of vegan mothers or others who are potentially deficient, should be significantly greater than that usually given. Furthermore, supplementation should be continued during lactation in order to avoid the development of signs of deficiency that may be associated with persistent neurological problems in infants. Normal vitamin supplements do NOT provide sufficient vitamin B12 to over-come loss during pregnancy.

Vitamin B12 in Supplements

The use of vitamin B12 in supplements for treatment of deficiency is controversial with many studies showing no benefit being obtained from standard supplements as the amount of vitamin B12 in the standard supplements is too low, Furthermore, studies with high dose oral supplements with cyanocobalamin were not effective in restoring normal levels of homocysteine, in reversing clinical signs of deficiency, or in maintaining normal levels of serum vitamin B12 once supplements were ceased. Furthermore studies have shown that  oral supplements given to VB12 deficient vegan mothers were NOT effective in restoring VB12 levels in new born babies.

Vitamin B12 Injections

Vitamin B12 injections can be administered in cases of insufficiency if it is diagnosed, however they are generally not administered post-partum.

Topical Vitamin B12

A topical form of vitamin B12 has recently been developed which  is easy to administer, contains the natural form of the vitamin and has the added advantage of providing a prolonged release of the vitamin over several days.  This topical formulation is able to provide a much higher dose of vitamin B12 than oral supplements and is ideally suited for pregnant mothers and babies who are deficient.

Further Information on Vitamin B12 supplementation

Further information on vitamin B12 and deficiency states, as well as potential use of vitamin B12 can found by following the links.

For information on topical vitamin B12, contact us.


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Ray JG, Wyatt PR, Thompson MD, et al. Vitamin B12 and the risk of neural tube defects in a folic-acid-fortified population. Epidemiology. 2007 May;18(3):362-6.

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Dror DK, Allen LH. Interventions with vitamins B6, B12 and C in pregnancy. Paediatr Perinat Epidemiol. 2012 Jul;26 Suppl 1:55-74. doi: 10.1111/j.1365-3016.2012.01277.x

Guez S, Chiarelli G, Menni F, Salera S, Principi N, Esposito S Severe vitamin B12 deficiency in an exclusively breastfed 5-month-old Italian infant born to a mother receiving multivitamin supplementation during pregnancy. BMC Pediatr. 2012 Jun 24;12:85

Sucharita S, Dwarkanath P, Thomas T, Srinivasan K, Kurpad AV, Vaz M. Low maternal vitamin B12 status during pregnancy is associated with reduced heart rate variability indices in young children. Matern Child Nutr. 2012 May 24. doi: 10.1111/j.1740-8709.2012.00418.x. [Epub ahead of print]


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