Because Vitamin B12 is widely available and there is a very low risk of negative reactions to taking large doses of it, there are a lot of claims made about the possible benefits of taking it as a supplement. Some of these claims are based on sound science, some are inferred from debatable scientific data, and some completely lack a scientific basis. The claim that pregnant women should take supplementary Vitamin B12 shots to ensure that there is no deficiency is one of the claims based on solid science and multiple studies and clinical trials. It has been conclusively proven that pregnant women use a lot more Vitamin B12 than they normally do and that a deficiency can result in very serious complications, especially to the developing fetus.

Vitamin B12 has been shown to help women ovulate properly and has been shown to play a direct bearing on the development of the fetus once pregnancy has begun. Several studies conducted in 2008 and 2009 showed that women with low levels of Vitamin B12, with or without a full deficiency, ran a much higher risk of having babies with neural tube defects, such as spina bifida. Further, if there is a full deficiency, there can be very serious consequences to the woman’s health as well. One of these studies was conducted in India, where many women have strict vegetarian diets and are therefore much more prone to Vitamin B12 deficiency since all natural sources of the nutrient come from the consumption of animal products. While this is less of an issue in the western world where vegetarianism is less prevalent, women that maintain a strict vegan diet are particularly at risk.

Some of the studies also indicate that having exceptionally high levels of Vitamin B12 – more than the minimum required to avoid deficiency related problems – appeared to gain additional benefits from it. This is one of the few claims related to Vitamin B12 where the “more is better” mantra is at least partially substantiated by sound medical research. Pregnant women should certainly consider taking a supplementary Vitamin B-12 shot throughout their pregnancies and on through their nursing period. It has also been shown that nursing mothers use a lot more Vitamin B12 than normal.