Vitamin B12 Deficiency Causes Preterm Labor

A study conducted in 11 countries with 11,216 pregnancies has concluded that low levels of vitamin B12 are associated with an increased risk of preterm birth. Diet is an important factor that affects a pregnant woman and her fetus. It is known that low birth weight and preterm births cause 50% of total infant deaths in the first 28 days after birth.

Vitamin B12 is necessary for the body’s vital functions including the production of red blood cells and cellular metabolic energy. B12 deficiency can lead to anemia and cause severe damage to the nervous system. Vitamin B12 cannot be produced by our bodies and has to be consumed through diet.

As B12 is predominantly found in animal products, countries where people eat high levels of animal products, have only a small percentage of pregnant women suffering from B12 deficiency. Whereas, countries where vegetarian diets predominate, such as India, the percentage of pregnant women with B12 deficiency can exceed two-thirds.


“Vitamin B12 is an essential nutrient found only in products of animal origin such as meat, milk, and eggs. Pregnant women who consume too few animal-derived foods increase their risk of developing a vitamin B12 deficiency,” said Tormod Rogne, a medical doctor, and intern at Akershus University Hospital near Oslo. The study is part of his doctoral thesis at the Norwegian University of Science and Technology’s (NTNU) Department of Public Health and Nursing, completed in December 2016.

“Low levels of vitamin B12 in pregnant women did not appear to affect the newborn’s birth weight. But we did find that vitamin B12 deficiency during pregnancy was associated with a 21 percent increased risk of giving birth prematurely,” added Rogne.


Though low levels of Vitamin B12 in pregnant women does not affect the new born’s weight, studies show that B12 deficiency during pregnancy was linked to 21% risk of premature births. The results were independent of whether the countries had high, middle or low average incomes.

“Low blood concentrations of vitamin B12 may be related to other factors, such as malnutrition and poverty, which can also affect birth weight and length of pregnancy. Although we found that vitamin B12 deficiency is associated with an increased risk of preterm birth, we know very little about the effects of taking vitamin B12 supplements during pregnancy,” Rogne said.


Rogne said he knew of only two small studies, for which pregnant women were randomly selected to take either vitamin B12 or a placebo during pregnancy.


These studies found no definitive link between vitamin B12 supplementation and birth weight. This is consistent with the findings from Rogne’s study. However, there were too few participants in the two studies to conclude whether B12 supplementation during pregnancy may reduce the risk of preterm birth.

“Before we can say anything about the effect of vitamin B12 supplementation in pregnancy, more of these kinds of studies need to be done, and the results should then be summarized in a review article. We hope that our article will encourage people to undertake these studies so that we can provide solid advice for pregnant women who don’t eat much in the way of animal-derived foods,” said Rogne.


Vegans don’t eat any foods of animal origin thus making them highly prone to B12 deficiency unless they consume supplements. Vegetarians though, eat dairy products and other foods of animal origin and thereby meet the recommended B12 intake through these foods.

According to a study, a combination of 3 dl milk and 50-75 grams of cheese is the requirement in normal women. In pregnant women, an extra glass of milk or a good portion of yogurt or 3-4 extra slices of cheese will suffice.


B12 is not a big problem for vegetarians given they eat dairy products and eggs. Vegans are advised to consume B12 by drinking products such as soy milk or rice milk with added B12 or to take vitamin supplements. Pregnant women are advised to take vitamin supplements to avoid any premature births or other complications.