Pregnant women who adhere to a vegetarian or vegan diet may be at increased risk for preterm birth. The possible culprit? Low levels of vitamin B12.
Researchers from the Norwegian University of Science and Technology (NTNU) took an in-depth look at more than 11,000 pregnancies in 11 countries where levels of B12 had been tracked, and they discovered a “linear association” between suppressed levels of the vitamin and preterm birth.
Ultimately, they found that vitamin B12 deficiency led to a 21 percent increased risk of giving birth prematurely.
Because vitamin B12 is found exclusively in animal protein, women who avoid meat and animal products altogether or who eat fewer animal products appear to be at increased risk of preterm birth. Vitamin B12 is found naturally in meat, eggs, milk and animal organs, such as liver.
“Pregnant women who consume too few animal-derived foods increase their risk of developing a vitamin B12 deficiency,” said lead author Tormod Rogne, a medical doctor and intern at Akershus University Hospital near Oslo, Norway.
“In countries where vegetarian diets predominate, such as in India, the percentage of pregnant women with B12 deficiency can exceed two thirds,” Rogne said.
About 10 percent of babies are born before 37 weeks of pregnancy, which is considered preterm, and early birth can result in various challenges, including breathing problems, cerebral palsy and vision and hearing impairments.
Scientists Call for More Research
The researchers caution that, while their results offer a potential route to healthier pregnancies, more studies are necessary to tease out other factors that may come into play during a woman’s pregnancy.
“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,” noted Rogne.
The same wait-and-see approach is advisable for B12 supplementation, the researchers say.
“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,” asserted Rogne.
“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,” he added.
Ways to Boost B12 Levels
In the meantime, women can take steps to boost their vitamin B12 levels through supplemental means. To that end, it’s vital to distinguish between vegans and vegetarians when evaluating diet, said Vibeke Videm, a professor in NTNU’s Department of Laboratory Medicine, Children and Women’s Health.
Because vegans don’t eat animal products, they will become B12-deficient without supplements, noted Videm. Most vegetarians who consume dairy products and eggs meet recommended levels of B12, she added.
Many foods, including milk and grains, are fortified with vitamin B12, which can help reduce the chance of health challenges. Most vegans do not consume enough B12 to avoid pregnancy complications, notes the Vegan Society, which recommends fortified food.
The study was published in the American Journal of Epidemiology.