Opting for a vegetarian or vegan diet could be preventing women from getting all the nutrients they need for a healthy pregnancy, research suggests.
Most women are not consuming the essential vitamins they need and this could worsen as more people opt for plant-based diets, a study found.
The study explored the vitamin status of 1,729 women from the UK, Singapore and New Zealand.
It specifically looked for vitamins found in meat and dairy products, such as vitamins D, B12 and B6, folic acid and riboflavin.
Folic acid and B12 help prevent birth defects such as spina bifida, vitamin D helps to keep bones, teeth and muscles healthy, and riboflavin supports the growth of bone, muscle and nerves in babies in the womb.
Researchers found that more than 90% of the group had marginal or low concentrations of one or more of the vitamins, with many developing markers of B6 deficiency in late pregnancy.
Keith Godfrey, lead author of the study and professor of epidemiology at the University of Southampton, said: “The push to reduce our dependence on meat and dairy to achieve net-zero carbon emissions is likely to further deplete expecting mothers of vital nutrients, which could have lasting effects on unborn children.”
The cohort was divided into two; an intervention group of 870 women and a control group of 859 women.
Both groups received supplements containing 400mg folic acid, 12mg iron, 150mg calcium, 150mg iodine and 720mg beta-carotene.
However, the control group’s supplement also included 1.8mg riboflavin, 2.6 mg vitamin B6, 5.2mg vitamin B12, 10mg vitamin D and 10mg zinc, as well as myo-inositol and probiotics.
Blood samples were collected prior to conception, early pregnancy, late pregnancy and six months after their babies were born.
Researchers said the amount of vitamins available in over-the-counter products “substantially reduced the prevalence of deficiency” before and during pregnancy.
They added: “In the setting of increasing advocacy for more diets that are likely to be less nutrient dense, the findings suggest a need to reappraise dietary recommendations for preconception and pregnancy and to consider further the role of multiple micronutrient supplements in women living in higher-income countries.”
According to NHS England, women hoping to get pregnant should take 400mg of folic acid every day from before pregnancy until they are 12 weeks pregnant to reduce the risk of problems with their baby’s development.
A daily vitamin D supplement is also recommended.
Prof Godfrey added: “Our study shows that almost every woman trying to conceive had insufficient levels of one or more vitamin, and this figure is only going to get worse as the world moves towards plant-based diets.
“People think that nutrient deficiency only affects people in underdeveloped countries – but it is also affecting the majority of women living in high-income nations.”
Professor Ian Givens, director of the Institute for Food, Nutrition and Health at the University of Reading, said: “This study is very timely and should provide the impetus to reassess dietary provision of key nutrients before and during pregnancy.
“In UK omnivores, dairy foods, meat and fish provide about 80% of dietary vitamin B12 and meat, eggs and fish provide about 65% of dietary vitamin D although dietary supply only provides about three micrograms per day, meaning that supplementary vitamin D is necessary.
“As the authors suggest, the current trend towards diets with animal-derived foods being at least partially replaced by plant-based foods will further increase the risk of sub-optimal status of vitamin B12 and D (and other nutrients) in women of childbearing age. This needs to be considered when such dietary transition is contemplated.”
The findings have been published in PLOS Medicine.
The team was led by academics from the University of Southampton and supported by the National Institute for Health and Care Research (NIHR) Biomedical Research Centre, the University of Auckland, National University of Singapore, and the Agency for Science, Research and Technology in Singapore.