The findings, published in the American Journal of Clinical Nutrition, suggest that improving the diet of women in impoverished nations, or encouraging intake of vitamin E through prenatal supplements could have a direct impact on fertility.
Indeed, the new study found that pregnant women in Bangladesh with low levels of the most common form of vitamin E are nearly twice as likely to have a miscarriage than those with adequate levels of the vitamin in their blood.
"For nearly a century, we have known about vitamin E and its role in the fertility of animals," commented one of the study leaders, Kerry Schulze from Johns Hopkins Bloomberg School of Public Health. "To our knowledge, this is the first study in humans that has looked at the association of vitamin E and miscarriage.”
“The findings from this study support a role for vitamin E in protecting the embryo and foetus in pregnancy."
The researchers analysed data from 1,605 rural Bangladeshi pregnant women in the JiVitA-1 study that ran from 2001 to 2007.
Blood samples were taken upon enrolment in the first trimester and any miscarriages were recorded on a weekly basis thereafter. Of the 1,605 women in the study, 141 (8.8%) subsequently miscarried, said the team.
The researchers looked at two forms of vitamin E - alpha-tocopherol (the most active form of the vitamin in the body) and gamma-tocopherol.
Nearly three out of four women in the study had what was considered vitamin E deficiency, with low alpha-tocopherol levels, they said. Indeed, when looking at alpha-tocopherol, 5.2% of women with adequate levels in their blood miscarried in the first or second trimester as compared with 10.2% of women who miscarried with low levels.
The relationship with gamma-tocopherol, however, went the other way, with higher levels associated with increased miscarriage risk, though to a lesser degree, said Schulze.
Pregnant women in developing countries are traditionally not typically given or advised to take a prenatal multivitamin before or after becoming pregnant. Instead, the current standard of care is to provide iron and folic acid supplements, because of the proven links between deficiencies of those nutrients and poor pregnancy outcomes, noted the research team.
"The new findings suggest that having pregnant women consume an adequate amount of vitamin E early in pregnancy could be beneficial," said Abu Ahmed Shamim from the Bloomberg School.
However he added that since miscarriages occur so early in pregnancy, levels of vitamin E ideally need to be boosted in women of childbearing age by improving access to a diverse diet that includes better vitamin E sources - so they already have what they need once they become pregnant.
"Vitamin deficiencies are considered a form of hidden hunger because they are not readily apparent but they can have huge health consequences," explained Schulze.
"What we really want to do is optimise health before women become pregnant, because if they don't start with a good vitamin E status, they are at a high risk of negative outcomes."
Schulze added that the study may not be generalizable to higher-income nations where women of childbearing age tend to have better nutritional status.