Trendy low carb diets such as Atkins, Paleo or Keto increases the risk of women having babies with spina bifida and other disabilities.
Pregnant women or those trying to conceive who avoid or restrict their carbohydrates have a 30 per cent higher risk of having babies with neural tube birth defects compared with women who do not restrict their carbohydrate intake.
Neural tube defects (NTDs) are the second most common severe disabling human congenital defects in the UK and include spina bifida which is the malformations of the spine and spinal cord and anencephaly with is the lethal absence of major portions of the brain and skull.
And the findings underscore the importance of dietary folic acid for pregnant women and those who could become pregnant, particularly as it is estimated over a sixth of UK births are unplanned.
Folic acid also known as vitamin B9 is an essential nutrient that minimises the risk of neural tube defects.
The Department of Health recommends that women should take a daily supplement of 400 micrograms of folic acid while they are trying to conceive, and should continue taking this dose for the first 12 weeks of pregnancy, when the baby's spine is developing.
Green vegetables and brown rice are rich in vital folic acid
Rich sources include green, leafy vegetables, brown rice, granary bread, and breakfast cereals fortified with folic acid.
The study by the University of North Carolina at Chapel Hill was first to evaluate the relationship between low carbohydrate intake and having children with neural tube defects.
And the findings underscore the importance of dietary folic acid for pregnant women and those who could become pregnant.
Research assistant professor Dr Tania Desrosiers said: "We already know that maternal diet before and during early pregnancy plays a significant role in foetal development.
"What is new about this study is its suggestion that low carbohydrate intake could increase the risk of having a baby with a neural tube defect by 30 per cent.
"This is concerning because low carbohydrate diets are fairly popular.
"This finding reinforces the importance for women who may become pregnant to talk to their health care provider about any special diets or eating behaviours they routinely practice."
The study analysed data from the National Birth Defects Prevention Study, which spanned 1998 to 2011 and included 11,285 pregnant women from Arkansas, California, Georgia, Iowa, Massachusetts, New York, North Carolina, Texas and Utah.
Of these women, 1,740 had infants, stillbirths or terminations with anencephaly or spina bifida while 9,545 had live born infants without birth defects.
It was found the dietary intake of folic acid among women with restricted carbohydrate intake was less than half of other women.
It is estimated a fifth of US women have blood folate concentrations below the recommended level to reduce risk of neural tube defects.
For this reason, in 1998 the Food and Drug Administration began requiring that folic acid be added to enriched grain products.
While women are urged to take folic acid supplements, up to half of pregnancies are unplanned and many do not start until they found out when a neural tube defect may have already occurred.
This makes fortified foods an important source of folic acid for women who may become pregnant.
The study was published in the journal Birth Defects Research.