Researchers have concluded that the products are a waste of money
Multivitamins aimed at pregnant women are an "unnecessary expense", a study has suggested.
The "heavily marketed" products for expectant women often contain more than 20 vitamins and minerals, and some carry slogans to say they provide "all the essential nutrients for pregnancy".
Researchers have concluded that these products are a waste of money, as there is no evidence to suggest that they bring better health for mother and child.
The detailed research, published in the UK-based Drug and Therapeutics Bulletin, saw experts assess the evidence on the benefits of folic acid, vitamin D, iron, vitamins C, E and A, as well as multivitamins during pregnancy.
Although there was substantial evidence to suggest that the use of folic acid could reduce the risk of conditions such as spina bifida, and "less clear cut" evidence which indicated vitamin D was beneficial, there was "no evidence" in support of multivitamins.
The authors of the report said: "Much of the evidence for vitamin supplementation in pregnancy comes from studies carried out in low-income countries, where women are more likely to be undernourished or malnourished than within the UK population."
Instead, mothers are being advised to take folic acid for the first trimester of their pregnancy, as well as vitamin D.
Pregnancy vitamins typically cost between €5 and €10 euro for a month's supply, whereas a three month's supply of folic acid or vitamin D can can be purchased for the same price.
A healthy diet is also recommended to keep women and their children healthy.