"The only supplements recommended for all women during pregnancy are folic acid and vitamin D, which are available at relatively low cost," researchers have said.
Pregnant women might often feel compelled to buy expensive multivitamins in order to give their baby the best start in life.
But in Drug and Therapeutics Bulletin, researchers say they looked at all evidence and found supplements did not boost the health of mothers and babies.
"The only supplements recommended for all women during pregnancy are folic acid and vitamin D, which are available at relatively low cost," they said.
Janet Fyle, from the Royal College of Midwives, said: "We would encourage women who are pregnant or are thinking of becoming pregnant to have a healthy, varied diet including fresh fruit and vegetables, alongside taking folic acid supplements.
"We would also stress that there is no need for pregnant women to 'eat for two'.
"This is a myth, and all that is required is a normal balanced amount of food."
However, researchers stressed that pregnant women should make sure they take folic acid and vitamin D, as well as eating a well-balanced diet.
According to them, taking 400 micrograms of folic acid a day can protect against abnormalities called neural tube defects in the developing baby.
Vitamin A, which is also a supplement, can also be dangerous for the developing baby, the researchers added.