Research has shown that expensive multivitamins are not necessary during pregnancy.
In the Drug and Therapeutics Bulletin, researchers say they looked at all evidence and found that branded multivitamin supplements did not boost the health of mothers and babies.
Pregnancy supplements typically contain more than 20 vitamins and minerals, including vitamins B1, B2, B3, B6, B12, C, D, E, K, folic acid, iodine, magnesium, iron, copper, zinc and selenium. They cost about £15 a month.
The researchers added that pregnant women should make sure they take folic acid and Vitamin D, which are available at relatively low cost, often own branded, from pharmacies or supermarkets, as well as eating a well-balanced diet.
What you really need: vital pregnancy supplements
The researchers said folic acid had the strongest evidence to support its use - taking 400 micrograms a day can protect against abnormalities called neural tube defects in the developing baby. Some groups, including women with a BMI over 30, should get a prescription from their doctor to take a higher dose of 5mg.
Vitamin D - 10 micrograms a day - is recommended for healthy bones in the mother and baby.
Bought together, a month's supply of these two pills will typically set you back around £3, and some women can get them for free on the Healthy Start scheme.
Tommy's midwife Sophie says:
"We know that having a balanced, varied diet and appropriately sized meal portions will contain almost all of the nutrients and vitamins that their bodies need for a healthy pregnancy. We want mums to know that they do not need to spend a lot of money on unnecessary supplements when these can naturally be found in the fresh food that they buy."
Find out more about why folic acid and Vitamin D are such important supplements to take in pregnancy.
Eating for two?
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."
In pregnancy, your baby takes everything they need from you for the first six months without you needing any extra calories at all. Once you get to the last trimester, you may need to eat a bit more. This is only around 200 extra calories a day, though, which is around half a sandwich.