Soon-to-be Brisbane mum-of-three Stephanie Davis assumed everyone took multivitamins during pregnancy.
However new research shows using supplements 'just in case' could do more harm than good for mother and baby.
"It's quite concerning that there's potential harm in taking them," Ms Davis says.
In her first two pregnancies, she took a popular prenatal supplement to ensure she had enough folic acid.
"I just knew I had to have folic acid and you go to the shelves and see, well, 'this one is for pregnancy so I must need all the other vitamins as well'," she says.
Ms Davis was the first among her friends and sisters to have a baby so didn't have anyone close for advice.
Her general practitioner didn't steer her either way into taking or not taking multivitamins and just told her to take folic acid.
"I told them, 'Oh, I'm taking this which has folic acid in it' and they were like, 'Yeah that's fine'. They didn't really question, 'Oh, you know, do you need to be taking all those other supplements?'
Prenatal multivitamins contain a range of supplements including folic acid, iron, iodine, calcium, zinc, magnesium, copper and others.
A study has found many Australian women are putting faith in supplements to ensure they meet pregnancy requirements for folic acid and iron but are already getting plenty of these nutrients from their diet.
"Just taking supplements as a safeguard can come with risks," says University of Sunshine Coast lead author Dr Linda Gallo.
Excess nutrients can lead to gestational diabetes, pre-eclampsia, irregular birth weights, preterm birth and poorer neurodevelopmental outcomes in the baby.
The research has found high-income women who receive private obstetric care, have private health insurance and consume meat and vegetables are more likely to take supplements 'just in case'.
"A common motivating factor ... is just that peace of mind that nutritional needs are being met," Dr Gallo says.
She emphasises that women are not to blame for taking the supplements, but more scrutiny should apply to marketing pushes and existing health advice.
According to Associate Professor Shelley Wilkinson of Mater Research, women who do not have a deficiency should only be taking an extra 400 micrograms of folic acid until the second trimester and 150 micrograms of iodine.
She says multivitamins contain a plethora of supplements not deemed necessary before or during pregnancy.
It's important to note some women will be recommended supplements by their doctor if they have a diagnosed deficiency.
The study authors say a comprehensive diet meeting all the food groups is more beneficial for mother and baby than taking multivitamins as a back-up.
"There are many beneficial aspects of a whole food diet that we can't get from supplements alone," Dr Gallo says.
During pregnancy, women are advised to eat whole fruits and vegetables of different types and colours, dairy or calcium-enriched alternatives, increased serves of wholegrains and iron-rich foods such as lean red meat or tofu.
In Ms Davis' third pregnancy, she has focused on her food intake.
"This time around I can invest a little bit more into my health and I feel really good that I'm covered on all bases," she says.
After suffering post-natal depression with her first little girl, she is hoping consuming a whole-food diet will help curb any anxiety and depression this time around.
Dietician Kate Save has also recommended blood tests to monitor levels of nutrients to guide her diet.
"Dieticians can conduct a genetic screening which allows you to understand your individual absorption capabilities and nutritional status," Ms Save says.
"They can provide tailored supplementation to ensure the right dose of nutrients like folate, as well as a balanced diet plan."
Different women will have different approaches to their pregnancy but this research shows multivitamins may not be the first answer.
Dr Gallo says there should be an overhaul of what healthcare providers recommend regarding multivitamins and encouragement for dietitians to play a bigger role during pregnancy.
AAP approached Queensland Health for comment.
