"Folic acid is important because it can help to prevent birth defects of a baby's brain and spine, such as spina bifida. Spina bifida can cause walking, bladder and bowel problems."
The website also states that iodine helps the body to grow and develop, especially the brain.
"Because babies get iodine from their mothers, pregnant and breastfeeding women need more iodine."
Despite this, pharmacy staff often recommended the shopper in the Consumer NZ test take multivitamin supplements, including Elevit and Blackmores Conceive Well Gold which, on a daily basis, are at least seven times more expensive than plain folic acid.
Chetwin said there was little evidence spending extra money on a pregnancy multivitamin compared with plain folic acid and iodine improves a woman's health or that of her baby.
"Would-be mums would be better off using that money to buy healthy foods," Chetwin said.
Some women taking pregnancy multivitamins experience uncomfortable side effects, she said.
"Most products contain iron, even though obstetricians say it's only necessary for women with anaemia.
"Women with healthy levels of the mineral unnecessarily risk suffering pain, constipation and vomiting.
"Pharmacy staff should base their advice to customers on the best available science, particularly when they recommend a more expensive product," she said.
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists' guidelines state a well-balanced diet – alongside folic acid and iodine tablets – is the best way for the average woman to meet her body's nutritional needs in pregnancy, unless her doctor recommends otherwise.
Consumer NZ also conducted a product survey of supplements marketed to would-be mums. Despite the Ministry of Health advising an 800µg per day dose of folic acid, some products contained just 300µg.
