Barely a third of New Zealand mums are adhering fully to Ministry of Health recommendations about boosting their iodine and folic acid intake, an Otago University study has shown.
The researchers note that the ministry rarely recommends using supplements, but does offer advice about taking in additional iodine and folic acid to avoid neurodevelopmental problems in babies.
Women considering pregnancy, who are pregnant, or who are breastfeeding are urged to take an iodine supplement each day containing 150mcg of the trace mineral.
The ministry also recommends that one folic acid tablet (0.8 mg) be taken daily for four weeks before conception through to 12 weeks after becoming pregnant.
The Otago study looked at survey responses from 535 women from around the country who were pregnant, or had been pregnant over the past two years.
Lead author Dr Andrew Reynolds says only 52 per cent followed the iodine advice.
Just 38 per cent followed both the iodine and the folic acid recommendation.
Co-author Associate Professor Sheila Skeaff says a bigger effort needs to be made to promote the recommendations and increase access to iodine and folic acid supplements.
"We want communities to know about these nutrients, and why they are important," she said.
Iodine is important for optimal foetal and infant brain development, including IQ later in life, while folic acid helps prevent neural tube defects in babies.
The study has been published in the Australian and New Zealand Journal of Obstetrics and Gynaecology.