About the study

SWIDDICH is a national study that comprises several communities in Sweden to answer the question “Can iodine substitution improve children’s development?” To be able to do this, every participating family is important as we need to recruit 1275 pregnant women (all participators are randomised into two groups where both will be given a tablet with multiple vitamins, but in one group the tablet also contains 150 µg iodine and in the other control group, the vitamin tablet is without iodine).

Why the SWIDDICH study?

Our goal is to have healthy and prosperous children and we know that iodine is important for the function of the thyroid gland. Iodine is found in dairy products, fish and seafood, and iodine enriched table salt. Studies have shown that there is no dangerous iodine insufficiency in Sweden today even if iodine intake has decreased in the population during the last few decades. The SWIDDICH study will investigate what importance an iodine substitution during pregnancy has for the children’s health. We will therefore follow the children’s health during their development.

What will be examined?

Initially you, in early pregnancy, will be prescribed a vitamin tablet with or without iodine to be taken daily until delivery. During the pregnancy, laboratory tests of iodine and thyroid gland hormones will be measured on different occasions. After delivery, we will follow the children with a strong focus on cognitive development. Iodine is important for the brain’s development during fetal life which is why the children will be examined by a psychologist who will evaluate the children’s cognitive ability. The parents will fill in a questionnaire about their child’s behaviour. We are also interested in the children’s laboratory tests of iodine, thyroid gland hormones, and related factors. In addition, we will collect information regarding circumstances that can influence the iodine level with the help of a questionnaire.

Supplementary information regarding the parents/caregivers and the child’s health and living conditions will be collected. Facts about the children and the pregnancy will be collected from medical records of hospitals, primary care centres, maternity care centres, child care centres, school health care, and from National Quality Registers (Pregnancy Record Register, Swedish National Neonatal, Child Care and School Care Quality Register), National Board of Health and Welfare (The National Patient Register, The Swedish Prescribed Drugs Register, The Swedish Birth Register) and Statistics Sweden (population registration and facts including education and study results). All collections are approved by the Swedish Ethical Review Authority and no participators will be personally identified in published research results.

Can we participate?

To be able to join the study you must as a future mother:

  • be between 18-40 years old
  • be in the early stages of pregnancy (week 13 or less)
  • not have a disease of the thyroid gland
  • not have been pregnant, had a miscarriage, or been breastfeeding in the last 6 months
  • not be vegan

If you have heredity thyroid gland diseases, earlier history of thyroid gland disease, have other autoimmune diseases or symptoms of thyroid gland disease, the laboratory blood test performed at the Maternity Care Centre must be normal.

Since the study means that you can be prescribed a dietary supplement containing iodine, you must refrain from taking other multiple vitamins until delivery. You can take supplements of folic acid and iron beyond the prescribed dietary supplement.

Are you interested? Leave your contact details here.

For more information click here.