Swedish Iodine in Pregnancy and Development in Children (SWIDDICH) Study (SWIDDICH)
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ClinicalTrials.gov Identifier: NCT02378246 |
Recruitment Status :
Recruiting
First Posted : March 4, 2015
Last Update Posted : September 20, 2021
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THE ULTIMATE GOAL of this project is to answer the question "In MILD IODINE DEFICIENCY (ID), should 150 μg iodine/day be administered to pregnant women with a normal diet, to attain a normal cognitive development of the fetus or is there no cognitive deficit from mild ID and no extra iodine is needed?". To answer this question, the investigators planned a randomized, placebo-controlled trial of iodine supplementation during pregnancy in Sweden (SWIDDICH) with the follow-up of childrens' COGNITIVE DEVELOPMENT at 18 months, 3.5, 7 and 14 years.
Iodine deficiency (ID) is associated with thyroid morbidity and, especially in children, with impaired cognitive development. Sweden introduced iodine fortification of table salt 1936 and mental retardation due to severe ID is eradicated. Is mild ID during pregnancy also eradicated? If not, is this of importance? A national study performed by the investigators in 2007 showed iodine sufficiency in general population, but there are no pregnancy data. Local studies have raised concerns for mild ID during pregnancy in Sweden and a trans-sectional national study is currently ongoing.
The burning question for Sweden and the whole world is: is mild ID during pregnancy of importance for the developing brain of the fetus? Two large observational studies have shown association between mild ID during pregnancy and lower verbal IQ or educational performance at school-aged children. The world needs a randomized placebo-controlled trial (RTC) comparing the cognitive outcome in children exposed to mild ID during fetal life with children exposed to normal iodine levels during fetal life.
Our HYPOTHESIS is that pregnant women in Sweden have mild ID and that children exposed to mild ID during fetal life have a lower cognitive development, compared to children to mothers taking 150 ug iodine supplementation during pregnancy.
The MAIN AIM of the SWIDDICH trial is to determine if children exposed to mild iodine deficiency (ID) during fetal life achieve worse cognitive development compared to children exposed to normal iodine status reached by maternal iodine supplementation.
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Thyroid Gland; Node Pregnancy Cognitive Developmental Delay | Dietary Supplement: Iodine Dietary Supplement: Placebo | Not Applicable |

Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 1275 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Triple (Participant, Care Provider, Outcomes Assessor) |
Primary Purpose: | Prevention |
Official Title: | The Importance of Iodine During Pregnancy for Future Brain Function : a Randomized Placebo-controlled Trial. Swedish Iodine in Pregnancy and Development in Children (SWIDDICH) Study |
Actual Study Start Date : | November 2012 |
Estimated Primary Completion Date : | June 2025 |
Estimated Study Completion Date : | June 2032 |

Arm | Intervention/treatment |
---|---|
Experimental: Iodine containing multivitamin
multivitamin tablet containing 150 ug iodine, 1 tablet daily
|
Dietary Supplement: Iodine
We use multivitamin tablets one with 150 microgram iodine for Active comparator and one without iodine as placebo |
Placebo Comparator: Placebo: non-iodine containing multivitamin
non-iodine containing multivitamin, 1 tablet daily
|
Dietary Supplement: Placebo
multivitamin tablets without iodine |
- Intelligence quotient (IQ) at 3.5 years, WPPSI IV [ Time Frame: when the child is at the age of 3,5 years ± 2 months ]Wechsler Preschool and Primary Scale of Intelligence - Fourth Edition; IQ with sub-domains
- Psychomotor development at 18 months, ASQ-3 [ Time Frame: when the child is at the age of 18 months ± 1 month ]Ages & Stages Questionnaire - Third Edition; a questionnaire filled in by parents
- Intelligence quotient (IQ) at 7 years, WISC IV [ Time Frame: when the child is at the age of 7 years ± 3 months ]Wechsler Intelligence Scale for Children - Fourth Edition; IQ with sub-domains
- Intelligence quotient (IQ) at 14 years, WISC IV [ Time Frame: when the child is at the age of 14 years ± 6 months ]Wechsler Intelligence Scale for Children - Fourth Edition; IQ with sub-domains
- Behavioral problems at 3.5 years, CBCL [ Time Frame: when the child is at the age of 3,5 years ± 2 months ]Child Behavior Checklist questionnaire filled in by parents
- Behavioral problems at 7 years, CBCL [ Time Frame: when the child is at the age of 7 years ± 3 months ]Child Behavior Checklist questionnaire filled in by parents
- Behavioral problems at 14 years, CBCL [ Time Frame: when the child is at the age of 14 years ± 6 months ]Child Behavior Checklist questionnaire filled in by parents
- ADHD-related problems at 7 years, FTF [ Time Frame: when the child is at the age of 7 years ± 3 months ]Nordic Questionnaire 5-15 (FTF) filled in by parents
- ADHD-related problems at 14 years, FTF [ Time Frame: when the child is at the age of 14 years ± 6 months ]Nordic Questionnaire 5-15 (FTF) filled in by parents
- Motor skills at 7 years, Movement ABC [ Time Frame: when the child is at the age of 7 years ± 3 months ]Movement ABC test performed by a physiotherapist
- Brain development at 7 years, MRI [ Time Frame: when the child is at the age of 7 years ± 3 months ]Magnetic Resonance Imaging; manual and automatic volumetry
- Brain development at 7 years, MRI [ Time Frame: when the child is at the age of 14 years ± 6 months ]Magnetic Resonance Imaging; manual and automatic volumetry
- Urinary iodine concentration (UIC) in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]
- Urinary iodine concentration (UIC) in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]
- Urinary iodine concentration (UIC) in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]
- Thyreoglobulin concentration in serum, in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]
- Thyreoglobulin in serum, in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]
- Thyreoglobulin in serum, in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]
- Thyroid stimulating hormon concentration in serum, in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]
- Thyroid stimulating hormon concentration in serum, in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]
- Thyroid stimulating hormon concentration in serum, in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]
- Free thyroxine concentration in serum, in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]
- Free thyroxine concentration in serum, in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]
- Free thyroxine concentration in serum, in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]Free thyroxine concentration, serum
- Anti-TPO in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]Thyroid peroxidase antibody titer, plasma
- Anti-TPO in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]Thyroid peroxidase antibody titer, plasma
- Anti-TPO in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]Thyroid peroxidase antibody titer, plasma
- B12 in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]Vitamin B12, serum
- B12 in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]Vitamin B12, serum
- B12 in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]Vitamin B12, serum
- Selenium in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]Selenium, serum
- Selenium in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]Selenium, serum
- Selenium in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]Selenium, serum
- Iron in the mother, 1st trimester [ Time Frame: 10±2 weeks (pregnancy) ]Iron, serum
- Iron in the mother, 2nd trimester [ Time Frame: 26±2 weeks (pregnancy) ]Iron, serum
- Iron in the mother, 3rd trimester [ Time Frame: 36±2 weeks (pregnancy) ]Iron, serum
- Milk iodine concentration (MIC) in colostrum [ Time Frame: within 5 days after delivery ]
- Urinary iodine concentration (UIC) in the newborn [ Time Frame: within 5 days after delivery ]
- Urinary iodine concentration (UIC) in the mother [ Time Frame: within 5 days after delivery ]
- Urinary iodine concentration (UIC) at 3.5 years [ Time Frame: when the child is at the age of 3,5 years ± 2 months ]
- Urinary iodine concentration (UIC) at 7 years [ Time Frame: when the child is at the age of 7 years ± 3 months ]
- Urinary iodine concentration (UIC) at 14 years [ Time Frame: when the child is at the age of 14 years ± 6 months ]
- Thyroid stimulating hormone, dry blood spot (DBS), in the newborn [ Time Frame: within 5 days after delivery ]
- TSH at 7 years [ Time Frame: when the child is at the age of 7 years ± 3 months ]Thyroid stimulating hormone, dry blood spot (DBS)
- TSH at 14 years [ Time Frame: when the child is at the age of 14 years ± 6 months ]Thyroid stimulating hormone, dry blood spot (DBS)
- TG at 7 years [ Time Frame: when the child is at the age of 7 years ± 3 months ]Thyreoglobulin, dry blood spot (DBS)
- TG at 14 years [ Time Frame: when the child is at the age of 14 years ± 6 months ]Thyreoglobulin, dry blood spot (DBS)
- FT4 at 7 years [ Time Frame: when the child is at the age of 7 years ± 3 months ]Free thyroxine, dry blood spot (DBS)
- FT4 at 14 years [ Time Frame: when the child is at the age of 14 years ± 6 months ]Free thyroxine, dry blood spot (DBS)
- Deiodinases at 7 years [ Time Frame: when the child is at the age of 7 years ± 3 months ]Dry blood spot (DBS)
- Deiodinases at 14 years [ Time Frame: when the child is at the age of 14 years ± 6 months ]Dry blood spot (DBS)

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Ages Eligible for Study: | 18 Years to 40 Years (Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | No |
PREGNANT WOMEN
Inclusion criteria
- Pregnant, week <13
- Age 18-40 years
- Intent of a full term pregnancy
- Agreement of taking no iodide containing supplements during the study except for study supplement
Exclusion Criteria
- Known current thyroid disease
- Risk factors for thyroid disease (history or heredity for thyroid, other autoimmune disease or symptoms of hypo-/hyperthyroidism) where the TSH is abnormal
- Possibility to not attend to the protocol according to the investigator's opinion
- Less than 6 months from previous pregnancy or lactating period
- Vegan
CONTROL WOMEN
Inclusion criteria
- Age 18-40 years
- Agreeing not to take iodide containing supplements 1 week prior to the collecting of the samples.
Exclusion criteria
- Current thyroid disease
- Risk factors for thyroid disease (history or heredity for thyroid or other autoimmune disease or symptoms of hypo-/hyperthyroidism) where the TSH is abnormal
- Possibility to not attend to the protocol according to the investigator's opinion
- Currently pregnant or lactating
- Less than 6 months from previous pregnancy or lactating period
- Vegans

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02378246
Contact: Sofia Manousou, PhD student | +46700595310 | sofia.manousou@vgergion.se | |
Contact: Helena Filipsson, Ass Prof | 0046-705833398 | helena.nystrom@vgregion.se |
Sweden | |
Umeå Universitet, Department of Clinical Sciences | Recruiting |
Umea, Västerbotten, Sweden, 901 85 | |
Contact: Magnus Domellöf, Professor 090-7852128 magnus.domellof@umu.se | |
Contact: Anna Chmielewska, MD, PhD 090-7852370 anna.chmielewska@umu.se | |
Sahlgrenska University Hospital | Recruiting |
Gothenburg, Sweden, 413 45 | |
Contact: Helena Filipsson, MD, PhD 0705-833398 helena.filipsson@gu.se | |
Contact: Sofia Manousou, MD 0700-5953310 sofia.manousou@vgregion.se | |
Sub-Investigator: Lena Hulthén, Senior Prof | |
Sub-Investigator: Robert Eggertsen, Prof | |
Principal Investigator: Helena Filipsson Nyström, Ass Prof | |
Sub-Investigator: Carl-Johan Törnhage, Docent | |
Sub-Investigator: Birgitta Johansson, Docent | |
Sub-Investigator: Helge Malmgren, Senior Prof | |
Linköping University Hospital | Not yet recruiting |
Linkoping, Sweden | |
Contact: Kerstin Gutefeldt | |
Completed | |
Skövde, Sweden |
Principal Investigator: | Helena Filipsson Nyström, Ass Prof | Center for Endocrinology and Metabolism, SAhlgrenska University Hospital |
Responsible Party: | Göteborg University |
ClinicalTrials.gov Identifier: | NCT02378246 |
Other Study ID Numbers: |
13031305 |
First Posted: | March 4, 2015 Key Record Dates |
Last Update Posted: | September 20, 2021 |
Last Verified: | September 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Undecided |
Plan Description: | This has not yet been discussed by the study group. |
Iodine Double-Blind Method Randomized Controlled Tria Cognitive Development |