Research on Excessive Iodine Status in Pregnancy

Study Overview
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Brief Summary
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To explore main cause and health impact of iodine excess during pregnancy, we performed iodine evaluation for 390 consecutive pregnant women from January 1st, 2016 to December 31st, 2016. Among them, 18 women (4.62%) with apparently elevated urinary iodine concentration (UIC) were enrolled onto this study for subsequent follow-up. History of high iodine exposure was collected from all participants. Parameters about iodine status were monitors until termination of pregnancy, and dietary iodine intake condition and thyroid function were also evaluated.

Detailed Description
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A prospective follow-up was arranged for the 18 pregnant women with excessive iodine status. History of iodine exposure (including hysterosalpingography (HSG) using an oil-soluble iodinated contrast medium, examination by computed tomography scan with contrast, administration of amiodarone, history of receiving radioiodine therapy, etc.) was collected from all participants. Evaluation of dietary iodine intake was performed through a 72-hour dietary recall.The serum iodine concentration (SIC) and urinary iodine concentration (UIC) were monitored continuously in the whole course of pregnancy. All subjects with excessive iodine load were recommended by nutritionists to have their dietary iodine intake restricted, and resume iodine-containing supplements and foods until the UIC<250 μg/L and SIC≤90 μg/L. After delivery, maternal colostrum iodine concentration and neonatal iodine status (including neonatal UIC, condition of congenital hypothyroidism screening tests, and thyroid physical examination) were also assessed.

Official Title
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A Prospective Observational Study on Health Effect of Excessive Iodine Exposure in Pregnancy

Conditions
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Excessive Iodine Status, Thyroid Dysfunction, Antepartum, Pregnancy Related, Neonatal Disorder

Intervention / Treatment
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* Other: Dietary iodine intake restriction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant women with apparently elevated urinary iodine concentration (UIC ≥250μg/L) and serum iodine concentration (SIC>90μg/L) were enrolled in this study. Exclusion Criteria: Subject who did not sign the informed consent or whose clinical date was not intact was excluded in our study.
Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| HH group<br>Group (participants) with pre-gestational history of undergoing hysterosalpingography (HSG) using an oil-soluble iodinated contrast medium | Other: Dietary iodine intake restriction<br>* All subjects with excessive iodine load were recommended by nutritionists to restrict dietary iodine intake, and resume iodine-containing supplements and foods until their iodine status return to normal. However, in this observational study, the intervention was a regular management in prenatal care, and not assigned by investigator of the study.<br>|
| Non-HH group<br>Group (participants) without pre-gestational history of undergoing hysterosalpingography (HSG) | Other: Dietary iodine intake restriction<br>* All subjects with excessive iodine load were recommended by nutritionists to restrict dietary iodine intake, and resume iodine-containing supplements and foods until their iodine status return to normal. However, in this observational study, the intervention was a regular management in prenatal care, and not assigned by investigator of the study.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| prevalence of adverse pregnancy outcome | prevalence of stillbirth, abortion and other adverse pregnancy outcome | 6-9 months post identification of maternal iodine excess | 
| composite neonatal outcome | Apgar scores, birth weight of the neonates,and prevalence of thyroid dysfunction in neonates | 6-9 months post identification of maternal iodine excess | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| prevalence of maternal thyroid dysfunction in pregnancy | Laboratory reference ranges of TSH during pregnancy were 0.1 2.5 mIU/L for the first trimester, 0.2 3.0 mIU/L for the second trimester and 0.3 3.0 mIU/L for the third trimester.Prevalence of TSH elevation during pregnancy will be summarized. | through study completion, about 6-9 months post identification of maternal iodine excess | 
| prevalence of neonatal iodine excess | urinary iodine concentration will be examined for all neonates born to women with iodine excess in pregnancy, and prevalence of neonatal urinary iodine concentration ≥ 200μg/L will be summarized. | within 1 week after birth | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Iodine excess, Cause, Pregnancy, Urinary iodine concentration, Serum iodine concentration, Breast milk iodine concentration