Research on Excessive Iodine Status in Pregnancy

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

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.

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.

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.