Iodine supplementation in pregnant women living in mild-tomoderately iodine deficient areas in India and Thailand: effects on pregnancy outcome and infant development
Zimmermann, Michael B.
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Rationale: In regions of severe endemic goiter, the adverse effects of in utero iodine deficiency on neuromotor development are well established: randomized controlled trials of iodine supplements given to iodine deficient mothers before pregnancy or during early pregnancy improve motor and cognitive performance of their offspring. However, the potential adverse effects of mild-to-moderate iodine deficiency during pregnancy are unclear. Inadequate thyroid function in the fetus and newborn are the likely cause of brain damage in iodine deficiency.Objective: To determine whether the daily oral administration of 200 μg iodine to pregnant women in areas of mild-to-moderate iodine deficiency improves maternal and newborn thyroid function, pregnancy outcome, birth weight, infant growth and cognitive performance.Study design: Double-blind randomized controlled multicentre trial.Study population: Pregnant women (18-40 years) presenting at the clinic for their first prenatal visit will be recruited at two research sites, namely St. Martha's hospital in Bangalore, India and Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. At each site, 400 women will be recruited.Intervention: Half of the women will be randomized to iodine treatment (200 μg per day) and the other half to placebo throughout pregnancy.Main study parameters/endpoints: Differences between group means in indicators of thyroid function, birth outcome, urinary iodine, breast milk iodine, growth, and psychomotor development.Nature and extent of the burden and risks associated with participation, benefit and group relatedness: In 2004, the dose, safety and efficacy of iodine supplementation in mild to moderately iodine-deficient pregnant women were reviewed from 6 European trials. In all 6 trials, supplementation resulted in a significant increase in maternal urinary iodine. Iodine doses varied between 50 and 230 μg per day, and the data indicate no clear dose response relationship for urinary iodine or parameters of thyroid function. Iodine supplements during pregnancy appeared to be generally safe; there was no increase in maternal thyroid autoimmunity, or in the prevalence or severity of postpartum thyroid dysfunction (PPTD) in the trials. For the newborn, most data suggest supplementation is safe, although increases in cord blood TSH upon maternal iodine supplementation have been reported, which are probably transient but which have not been followed up until now.So far, no studies have been conducted in mild-to-moderate iodine deficient areas in which the effects of maternal iodine supplementation on child development have been followed up. Worldwide, millions of children are born each year unprotected against the damaging effects of mild iodine deficiency. This large multicentre study will provide conclusive evidence on the global need for iodine supplementation during pregnancy in countries where moderate-to-mild iodine deficiency is prevalent Show more
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Organisational unit03957 - Zimmermann, Michael
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