Iodine deficiency in pregnancy and the effects of maternal iodine on offspring

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Methyl Donors, Iodine, and Docosahexaenoic Acid (DHA)--Is Maternal

Supplementation Beneficial?

Iodine deficiency in pregnancy and the effects of maternal iodine

supplementation on the offspring: a review 1,2,3

B Zimmermann

1 From the Human Nutrition Laboratory, Swiss Federal Institute of

Technology Zürich, Switzerland, and the Division of Human Nutrition,

Wageningen University, Wageningen, Netherlands.

2 Supported by the Swiss Foundation for Nutrition Research and the

Swiss Federal Institute of Technology (Zurich, Switzerland).

3 Reprints not available. Address correspondence to M Zimmermann,

Human Nutrition Laboratory, Swiss Federal Institute of Technology

Zentrum, Schmelzbergstrasse 7, LFV E19, CH-8092 Zürich, Switzerland.

E-mail: michael.zimmermann@....

ABSTRACT

The World Health Organization (WHO) recently increased their

recommended iodine intake during pregnancy from 200 to 250 µg/d and

suggested that a median urinary iodine (UI) concentration of 150–249

µg/L indicates adequate iodine intake in pregnant women. Thyrotropin

concentrations in blood collected from newborns 3–4 d after birth may

be a sensitive indicator of even mild iodine deficiency during late

pregnancy; a <3% frequency of thyrotropin values >5 mU/L indicates

iodine sufficiency. New reference data and a simple collection system

may facilitate use of the median UI concentration as an indicator of

iodine status in newborns. In areas of severe iodine deficiency,

maternal and fetal hypothyroxinemia can cause cretinism and adversely

affect cognitive development in children; to prevent fetal damage,

iodine should be given before or early in pregnancy. Whether mild-to-

moderate maternal iodine deficiency produces more subtle changes in

cognitive function in offspring is unclear; no controlled

intervention studies have measured long-term clinical outcomes. Cross-

sectional studies have, with few exceptions, reported impaired

intellectual function and motor skills in children from iodine-

deficient areas, but many of these studies were likely confounded by

other factors that affect child development. In countries or regions

where <90% of households are using iodized salt and the median UI

concentration in school-age children is <100 µg/L, the WHO recommends

iodine supplementation in pregnancy and infancy.

http://www.ajcn.org/cgi/content/abstract/ajcn.2008.26811Cv1

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