Maternal iodine deficiency

Various maternal metabolic dysfunctions can cause fetal cerebral palsy. An example is maternal iodine deficiency and resulting hypothyroxinemia (abnormally low concentration of blood thyroxine). 

The observations relating to iodine deficiency in pregnancy are firstly those concerned with maternal thyroid function and maternal goiter. Maternal urinary iodine (UI) excretion is the usual method of assessing iodine status in the population at risk or the individual, and is discussed below. Neonatal indicators of maternal iodine deficiency are goiter and neurointellectual impairment. 

Figure 108.1 Human fetal and neonatal hypothyroid syndromes iodine defioienoy and endemic cretinism. If environmental iodine deoreases, maternal iodine deficiency in early pregnancy will not provide the fetal thyroxine required for neural development. Insuffioient supply of iodine leads to fetal and neonatal hypothyroidism.

The two most recent NHANES surveys showed that for women of childbearing age and pregnant women, the median UI excretion levels were adequate (127 and I4lpg/1, respectively, in 1988-1994 132 and 173 pg/1, respectively, in 2001-2002) (Table 115.3) (Caldwell et al., 2005). Thyroid hormone, requiring adequate iodine intake, is critical for neural development in utero and in early life. Although cretinism due to iodine deficiency is not a problem in the United States, subtle developmental delays could result from mild maternal iodine deficiency. 

We use iodized salt to prevent goiters and mental retardation. In China, a country of 1.2 billion people, there are 10 million cases of retardation from lack of iodine. Although just trace amounts would prevent this, many people buy noniodized salt on the black market to save money. Maternal iodine deficiency results in growth and brain impairment in the child. 

Escobar del Rey F, Pastor R, Mallol J, Morreale de Escobar G, Effects of maternal iodine deficiency on the L-Thyroxine and... 

Escobar del Rey F, Pastor R, Mallol J, Morreale de Escobar G, Effects of maternal iodine deficiency on the L-Thyroxine and 3,5,3 -Triiodo-L-Thyronine contents of rat embryonic tissues before and after onset of fetal thyroid function. Endocrinology 118 1259 (1986)... 

The data suggesting the direct role of elemental iodine on brain development is the observation that correction of iodine deficiency in mothers prevents the emergence of neurological cretinism only if correction takes place before or during early gestation, thus before the onset of fetal thyroid function (83). What we would like to know in greater detail is which parameter is corrected in the human fetus when maternal iodine deficiency is corrected before the onset of fetal thyroid function Is it the fetal deficiency in iodine, in thyroid hormones or in both ... 

F. Escobar del Rey, R.M Pastor, J. Mallol, and G. Morreale de Escobar, Effects of maternal iodine deficiency on... 

Another example of a maternal condition that contributes to birth defects is low circulating iodine. Cretinism is one of the most profound, but completely preventable, syndromes of malformation known. Characteristic consequences of prenatal iodine deficiency include pervasive mental and physical retardation, deaf-mutism (due to primary malformation of the inner ear), lack of muscle tone with a spastic or rigid walk, and failure to attain a height at maturity of more than 1 m. Today, this condition (known as endemic cretinism) is most prevalent in impoverished areas of African and East Asian countries. Prior to implementation of a national program of iodized salt in the early part of the twentieth century, endemic cretinism was commonplace in Switzerland. After institution of iodized salt, deaf-mutism declined 50% within 8 years and no cretins have been born in that country since 1930. 

Transplacental passage of maternal T4 Physiological changes in pregnancy in iodine-deficient women... 

A. Brain damage caused by maternal/fetal/neonatal iodine deficiency A. Brain damage caused by maternal hypothyroidism ... 

Iodine deficiency results in lowered maternal circulating thyroid hormone concentrations, leading to reduction in placental transfer of thyroxine. The possibility of iodine storage by the placenta compensating for diminished dietary iodine intake has been suggested by Delange (2004), and placental iodine storage has been demonstrated (Smyth et al, 2006). 

Recently, a WHO technical consultation group met to review the maternal iodine requirements during gestation (Benoist et al, 2007). Consideration was given to the fact that the amount recommended should be sufficient to prevent brain damage or thyroid function disorders due to iodine deficiency during pregnancy. There is a lack of data to indicate an optimal intake. Therefore, conclusions were reached after evaluation of the efficiency of gut absorption of iodine, the estimated metabolic needs, and the typical daily losses in the feces and urine. 

Pregnant and lactating women and neonates are the main targets of the effects of iodine deficiency, because of the impact of maternal, fetal and neonatal hypothyroxinemia on... 

Feto-Maternal Repercussions of Iodine Deficiency during Pregnancy and the Immediate Postnatal Period... 

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