Pregnancy iodine intakes

Sheep and cattle developed the same symptoms of iodine deficiency. Abortion rate, length of pregnancy (4 days longer) and mortality of the lambs were significantly increased (Groppel 1986, Groppel and Korber 1982, Groppel etal. 1983). Cows with an iodine intake of 70 pg kg feed DM produced 19% less milk than con-... 

Figure 28.3 Interaction between previous pregnancy, smoking and low iodine intake. The association between tobacco smoking, parity and thyroid volume in the DanThyr population study, inoluding 3712 women. A significant statistical interaction was found for tobaoco smoking on the association between parity and thyroid volume. Reproduced from Knudsen et al., (2002a) with permission.

Pregnant and lactating women are vulnerable to iodine deficiency if specialized enteral preparations are their sole source of nutrition. Only 9 out of 44 specialized enteral preparations for adults provide the current requirement of 200 pg/day. If the WHO technical consultation presently under review is accepted, then only two preparations will meet the proposed allowance of 250 pg/day. This has particular consequences for the brain development of the fetus and infant if the mother has an iodine deficiency during pregnancy and if she breast-feeds. Generally, standard infant formula are recommended for use by the manufacturers for up to 1 year, but as infants are weaned from approximately 6 months, estimation of iodine intakes can only be approximate as the mixed diet progresses. 

Table 42.2 Thyroid parameters indicating deficient iodine intake in pregnancy...

ID beoomes signifioant during pregnancy when the iodine intake falls below lOOpg/day... 

Increased Production of Thyroid Hormone in Pregnancy Depends on Adequate Dietary Iodine Intake During... 

The fetus is totally dependent on maternal iodine supply throughout gestation, and on thyroxine supply during the first trimester of pregnancy for normal neurological development and nervous system maturation. It is therefore imperative that TH synthesis is adequate and is met with the appropriate iodine intake. Accordingly, it is important to know the trimester-specific reference intervals for THs and other thyroid functions in pregnancy. 

In mild and moderate iodine deficiency, endemic cretinism is not observed. However, in a population there is a certain spread of iodine intake, and women at the lower end of the range of iodine intake may still be at risk of insufficient iodine intake during pregnancy. Deficiency of other nutrients and intake of goitrogens from food or from tobacco smoking may increase the risk. 

Insufficient iodine intake is a crucial factor that contributes to the frequency of hypothyroidism during pregnancy... 

It occurs in very specific environmental and/or physiological circumstances, namely ID and pregnancy. The coexistence of both of these conditions, i.e. pregnancy in women whose iodine intake is inadequate, results in the highest risk of gestational hypothyroxinemia in the mothers. 

Reduced Iodine Intake and Iodine Prophylaxis in Pregnancy Importance of Hypothyroxinemia in the First Trimester of Gestation... 

---