We are aware that many of you are anxious about the effects of congenital Hypothyroidism and the possible ways of treatment. That is why we brought you the results of the following study that we hope will shed some more light on congenital hypothyroidism and IQ levels in children.
In a study that was published on February 9, 2012 researchers examined the effect of treatment with levothyroxine during pregnancy for women detected by them as suffering from hypothyroidism.
There was no difference found in the IQ level among children whose mothers were treated for low thyroid levels, and children whose mothers were not treated.
The fetus starts the Secretion of thyroid hormone only 18-20 weeks into pregnancy. According to studies conducted with animals, up to this point the fetus depends on the thyroxin (T4) in maternal blood for growth and development, including maturation of the central nervous system. Iodine is essential for T4 production, and in populations where there is iodine deficiency researchers could identify cognitive improvement in children that where administered iodine supplementation before pregnancy.
A significant degree of association was established between high TSH level in pregnant women and impairment in cognitive development of the newborn. Therefore it has been suggested that screening for thyroid function in pregnant women may be justified.
The study included 21,846 participating from 10 medical centers in the UK and Italy. 10,924 women were randomly assigned to a group screening. During the pregnancy (before 15 weeks gestation) the women undergone testing of TSH levels and T4, and a positive result (corresponding to – underactive thyroid function) were defined as TSH level above the 97.5 percentile or T4 level below the 2.5 percentile (or both). Women that were found in the survey positive to – underactive thyroid function were treated with levothyroxine during pregnancy.
10,922 women were randomly entered to the control group. This group also took blood samples for detecting the level of TSH and T4, but these samples were kept frozen and tested just after birth, and the women received no thyroid treatment during pregnancy.
The children of participants with an under active thyroid underwent an IQ test at the age of 3, according to “Wechsler Pre -school and Primary Scale of Intelligence”. The test was performed – by psychologists who were unaware of the group to which the mother was assigned to.
Underactive thyroid gland condition was found in 4.6 % of women in the screening group and in 5.0 % of women in the control group. The time median when levothyroxine treatment was given was 13 weeks and 3 days pregnant. IQ testing was given to 78.2% of children their mother suffered from underactive thyroid function of the thyroid gland in the survey group and to 73.3% of those children whose mothers where in the control group .
No significant difference in the IQ level was found in children whose mothers were diagnosed by researchers as suffering from underactive thyroid function during pregnancy in the survey, with regards to the children of these mothers in the control group. Level of the average IQ of the children in the control group was defined as -100.0. Level of the average IQ of children in the survey was 99.2 (P = 0.40). In addition, no significant difference was found in the number of children that their IQ was below 85 points in each group.
The authors conclude that the results support current guidelines that do not recommend a screening test for hypothyroidism during pregnancy, since it does not indicate the effect of a treatment for hypothyroidism in the 12-13 weeks of pregnancy.