Preliminary screening may not benefit unborn children of hypothyroid mothers

Preliminary results of the Controlled Antenatal Thyroid Screening (CATS) study did not show a benefit of screening for hypothyroidism during pregnancy on the intellectual development of children.

Endocrine Today reports that the CATS study sought to answer whether screening for thyroid function in early gestation with levothyroxine intervention would improve the intelligence of pregnant women's children.

The trial compared more than 22,000 pregnancies at less than 16 weeks gestation. The primary outcome was the child's IQ at age 3.2 years and at age 3.6 years and the percentage of children with an IQ of less than 85, using the WPPSI-III child intelligence assessment score.

The study was conducted at two sites, in Cardiff and Turin, Italy. The researchers noted some discrepancies between the groups at baseline, including heavier women and a higher prevalence of smokers in Cardiff and older mothers in Turin.

According to the main results of the intent-to-treat analysis, child intelligence scores were similar in the screening and control groups. The average IQ score was 99.3 in the screening group versus 100 in the control group. More than 15 percent of children in the control group had an IQ of less than 85 versus 11.5 percent in the screening group.

According to the Centers for Disease Control, when pregnant women experience hypothyroidism, all of their bodily functions slow down and there can be problems with the baby's development.