Babies Born to Hypothyroid Mothers Have Lower I.Q.'s

Babies Born to Mothers with Untreated Hypothyroidism Have Lower I.Q.'s
Routine Thyroid Screening Should Occur During Pregnancy
August 19, 1999 -- Today's New England Journal of Medicine (NEJM) is reporting on the results of a new research study that found that untreated hypothyroidism during pregnancy may affect a child's psychological development, and result in substantially lower I.Q. levels, reduced motor skills, and problems with attention, language and reading.

The study found that women with untreated underactive thyroids during pregnancy are nearly four times more likely to have children with lower I.Q. scores. The researchers indicated that approximately 1 out of every 50 women have hypothyroidism (underactive thyroid) during pregnancy, however other experts believe this number may actually be far larger, and that a larger percentage of the population is undiagnosed or undertreated.

The study showed that 19 percent of the children born to mothers with thyroid deficiency had IQ scores of 85 or lower. This was compared to a reduced IQ level of only 5 percent of those born to mothers without such thyroid problems. According to James E. Haddow, MD, lead study author, Vice President and Medical Director for the Foundation for Blood Research, the range below 85 I.Q. level can mean significant impairment for children.

"The children whose scores are in this range may face life-long developmental challenges. It might be possible to prevent these problems through the early diagnosis and treatment of thyroid disease in their mothers."

The study found that the 62 children whose mothers were hypothyroid during pregnancy performed less well on all the various intelligence and IQ tests used for measurement. The children of the 48 women who were not treated for thyroid disease during the pregnancy had an average I.Q. score that was 7 points lower than the children in the control group, with 19 percent scoring 85 or less.