Fetus Affected by Mother's Underactive Thyroid
Researchers have discovered that a mother's hypothyroidism can adversely affect a developing fetus, even if the fetus's thyroid is normal. The study was conducted by researchers from the Foundation for Blood Research in Maine, the New England Newborn Screening Program, Boston Children's Hospital, Beth Israel Deaconess Medical Center, and Dartmouth Medical School in New Hampshire.
The thyroid is stimulated by thyrotropin, a hormone produced by the pituitary gland. For this study, three groups were formed from a pool of more than 25,000 pregnant women who'd had their thyrotropin levels taken between 1987 and 1990. The first group had extremely high levels of thyrotropin. Group 2 had high thyrotropin levels and low levels of the thyroid hormone thyroxine. Group 3 was a control group with normal levels of both hormones.
The participants' children, now ages seven to nine, were tested on intelligence, attention, language and reading abilities, school performance, and visual/motor skills.
Compared to the control group's children, group one's children didn't perform as well on any of the 15 tests given. Their IQs were about four points lower, with 15 percent scoring under 85.
The children of group two scored worse. IQs averaged seven points lower than the control group, with 19 percent scoring under 85.
During pregnancy, the mother provides thyroxine to the fetus. The fetus's thyroid begins working in the second trimester, but it doesn't depend on it until after birth. When the mother's supply is cut off at birth, a child with an underactive thyroid will suffer permanent mental retardation unless the condition is identified and treated immediately. This study is the first to link maternal thyroid deficiency to a child's mental development.
The American Medical Women's Association (AMWA ) is glad to see more attention being given to the problem of hypothyroidism, particularly for women. The organization believes that more than half of an estimated 13 million U.S. women with thyroid disease are undiagnosed. The AMWA urges routine thyroid screening for all women, especially during the childbearing years.
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