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- Haddow JE, Palomaki GE, Allan WC, Williams JR, Knight GJ, Gagnon
J, O'Heir CE, Mitchell ML, Hermos RJ, Waisbren SE, Faix JD, Klein
RZ
- N Engl J Med 1999 Aug 19 341:8 549-55
- Abstract
- BACKGROUND: When thyroid deficiency occurs simultaneously in
a pregnant woman and her fetus, the child's neuropsychological
development is adversely affected. Whether developmental problems
occur when only the mother has hypothyroidism during pregnancy
is not known. METHODS: In 1996 and 1997, we measured thyrotropin
in stored serum samples collected from 25,216 pregnant women between
January 1987 and March 1990. We then located 47 women with serum
thyrotropin concentrations at or above the 99.7th percentile of
the values for all the pregnant women, 15 women with values between
the 98th and 99.6th percentiles, inclusive, in combination with
low thyroxine levels, and 124 matched women with normal values.
Their seven-to-nine-year-old children, none of whom had hypothyroidism
as newborns, underwent 15 tests relating to intelligence, attention,
language, reading ability, school performance, and visual-motor
performance. RESULTS: The children of the 62 women with high serum
thyrotropin concentrations performed slightly less well on all
15 tests. Their full-scale IQ scores on the Wechsler Intelligence
Scale for Children, third edition, averaged 4 points lower than
those of the children of the 124 matched control women (P= 0.06);
15 percent had scores of 85 or less, as compared with 5 percent
of the matched control children. Of the 62 women with thyroid
deficiency, 48 were not treated for the condition during the pregnancy
under study. The full-scale IQ scores of their children averaged
7 points lower than those of the 124 matched control children
(P=0.005); 19 percent had scores of 85 or less. Eleven years after
the pregnancy under study, 64 percent of the untreated women and
4 percent of the matched control women had confirmed hypothyroidism.
CONCLUSIONS: Undiagnosed hypothyroidism in pregnant women may
adversely affect their fetuses; therefore, screening for thyroid
deficiency during pregnancy may be warranted.
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- Author Address
- Foundation for Blood Research, Scarborough, ME 04074, USA.
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