Thyroid Problems in Mother Affect Newborn
By Anthony J. Brown, MD
NEW YORK (Reuters Health) – There is an increased risk of
neurological development problems in infants born to mothers
who had low levels of thyroid hormone early in pregnancy,
according to a report in the medical journal Pediatrics.
The results indicate that low thyroid hormone levels in the
mother, even if they don’t cause any symptoms, can have
important neurological development consequences in the newborn,
lead author Dr. Libbe Kooistra, from the University of Calgary
in Alberta, Canada, told Reuters Health. The question now is
whether the magnitude of these problems warrants implementation
of maternal thyroid screening programs, he added.
In previous studies, Kooistra’s team had shown that low
levels of thyroid hormone during early pregnancy affect
neurological development in children who were several months of
age. Critics, however, had suggested that by that age, other
factors may have contributed to the problems, he said. This led
Kooistra’s group to look at the effects in newborns, since many
of the potentially contributing factors would not yet be
present.
In the new study, the Neonatal Behavioral Assessment Scale
(NBAS) was conducted on 108 infants born to mothers who had low
thyroid hormone levels at 12 weeks’ pregnancy and in a
comparison group of 96 infants. Maternal thyroid function was
also evaluated at 24 and 32 weeks’ pregnancy.
Infants of mothers with low thyroid hormone levels scored
significantly lower on certain parts of the NBAS than did
infants born to mothers with normal levels. However, only
thyroid hormone levels at 12 weeks’ pregnancy correlated with
NBAS scores; maternal thyroid function later in pregnancy
seemed to have no effect on infant outcomes.
Kooistra noted that the merits of routine thyroid screening
in pregnant women are now being debated. Coupled with past
research linking low thyroid hormone levels with obstetric
complications and hyperactivity in the child, the current
findings suggest that thyroid screening may be worthwhile, he
added.
SOURCE: Pediatrics, January 2006.