Neurodevelopment
may be delayed in infants of mothers with low serum free thyroxine
values in early pregnancy
(November 2003)
The background of the study. The
neurodevelopment of infants of mothers with overt hypothyroidism
is impaired. This study assessed the neurodevelopment of infants
whose mothers had low serum free thyroxine (T4) concentrations,
but not hypothyroidism, during early pregnancy.
How the study was done. The study
began with enrollment of healthy women at 12 weeks' gestation who
had a serum free T4 concentration in the lowest 10th percentile
or the 50th to 90th percentile. The study subjects were 63 one-year-old
and 57 two-year-old infants in the low serum free T4 group and 62
one-year-old and 58 two-year-old infants in the higher serum free
T4 group. Infant development was assessed using the Bayley Scales
of Infant Development, which includes a Mental Scale (coordination,
language development) and a Psychomotor Scale (motor development).
The results of the study. At age
one year, 19 infants had delayed mental function (defined as a score
<84), 15 of whom (79 percent) were in the low serum free T4 group;
the respective numbers at two years of age were 11 and 8 (73 percent).
At one year of age, 21 infants had delayed motor function, 16 (76
percent) of these were in the low serum free T4 group; the respective
numbers at two years of age were 22 and 17 (77 percent).
The conclusions of the study. Neurodevelopmental
delay can occur in infants whose mothers have low serum free T4
concentrations early in gestation.
The original article. Pop VJ, Brouwers
EP, Vader HL, Vulsma T, van Baar AL, de Vijlder JJ. Maternal hypothyroxinaemia
during early pregnancy and subsequent child development: a 3-year
follow-up study. Clin Endocrinol 2003;59:282-8.
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