Neurodevelopment in children born to hypothyroid mothers restored to normal thyroxine (T₄) concentration by late pregnancy in Japan: no apparent influence of maternal T₄ deficiency.
BACKGROUND
The importance of maternal T₄ for brain development prior to the onset of fetal thyroid function has been suggested in basic studies, and a correlation between mild maternal T₄ deficiency in early gestation and disturbance of neurodevelopment in progenies has been shown in large case-control studies. These findings suggest that maternal T₄ deficiency in early pregnancy potentially affects neurointellectual development. On the other hand, no apparent adverse effect in children born to mothers with overt hypothyroidism in Japan has been reported where maternal T₄ had been restored to normal by late pregnancy.


OBJECTIVE
We report five cases in Japan showing no apparent effect of maternal T₄ deficiency on neurodevelopment in progenies where low T₄ levels had been corrected by late pregnancy.


METHODS
Five women with overt hypothyroidism detected at 6-16 wk gestation initiated T₄ treatment. Four women restored euthyroidism by the 20th week. One remained in a subclinical hypothyroid state. Developmental scores of their children were evaluated between 25 months and 11 yr of age by either the Tsumori-Inage Infant's Developmental Test or the Wechsler Intelligence Scale for Children-Third Edition and compared to those of corresponding siblings with no exposure to maternal hypothyroidism.


RESULTS
The development scores of all the children turned out to be either normal or advanced.


CONCLUSIONS
In iodine-sufficient areas, maternal T₄ deficiency in early pregnancy does not necessarily affect neurodevelopment. Therefore, other potential factors altering neurodevelopment, such as iodine deficiency, must be investigated.
Tokyo Health Service Association (N.M., S.I.), Tokyo 162-8402, Japan. momotani@blue.ocn.ne.jp
Naoko
N
Momotani
Saika
S
Iwama
Ko
K
Momotani
D000293:Adolescent; D002648:Child; D002657:Child Development / Q000187:drug effects; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000139:chemically induced / Q000209:etiology / Q000517:prevention & control; D005260:Female; D047109:Fetal Development / Q000187:drug effects; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy* / Q000208:ethnology / Q000503:physiopathology; D007361:Intelligence Tests; D007564:Japan; D008297:Male; D055495:Neurogenesis / Q000187:drug effects; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000188:drug therapy* / Q000208:ethnology / Q000503:physiopathology; D011297:Prenatal Exposure Delayed Effects / Q000517:prevention & control; D013974:Thyroxine / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*
D013974:Thyroxine