Abstract 1323 Poster Session II, Sunday, 5/2 (poster 16)

Objective: To study the effect of maternal thyroid function in the furst half of pregnancy in patients with known thyroid disease on the neurologic development of the infants in the first two years of life.

Design: Prospective observational study.

Patients & Methods: Clinical and thyroid function data were collected from pregnant women with known thyroid disease and their newborn children. Infants were divided in three groups according to their maternal thyroid function within the first half of pregnancy: Group A (n=7): maternal subclinical hypothyroidism, Group B (n=6): maternal euthyroidism, and Group C (n=7): maternal hyperthyroidism or subclinical hyperthyroidism. Neurophysiologic (Motor nerve conduction velocity (MNCV), Somatosensory evoked potentials [SEPs]), neurologic and developmental (Bayley scales) assessments were done.

Results : One infant, born to a mother with Graves' disease developed transient hyperthyroidism. The mean Mental Developmental score for infants in Group A was 14 points lower (95% CI: 2 - 26) compared to Group B (p=0.02) in the fist two years of life. Neurophysiologic and neurologic assessments and the mean Psychomotor Developmental scores did not differ among the three groups.

Conclusion : Maternal subclinical hypothyroidism in the fist half of pregnancy was associated with a lower mean Mental Developmental score in their infants during the first two years of life.