Hearing outcome in infants following correction of maternal hypothyroidism during pregnancy

Abstract

Purpose: There is significant prevalence of overt and subclinical hypothyroidism in pregnant women in rural areas. Maternal hypothyroidism is known to cause congenital hypothyroidism resulting in sensorineural hearing loss. Anti-Thyroperoxidase antibodies are known to cross placental barrier. There is no literature on hearing assessment in infants born to women whose hypothyroidism was corrected during pregnancy. Do these infants suffer hearing loss? Our study addresses this question.

Methods: 140 infants born to women on treatment for hypothyroidism during pregnancy and 140 infants born to euthyroid women were evaluated for hearing by Brainstem Evoked Response Audiometrry at 1 and 4 months age. Anti-TPO antibodies were estimated at 4 months of age.

Results: There was no clinical hearing deficit or delay in neurological development in infants born to women undergoing treatment for hypothyroidism during pregnancy. However wave V latency on BERA was slightly prolonged in them compared to infants born to euthyroid women. There was absence of wave V when maternal subclinical hypothyroidism persisted till parturition. However within 6-8months of age the wave V latencies corrected to normal. Anti-TPO antibodies were within normal range at 4months age.

Conclusion: Maternal hypothyroidism when corrected before parturition does not affect hearing in the infants clinically. The mild delay in wave V on BERA corrects within first year of life. However larger studies to assess hearing in infants born to women having overt hypothyroidism during first trimester of pregnancy may be desirable to assess whether hearing is adversely affected in them.

Keywords: Brainstem evoked response audiometry; Maternal hypothyroidism; Sensorineural hearing loss; Subclinical hypothyroidism.