Effect of Maternal Diabetes Mellitus on Neonatal Hearing.

INTRODUCTION: Gestational diabetes is a potential risk factor for neonatal hearing loss. Increased circulating sugars in mothers during pregnancy can impairs the micro circulation and can cause congenital anomalies of the inner ear resulting in congenital hearing loss. This study attempts to find the incidence of neonatal hearing loss among diabetic mothers.

METHODOLOGY: This was a case control study with 86 neonates of diabetic mothers as cases and neonates of non diabetic mothers(n = 86) as controls. Antenatal diabetic history and sugar values of mothers were documented. Hearing status of the neonates were tested using DPOAE test and ABR test. DPOAE test was done on 3rd day and those who did not get a positive response underwent 2nd DPOAE and also ABR test if 2nd DPOAE was negative.

RESULTS: All neonates underwent DPOAE test and few were lost on follow up. First and second DPOAE showed a statistically significant difference between cases and controls. All babies who underwent ABR test had abnormal waveforms. 98% of cases showed moderate and severe bilateral hearing loss whereas all controls had only mild bilateral hearing loss.

DISCUSSION: This study showed a significantly higher percentage of abnormal hearing outcome among neonates of diabetic mothers than non diabetic mothers. This could be because of the toxic effects of maternal hyperglycemia on developing auditory system of the fetus. This study emphasis the need for better glycaemic control in diabetic pregnancy, the importance of early and mandatory hearing screening in newborns of diabetic mothers.