Gestational diabetes mellitus (GDM) is an increasingly frequent condition in the world causing significant morbidity and mortality. GDM is a metabolic disease that develops in pregnancy, and may result in complications in the pregnant women, similar to other patients with diabetes. The prevalence of GDM varies in relation with the population and the diagnostic criteria. Diabetes affects 6-9% of pregnant women; 99% of the cases have GDM, and diabetes is diagnosed before pregnancy in the remaining 1% [(pre-gestational diabetes mellitus (pre-GDM)]. Hearing loss is one of the most common birth defect in newborns. The incidence of congenital hearing impairment is 2-3 per 1000 births. Early diagnosis and treatment is very important for the development of auditory pathways and protection of cognitive functions. Therefore, newborn hearing screening programs have been in use in a number of countries. Transient evoked otoacoustic emissions (TEOAE) and auditory brainstem response (ABR) have been identified as basic convenient and applicable tools for neonatal screening of hearing.~Suboptimal glycemic control during pregnancy has adverse fetal effects. Congenital malformations, preterm birth and neonatal respiratory distress in the newborn are more common, at varying rates, pre-GDM and GDM. Compared to the normal population, the risk of congenital malformations is 1.9-10 fold higher in presence of pre-GDM, and 1.1-1.3 fold higher in presence of GDM. Despite our awareness on these important complications, the effect of intrauterine hyperglycemia on hearing of the newborn has not yet been studied in detail. Diabetes mellitus (DM) often causes hearing impairment, however little is known whether GDM is an antenatal risk factor for cochlear damage and hearing loss.
In this study, the investigators have aimed to investigate whether GDM is a risk factor for hearing impairment in newborns. To the investigators knowledge, this study is the first prospective, controlled study on this subject.