High risk of sensorineural hearing loss in men born small for gestational age with and without obesity or height catch-up growth: a prospective longitudinal register study on birth size in 245,000 Swedish conscripts.
BACKGROUND: Several components of the metabolic syndrome coincide with those risk factors linked to sensorineural hearing loss (SNHL). According to the thrifty phenotype hypothesis, the metabolic syndrome can be caused by events during the fetal period. This study tests the thrifty phenotype hypothesis on hearing, using body size at birth and conscription as indirect markers for fetal programming and body mass index as an indicator for the metabolic syndrome. METHODS: Odds ratios were used to analyze birth data regarding body size from birth to conscription as risk factors for hearing loss in 245,092 conscripted Swedish men. FINDINGS: Compared with conscripts born short for gestational age with catch-up growth, those born short with absence of catch-up growth exhibited 134% higher risk of SNHL. Adult short stature was associated with a 50% increased risk. Compared with conscripts with average body mass index, overweight was associated with 30%, obesity with 99%, and overweight if born light for gestational age with 118% higher risk of SNHL. Conscripts born light for gestational age had a 41% increased risk, independent of the later growth pattern. CONCLUSION: The thrifty phenotype hypothesis also seems to be valid for SNHL, meaning that SNHL in adulthood may originate from events during fetal life. SNHL might be a new clinical feature of the metabolic syndrome.