Sinistrality - a side-effect of prenatal sonography: A comparative study of young men

Although ultrasound during pregnancy is used extensively, there is little p ublished on adverse fetal effects. We undertook a cohort study including me n born in Sweden from 1973 to 1978 who enrolled for military service. We es timated relative risks for being born left-handed according to ultrasound e xposure in fetal life using logistic regression analysis. Eligible for the study were 6,858 men born at a hospital that included ultrasound scanning i n standard antenatal care (exposed) and 172,537 men born in hospitals witho ut ultrasound scanning programs (unexposed). During the introduction phase (1973 to 1975) there was no difference in left-handedness between ultrasoun d exposed and unexposed (odds ratio = 1.03, 95% confidence interval (Cl) = 0.91 to 1.17). When ultrasonography was offered more widely (1976 to 1978), the risk of left-handedness was higher among those exposed to ultrasound c ompared with those unexposed (odds ratio = 1.32, 95% CI = 1.16 to 1.51). We conclude that ultrasound exposure in fetal life increases the risk of left -handedness in men, suggesting that prenatal ultrasound affects the fetal b rain.