Pathogenesis of fetal growth retardation and behavioral disorders in the progeny caused by smoking during pregnancy
Literature data on the harmful effects of smoking during pregnancy are reviewed with special emphasis on the fetal growth retardation and delayed changes in child behavior. Intrauterine growth retardation is one of the major causes of low birth weight. It was shown that the birth weight of neonates in smoking mothers can be decreased by 30-396 g. Mass screening data indicate that smoking during pregnancy also increases perinatal mortality (up to 28%). Intrauterine growth retardation was also observed following passive smoking. Inhalation of tobacco smoke by pregnant women was found to increase the fetal heart rate and inhibit fetal movements. Children born from smoking mothers had the higher incidence of asphyxia cyanosis and hyperactivity. Mass longitudinal studies of children of smoking mothers indicated learning disability slight mental retardation and insufficient social adaptation by the age of 7 years. Special neurological follow-up study of 326 children revealed frequent minimal brain dysfunction. Pathogenesis of fetal disorders was shown to be associated with impaired adaptation to pregnancy in smoking women. Majority of the constituents of tobacco smoke are capable to pass through the placental-fetal barrier. The most harmful components for fetal development were found to be nicotine and carbon monoxide which reduce the placental perfusion and blood flow. Exposure to carbon monoxide was shown to increase the level of carboxyhemoglobin and decrease the level of oxyhemoglobin resulting in reduced oxygen supply to fetal tissues and fetal anoxia.