Effects of smoking on fetus

Effects of Smoking on Fetus

2007

The increased incidence of smoking by women of childbearing age in recent decades has stimulated considerable research on the effects of cigarette smoking on the development of the fetus . According to the 1980 National Neonatal Survey , 31 percent of all married mothers and 47 percent of all teenage married mothers were cigarette smokers prior to becoming pregnant (Prager et al . 20 . The comparable rates among unmarried mothers is , undoubtedly , higher . Although data remain inconclusive concerning the full impact of maternal smoking , several decades of

major research studies and substantial statistical findings confirm a variety of deleterious effects of tobacco on fetal development and pregnancy outcome . Among these effects , maternal smoking during pregnancy is associated to varying degrees with retarded fetal growth resulting in low birth weight , premature birth , complications in pregnancy , heightened rates of spontaneous abortion , stillborn birth and newborn mortality

The most clearly corroborated finding to date is that mothers who smoke are at higher risk than nonsmoking mothers of giving birth to low birth weight babies . The average weight of a smoker 's baby is 200 grams less than a nonsmoker 's across all categories . One study found that women smokers over thirty-five years of age had babies weighing on average 301 grams less than nonsmokers of that age (Wen et al . 57 . Reinforcing this , a significantly greater proportion of smokers ' infants weigh less than 2 ,500 grams at birth , putting them at higher risk for a range of potential complications . One observer reports that 25 percent or more of infants born to women who smoke ten or more cigarettes per day are born with moderate to severe intrauterine growth retardation (Risemberg 150 Research also shows that the greater the number of cigarettes a woman smokes during pregnancy , the greater the chances of bearing a low birth weight baby . Moreover , actual birth weight declines steadily as the number of cigarettes smoked increases , implying a cumulative effect of smoking on the fetus

Although birth weight is determined by a complex of genetic environmental , and pregnancy-related factors , maternal smoking reduces birth weight regardless of the other factors at work . Meyer and associates concluded that of all relevant factors studied , the largest decline in birth weight was attributable to maternal smoking (465 However , Rush notes that the effect of smoking is mediated by the nutrition of the mother , and that depressed birth weights associated with smoking can be "normalized " through nutritional supplements (211 Rush surmises that the relationship between heavy smoking and poor nutrition accounts for the markedly worse effect of smoking on the poor possibly because "more affluent smokers are protecting themselves by sustaining their weight gain , presumably by maintaining dietary intake in spite of their smoking , while poorer smokers are not (211 . Although these findings are inconclusive , they further demonstrate the complexity of isolating causal relationships in fetal growth and development

Although many hypotheses have been advanced to explain why smoking causes reduced birth weight , the preponderance of evidence points to carbon monoxide...