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The Developmental Effects of Nicotine on Chick Embryos

Aaron Elliott and T.J. Unger

More than 22 million American women smoke and approximately 25% of these women continue to smoke during pregnancy (Lambers and Clark 1996). Cigarette smoke has long been associated with increased health risks to the unborn baby. It contains thousands of different chemicals that could be harmful to various processes of development. One of the most hazardous chemicals in cigarettes is nicotine. Nicotine, the chief alkaloid in tobacco, is known to have adverse effects on body development. Nicotine exposure is known to cause premature birth, growth restriction, premature rupture of membranes, preterm labor, spontaneous abortion, and an increase in heart rate (Lambers and Clark 1996). Nicotine is also known to impair the absorption of calcium, vitamin C and other vitamins and minerals required by a developing fetus (Nash and Persaud 1989). Despite these known risks many pregnant women continue to smoke, exposing the unborn baby to nicotine.

When smokers breath in smoke they draw nicotine into their lungs. The nicotine is then able to enter the bloodstream and other parts of the body. If a woman is pregnant, the nicotine is able to reach the fetus by crossing the placenta and circulating into the baby's blood. Due to the reduction of oxygen and nutrients supplying the fetal tissues, the effects of nicotine can be seen in every trimester from spontaneous abortions in the first trimester to premature delivery, malformations and decreased birth weight in the third (Blair et al. 1996). Although the effects of nicotine are not the same for every organism, most exhibit some retardation of embryonic growth when exposed.

©Cebra-Thomas, 2000

Last Modified: 5 May 2000

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