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Nicotine and the increased cholinergic activity it causes have been shown to impede apoptosis, which is one of the methods by which the body destroys unwanted cells (programmed cell death). Since apoptosis helps to remove mutated or damaged cells that may eventually become cancerous, the inhibitory actions of nicotine may create a more favourable environment for cancer to develop, though this remains to be proven.

Also women who use nicotine gum and patches during the early stages of pregnancy face an increased risk of having babies with birth defects, according to a study of around 77,000 pregnant women in Denmark. The study found that women who use nicotine-replacement therapy in the first 12 weeks of pregnancy have a 60 percent greater risk of having babies with birth defects, compared to women who are non-smokers.

Nicotine is a very powerful constrictor and decreases the flow of blood to the periphery of the body. It has been measured and found that there is a 29 percent blood-flow decrease to the thumb after smoking two cigarettes.