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Smoking and Pregnancy: What Are the Risks?
In pregnant women, carbon monoxide (a lethal gas) and the high doses of nicotine obtained when they inhale tobacco smoke interferes with oxygen supply to the fetus. Nicotine readily crosses the placenta, and nicotine concentrations in the fetus can be as much as 15 percent higher than maternal levels. It appears that nicotine is concentrated in fetal blood, amniotic fluid, and breast milk. Another ingredient of tobacco smoke, carbon monoxide, has been shown to inhibit the release of oxygen into fetal tissues. These factors, combined, likely account for the developmental delays commonly seen in the fetuses and infants of smoking mothers.
Women who smoke during pregnancy are at greater risk than nonsmokers for premature delivery, and there is a risk of lower birth weight for infants carried to term. In the United States it is estimated that 20 percent or more of pregnant women smoke throughout their pregnancies. The adverse effects of smoking may occur in every trimester of pregnancy; they range from spontaneous abortions in the first trimester to increased premature delivery rates and decreased birth weights in the final trimester. The decreased birth weights seen in infants of mothers who smoke reflects a dose-dependent relationship: the more the woman smokes during pregnancy, the greater the reduction of infant birth weight. Conversely, women who give up smoking early in pregnancy have infants of similar weight to those of nonsmokers.
Are there effective treatments for nicotine addiction?
Extensive research has shown that behavioral and pharmacological treatments for nicotine addiction do work. For those individuals motivated to quit smoking, a combination of behavioral and pharmacological treatments can increase the success rate approximately twofold over placebo treatments. Furthermore, smoking cessation can have an immediate positive impact on an individual's health; for example, a 35-year-old man who quits smoking will, on the average, increase his life expectancy by 5.1 years.
Nicotine Replacement Treatments
Nicotine was the first pharmacological agent approved by the Food and Drug Administration (FDA) for use in smoking cessation therapy. Nicotine replacement therapies, such as nicotine gum, the transdermal patch, nasal spray, and inhaler, have been approved for use in the United States. They are used to relieve withdrawal symptoms, because they produce less severe physiological alterations than tobacco-based systems, and generally provide users with lower overall nicotine levels than they receive with tobacco. An added benefit is that these forms of nicotine have little abuse potential since they do not produce the pleasurable effects of tobacco products. Nor do they contain the carcinogens and gases associated with tobacco smoke.
The FDA's approval of nicotine gum in 1984 marked the availability (by prescription) of the first nicotine replacement therapy on the U.S. market. In 1996, the FDA approved gum (NicoretteŽ) for over-the-counter sales. Whereas nicotine gum provides some smokers with the desired control over dose and ability to relieve cravings, others are unable to tolerate the taste and chewing demands. In 1991-1992, FDA approved four transdermal nicotine patches, two of which became over-the-counter products in 1996, thus meeting the needs of many additional tobacco users.
Since the introduction of nicotine gum and the transdermal patch, estimates based on FDA and pharmaceutical industry data indicate that more than 1 million individuals have been successfully treated for nicotine addiction. In 1996 a nicotine nasal spray, and in 1998 a nicotine inhaler, became available by prescription. All the nicotine replacement products- gum, patch, spray and inhaler- appear to be equally effective. In fact, the over-the-counter availability of many of these medications, combined with increased messages to quit smoking in the media, has produced about a 20 percent increase in successful quitting each year.
Non-Nicotine Therapies
Although the major focus of pharmacological treatments of nicotine addiction has been nicotine replacement, other treatments are being developed for relief of nicotine withdrawal symptoms. For example, the first non-nicotine prescription drug, bupropion, an antidepressant marketed as ZybanŽ, has been approved for use as a pharmacological treatment for nicotine addiction. In December 1996, a Federal advisory committee recommended that the FDA approve bupropion to become the first drug to help people quit smoking that could be taken in pill form, and the first to contain no nicotine.
Behavioral Treatments
Behavioral interventions can play an integral role in nicotine addiction treatment. Over the past decade, this approach has spread from primarily clinic-based, formal smoking-cessation programs to application in numerous community and public health settings, and now to telephone and written formats as well. In general, behavioral methods are employed to (a) discover high-risk relapse situations, (b) create an aversion to smoking, (c) develop self-monitoring of smoking behavior, and (d) establish competing coping responses.
Other key factors in successful treatment include avoiding smokers and smoking environments and receiving support from family and friends. The single most important factor, however, may be the learning and use of coping skills for both short- and long-term prevention of relapse. Smokers must not only learn behavioral and cognitive tools for relapse prevention but must also be ready to apply those skills in a crisis.
Although behavioral and pharmacological treatments can be extremely successful when employed alone, science has taught us that integrating both types of treatments will ultimately be the most effective approach. More than 90 percent of the people who try to quit smoking relapse or return to smoking within 1 year, with the majority relapsing within a week. There are, however, an estimated 2.5 to 5 percent who do in fact succeed on their own. It has been shown that pharmacological treatments can double the odds of their success. However, a combination of pharmacological and behavioral treatments further improves their chances. For example, when use of the nicotine patch is combined with a behavioral approach, such as group therapy or social support networks, the efficacy of treatment is significantly enhanced.
Are there gender differences in tobacco smoking?
Several avenues of research now indicate that men and women differ in their smoking behavior and that differences in nicotine sensitivity may be the root cause. Studies of smoking behavior seem to indicate that women smoke fewer cigarettes per day, tend to use cigarettes with lower nicotine content, and do not inhale as deeply as men. Whether this is because of differences in sensitivity to nicotine is an important research question. Some researchers are finding that women may be more affected by factors other than nicotine, such as the sensory aspects of the smoke or social factors, than they are by nicotine itself.
The number of smokers in the United States declined in the 1970s and 1980s, but has been relatively stable throughout the 1990s. Because this decline of smoking was greater among men than women, the prevalence of smoking is only slightly higher for men today than it is for women. Several factors appear to be contributing to this trend, including increased initiation of smoking among female teens and, more critically, women being less likely than men to quit smoking.
Large-scale smoking-cessation trials show that women are less likely to initiate quitting and may be more likely to relapse if they do quit. In cessation programs using nicotine replacement methods, such as the patch or gum, the nicotine does not seem to reduce craving as effectively for women as for men. Other factors that may contribute to women's difficulty with quitting are that the withdrawal syndrome may be more intense for women and that they appear more likely than men to gain weight upon quitting. It is important for women entering smoking cessation programs to be aware that standard treatment regimens may have to be adjusted to compensate for gender differences in nicotine sensitivity.
Source: National Institute on Drug Abuse