The Effects of Tobacco Use During and After Pregnancy on Exposed Children

Alcohol Research & Health, Winter, 2000 by Marie D. Cornelius

DAY, NANCY L.

Relevance of Findings for Alcohol Research

Alcohol and tobacco use during pregnancy have both been associated with a number of adverse effects on the growth, cognitive development, and behavior of the exposed child. Understanding the effects of prenatal tobacco exposure allows researchers to identify those characteristics that are uniquely related to tobacco and those that are affected by alcohol exposure. This research, along with studies on the effects of alcohol use during pregnancy, has implications for preventing various types of substance use during pregnancy and for treating children affected by prenatal substance use. KEY WORDs: tobacco in any form; smoking; pregnancy; adverse drug effect; postnatal AOD (alcohol or other drug) exposure; prenatal AOD exposure; infant; cognitive development; psychobehavioral AODE (effects of AOD use, abuse, and dependence); growth and development

Women who smoke during pregnancy are also likely to drink alcohol. In one survey, conducted as part of the Maternal Health Practices and Child Development (MHPCD) project in Pittsburgh, Pennsylvania, 76 percent of adult women who reported smoking during their first trimester of pregnancy said that they also drank alcohol during that period (Day et al. 1992). Among pregnant teenagers surveyed, 61 percent of those who smoked during the first trimester also drank alcohol (Cornelius et al. 1995). In addition, tobacco and alcohol use are both prevalent among women who use illicit drugs during pregnancy. In the National Pregnancy and Health Survey (National Institute on Drug Abuse [NIDA] 1996), 74 percent of women who used illicit drugs during pregnancy also reported either smoking, drinking, or both. The use of either one of these drugs is, in itself, a risk factor for poorer pregnancy outcome.

Although alcohol and tobacco are frequently used together during pregnancy, researchers studying the negative effects of prenatal exposure to tobacco and alcohol have generally examined the effects of each drug separately. Therefore, it is difficult to discuss the effects of the combined use of the two drugs. Although the other articles in this issue examine the use of alcohol and tobacco together, this article focuses on tobacco use during pregnancy and the effects of prenatal tobacco exposure. Understanding the effects of prenatal tobacco exposure allows the identification of those characteristics that are uniquely related to tobacco and those that are affected by alcohol exposure. This research, along with research on the effects of alcohol use during pregnancy, has implications for preventing various types of substance use during pregnancy and for treating children affected by prenatal substance use.

Prenatal tobacco exposure has been reported to be a significant risk factor for sudden infant death syndrome (SIDS) (National Cancer Institute [NCI] 1999) and is estimated to be responsible for up to 4,800 infant deaths as well as 61,000 low-birth-weight (LBW) infants and 26,000 infants requiring neonatal intensive care annually (DiFranza and Lew 1995). In a national survey of pregnant adult women, however, 20.4 percent reported smoking cigarettes during pregnancy (NIDA 1996). This proportion rises to about one-half for women in lower socioeconomic populations (Cornelius et al. 1995; Day et al. 1992).

Smoking during pregnancy is more prevalent among Caucasian women compared with African-American or Hispanic women (NIDA 1996). Caucasian women also smoke at higher levels than do women of other ethnicities. Women who smoke during pregnancy are less likely to be married, have less education, have lower incomes, and attend fewer prenatal visits compared with women who do not smoke during pregnancy (Day et al. 1992; Cornelius et al. 1994).

Compared with alcohol, marijuana, and other illicit drug use, tobacco use is less likely to decline as the pregnancy progresses (Day et al. 2000; Cornelius et al. 1995). In the National Pregnancy and Health Study (NIDA 1996), approximately two-thirds of the women who smoked prior to their pregnancy continued smoking into the last trimester. In contrast, only one-fourth of the women who used alcohol prior to conception continued to drink into the third trimester. Women who smoke during pregnancy also continue smoking after the pregnancy (Cornelius et al. 1999a; Leech et al. 1999). Therefore, children born to women who use tobacco during pregnancy are likely to continue to be exposed to tobacco after birth. This environmental, or passive, exposure may also affect the children's development.

EFFECTS OF SMOKING DURING PREGNANCY

This section of the article reviews findings on the effects of maternal smoking during pregnancy on the exposed children's growth, cognitive function, and behavior. The subsequent section focuses on the effects of passive smoking. Because of space limitations, this article does not review research on the effects of prenatal alcohol exposure. Because women who smoke during pregnancy are also likely to drink alcohol and use other drugs, many of the studies reviewed here controlled for prenatal alcohol exposure and other confounding factors, to determine the unique effects associated with prenatal tobacco exposure.