Frequently Asked Questions about Maternal Smoking During Pregnancy

How many mothers smoke during pregnancy?

Twenty-seven percent of women are smokers during their childbearing years (CDC-MMWR, 11/4/1994).

How many mothers who smoke are able to quit during their pregnancy?

In the National Health Interview Survey done in 1990, only 27% of the women quit immediately after being told that they were pregnant and an additional 12% quit by the third trimester.

What about the cigarette smoke harms the developing fetus?

Tobacco smoke has over 3,800 products in it with carbon monoxide and nicotine being the two largest components of the smoke. Cigarette smoke may harm a fetus by reducing blood flow or flow of oxygen to the fetus, by reducing the nutrients that reach the fetus, and by direct action to the fetus.

Does maternal smoking during pregnancy result in small babies?

The most consistent finding associated with maternal smoking during pregnancy is lower birthweight. Most studies find a difference of 200-250 grams between babies of mothers who smoke and those who do not. In addition, the incidence of intrauterine growth retardation has been found to be higher among women who smoked during their pregnancy.

Does maternal smoking during pregnancy result in premature babies?

The length of the pregnancy has been found to be lower among women who smoked during the pregnancy but the average decrease is typically only 1-2 days. Studies assessing the incidence of prematurity have found mixed results with some finding a significant increase and others not.

Does prenatal exposure to tobacco smoke cause sudden infant death syndrome (SID)?

Studies examining the incidence of SIDS among women who smoke during the pregnancy have also been mixed with some finding significant effects and other not. Parental smoking during early development has also been linked to an increased incidence of SIDS as a result of environmental tobacco smoke on a young respiratory system.

Does maternal smoking during pregnancy cause birth defects?

A few studies have been suggestive of birth defects. One study found a 17-fold increase in the incidence of anencephaly associated with maternal smoking and another found an increased incidence of congenital heart disease. However, there have been no consistent findings of a pattern of birth defects associated with maternal smoking and additional studies are needed controlling for other important factors that may impact on fetal development.

What are the long-term effects on the growth of children of being exposed to tobacco smoke during pregnancy?

The results from the British National Child Development Study on children’s growth and development suggested that children of women who smoked during their pregnancy continued to be shorter (an average of 1.0 cm) than children of women who did not smoke during their pregnancy at 7 and 11 years of age. These results were found after controlling for important other causal variables, such as mother’s height, age, social class, number of other children in the household, and the sex of the child.

What are other long-term effects of tobacco smoke exposure?

The respiratory system of children whose mothers smoke may be impaired. Children of women who smoke at least 10 cigarettes a day have a higher incidence of asthma than children of women who do not smoke. Postnatal exposure to tobacco smoke has also been linked to increased incidence and increased severity of asthma symptoms.

What are the long-term effects on the neurodevelopment of children being exposed to tobacco smoke during pregnancy?

Evidence for a general learning deficit being associated with maternal smoking has been inconsistent with some studies finding small differences and others finding no differences at all. More consistently, children of smokers have been found poor auditory processing skills. Studies have identified this deficit in newborns and in children as old as 12 years of age after controlling for other potential causal variables. Deficits in this area may interfere with a child’s learning to speak and later in learning to read. Finally, some studies suggest that children of women who smoke may have poorer attentional regulation skills, more conduct problems, and an increased probability of being diagnosed with Attention Deficit-Disorder.

Does maternal passive exposure to environmental tobacco smoke (ETS) harm the fetus?

Prenatal and postnatal tobacco smoke tend to be related making it difficult to assess the relative contributions of the different methods of exposure. The available evidence suggests that ETS can contribute to similar effects associated with active maternal smoking. However, the size of the effects tends to be smaller.

For additional information on tobacco smoke use:

Does Maternal Smoking Affect Infant Language?

Although most women who abuse alcohol and other drugs also smoke cigarettes, the effect of prenatal exposure to tobacco is not well explored. The negative effects of smoking on birth weight were known and women in the 1960's were warned not to smoke when pregnant to avoid having a low birth weight baby. However, we were also told that the baby's weight would quickly "catch up" following birth and that there were no other negative consequences. Over time, some other problems were identified particularly in children who lived with smokers and were exposed to what is called ETS (environmental tobacco smoke).


Facts About Smoking During Pregnancy

Smoking Cessation

Maternal Smoking During Pregnancy Associated with Negative Toddler Behavior and Early Smoking Experimentation

January 2004 (Volume 4)

Smoking Tobacco in Pregnancy and Later Outcomes

November 2000 (Volume 1)

Substance Abuse and Treatment