Premature delivery, low-birth weight, even death—smoking during pregnancy can have severe negative effects on a baby (in addition to the increased health risks to the woman smoking). The number of women who smoke during pregnancy dropped 30% during the 1990s, according to the American Lung Association. But many women continue to smoke during and after pregnancy, placing their children and themselves at great risk of health problems. A study in the November 2002 issue of the American Journal of Public Health investigated what determines women’s patterns of smoking around the time of pregnancy.

Researchers have suspected that factors such as level of education and race play a role in women's smoking habits. Previous studies have shown that well-educated women are more likely to quit smoking for good than women with less education. This study adds strength to that finding and also highlights the influence that living with a smoker can have on quitting success.

About the Study

Researchers from the Children's Hospital Medical Center in Cincinnati and the University of Washington School of Medicine in Seattle analyzed data from a two-part national study originally designed to identify factors related to poor pregnancy outcomes. The 1988 National Maternal and Infant Health Survey (NMIHS) and the 1991 Longitudinal Follow-Up (LF) asked 8285 women about specific behaviors during their pregnancies. The women filled out the NMIHS and LF surveys at 17 and 35 months after delivery, respectively.

Researchers measured four main outcomes based on the answers (yes or no) to three questions on the NMIHS survey and one question on the LF survey:

  • Did you smoke cigarettes during the 12 months before delivery?
  • Did you quit smoking for at least a week during your pregnancy?
  • Do you smoke cigarettes now? (Asked at 17 months)
  • Do you smoke cigarettes now at all? (Asked at 35 months)

On the surveys, women also reported personal information such as their education and income levels, their alcohol consumption during pregnancy, and the number of other smokers in their households. Women were divided into groups based on this information. (For example: less than 12 years of eduction, 12 years of education, some college education, and college graduate.) Researchers then compared the smoking status of women in different groups based on their personal information. The survey responses of 7969 of the women were used to calculate findings.

The Findings

Of the 2311 women who reported smoking in the 12 months before giving birth, 56% quit for at least one week during pregnancy. However, the majority (72%) of these women who had quit smoking were lighting up again by 17 months after giving birth.

Two factors—education level and other household smokers—were strongly associated with a woman smoking during and after pregnancy. Compared to women who graduated college, women who did not finish high school showed the following behaviors:

  • Four times as likely to smoke in the 12 months before giving birth
  • One-third as likely to quit during pregnancy
  • Three times as likely to restart the habit after giving birth (if they had quit during pregnancy)

Similarly, women who lived with another smoker were four times as likely to smoke during and after pregnancy and two-thirds as likely to quit during pregnancy, compared with those who did not live with another smoker.

While these findings are interesting and important, there are limitations to this study. First, data collection depended on memory. The first survey was done 17 months after giving birth, and asked women to recall their habits as far back as 12 months before they gave birth. Any survey relying on a person's memory is prone to error, and due to the social stigma associated with smoking—especially during pregnancy—women may have under-reported their actual smoking habits. Second, since the questions on smoking habits allowed only yes/no answers, we do not know if there are differences between those who smoked for 2 months and those who smoked for all 12. We also cannot tell how much these women smoked and how often. Lastly, the researchers presumably adjusted their findings to account for confounding factors that may be linked to smoking, education, and household smokers, but they did not explicitly report this in the study.

How Does This Affect You?

This study sheds light on some of the factors associated with a woman's success in quitting smoking. The authors highlight the need to integrate anti-smoking programs across health care contacts to provide women the support they need to overcome these barriers.

If you're a woman who smokes, and are pregnant or thinking of becoming pregnant, quitting and/or reducing your exposure to smoke can help protect you and your baby from an array of serious medical problems. Seek help in quitting (see the links below) and strongly encourage those you live with to quit smoking as well. Your baby’s health depends on it.