Tuesday, May 18, 2010

Tobacco Harm Reduction: Not During Pregnancy

One of the most common – and challenging – questions regarding tobacco harm reduction is whether it is applicable to pregnant women who smoke.

According to the 2004 Surgeon General’s report, smoking during pregnancy is associated with increased risks for premature delivery, low-birth-weight infants, and stillbirth. Smoking is also associated with increased risk for problems with the placenta (the organ that nourishes the fetus). These problems include growth of the placenta in the wrong location (placenta previa) and separation of the placenta from the mother’s uterus (placental abruption), both of which can place the mother and developing fetus at risk. Paradoxically, pregnant women who smoke have a significantly lower risk of preeclampsia (a form of high blood pressure). But the overall effect of smoking on the developing fetus is decidedly negative.

Can a pregnant smoker who switches to smokeless tobacco benefit her health and that of her developing baby? Only one scientific study has addressed this issue. It reported information on pregnancy outcomes among Swedish women who used snus or smoked, compared with nonusers of tobacco, and it was published in 2003 by a group of investigators from the Karolinska Institute in Sweden and the National Institute of Child Health and Human Development in the U.S. The abstract is available here.

In this study, tobacco users had smaller babies than nonusers, although the reductions were modest. The average baby weight for nonusers was 7 pounds 14 ounces; babies of snus users weighed 7 pounds 13 ounces, while light smokers (1-9 cigarettes per day) and heavier smokers (10+ cigarettes) had babies that weighed less (7 pounds 8 ounces and 7 pounds 6 ounces, respectively).

Women who used snus were more likely than nonusers to have a premature delivery (adjusted odds ratio, aOR = 1.79, 95% confidence interval = 1.27 – 2.52), which was similar to that of light (aOR = 1.56, CI = 1.33 – 1.83) and heavier smokers (aOR = 1.84, CI = 1.53 – 2.21).

This study confirmed that smoking is protective for preeclampsia. The aOR for light smokers was 0.71 (CI = 0.59 – 0.88), and heavier smokers’ risk was even less (aOR = 0.48, CI = 0.36 – 0.64). However, snus users had a somewhat elevated risk for preeclampsia (aOR = 1.58, CI = 1.09 – 2.27).

In summary, pregnant women who use snus are at risk for slightly smaller babies, and they also have modestly elevated risks for premature delivery and preeclampsia. Women who are pregnant should refrain from using all tobacco products.

Note: The original link to the research study abstract was wrong. It was corrected on September 7, 2010.

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