Background: Nicotine and many other components of tobacco smoke are known carcinogens and mutagens, which can harm developing fetuses. Pregnant women who smoke have twice the risk of delivering a preterm (less than 37 weeks of gestation) or low–birth-weight (less than 5 lb, 8 oz [2,500 g]) infant compared with those who do not smoke. Most women who smoke continue smoking during pregnancy, and behavior modifications and counseling yield quit rates of up to only 18 percent. Oncken and colleagues studied whether nicotine replacement therapy (2 mg nicotine gum) was a safe and effective adjunct for smoking cessation during pregnancy. Intermittent nicotine dosing is recommended in pregnancy because it seems to deliver a lower amount of nicotine than smoking or continuous dosing (e.g., nicotine patch).
The Study: The double-blind, placebo-controlled trial included pregnant women older than 16 years who smoked at least one cigarette per day and planned to carry the pregnancy to term. Participants from three sites in Connecticut and Massachusetts were randomized to receive six weeks of nicotine gum (100 women) or placebo (94 women). Participants were instructed to replace each cigarette smoked with one piece of nicotine gum, up to 20 pieces per day. Individual smoking cessation counseling was provided at baseline and the first visit (within one week of the quit date). Adverse effects were assessed at subsequent visits (two, three, and six weeks after the quit date). Twice-monthly phone calls and follow-up appointments at 32 to 34 weeks of gestation and at six to 12 weeks postpartum also monitored progress. Overall nicotine levels were measured by concentration of urine cotinine, the major nicotine metabolite, at baseline and subsequent visits.
Results: Enrollment was stopped before reaching the planned 268 recruits because interim data failed to show effectiveness in the treatment groups. Participants using the nicotine gum were significantly more likely to attend study visits than those using placebo, especially the post-partum visit. However, smoking cessation rates did not differ significantly between the two groups at any point during the study. In the nicotine replacement group, birth weight was significantly higher than in the placebo group (7 lb, 3 oz [3,287 g] versus 6 lb, 8 oz [2,950 g]), and there was a nonsignificant trend toward increased gestational age.
Conclusion: The authors conclude that nicotine gum does not improve smoking cessation rates in pregnant women, but neonate birth weight is significantly increased to the average weight of neonates born to nonsmokers.
editor's note: Providing consistent support to smokers, including regularly assessing their motivational level and readiness, can assist in smoking cessation. Pharmacologic methods, such as bupropion (Zyban) and varenicline (Chantix), and nicotine replacement therapies can be effective as well. However, their safety in pregnancy is not fully known, and physicians—especially those not providing prenatal care—may be uncomfortable prescribing them. Clinical practice guidelines from the U.S. Department of Health and Human Services recommend that pharmacotherapy be considered when a pregnant woman is otherwise unable to quit and when its potential benefits outweigh the risks of pharmacologic therapy and continued smoking.1
As pregnant women continue to see their family physicians during pregnancy, for themselves or their children, multiple opportunities exist to assess and assist in smoking cessation. Although not definitive, this study suggests that the use of nicotine gum leads to lower nicotine exposure for the mother and the developing fetus.—a.c.f.