Adding nicotine patches to behavioral counseling did not improve quit rates among pregnant women who smoked, a randomized trial showed.

Only 9.4% of women assigned to nicotine patches remained abstinent from their quit date through delivery, compared with 7.6% of those who received placebo patches (OR 1.26, 95% CI 0.82 to 1.96), according to Tim Coleman, MD, of the University of Nottingham in England, and colleagues.

Nor were there any differences between the groups in adverse pregnancy and birth outcomes, although low compliance in both groups limits the ability to draw conclusions about the safety of nicotine-replacement therapy during pregnancy, the researchers reported in the March 1 issue of the New England Journal of Medicine.

The lack of efficacy is consistent with the results of two previous, smaller randomized trials and calls into question guidelines recommending the use of nicotine-replacement therapy to help pregnant women quit smoking.

“Together with the prior results and pending data that show the efficacy of a higher dose of nicotine-replacement therapy in pregnant women, the present findings suggest that guidelines for smoking cessation in pregnancy should be revised to encourage the use of only those interventions that have a secure evidence base - specifically, behavioral support,” the authors wrote.

Nicotine-replacement therapy is effective for helping nonpregnant individuals quit smoking, but its use in pregnant women - up to a quarter of whom continue to smoke - has not been proven.

Coleman and colleagues conducted their trial among 1,050 pregnant women treated at seven hospitals in England. The participants ranged in age from 16 to 50, were in weeks 12 to 24 of gestation at enrollment, smoked at least five cigarettes a day during pregnancy, and had smoked at least 10 a day before becoming pregnant.

All of the women received behavioral counseling about smoking cessation, which included up to one hour of support at enrollment provided by research midwives and additional support by telephone on the selected quit date and at three days and four weeks later.

Roughly half of the women received eight weeks of treatment with patches delivering 15 mg of nicotine per 16 hours (a standard dose) and the rest received placebo patches.

Abstinence from the chosen quit date through delivery - the primary outcome - was validated using exhaled carbon monoxide or salivary cotinine levels.

Although abstinence rates were significantly higher in the active treatment group one month after the quit date (21.3% versus 11.7%; OR 2.05, 95% CI 1.46 to 2.88), there was no difference between the groups for the primary outcome.

Compliance with the therapy was low, with only 7.2% of women who received nicotine patches and 2.8% of those who received placebo patches using them for more than one month.

The poor compliance might be explained by the greater clearance of nicotine and cotinine that occurs during pregnancy, which would reduce nicotine levels and possibly increase withdrawal symptoms, according to the researchers. Thus, a higher dose might be required to be effective.

Although the apparent lack of harm from nicotine patches should be interpreted with caution, it does support another randomized trial with a higher dose of nicotine-replacement therapy in pregnant women, the authors wrote.

But, according to Cheryl Oncken, MD, of the University of Connecticut Health Center in Farmington, “given that nicotine is a neuroteratogen in animals, it would be important, particularly in any studies using higher doses, to monitor the overall exposure to nicotine ... in order to ensure that exposure during the use of nicotine-replacement therapy did not exceed baseline exposure (i.e., cotinine concentrations during smoking).”

“Pending more data on the efficacy and safety of nicotine-replacement therapy during pregnancy,” Oncken wrote in an accompanying editorial, “this therapy cannot be recommended with any clinical certainty.”

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Primary source: New England Journal of Medicine
Source reference: Coleman T, et al “A randomized trial of nicotine-replacement therapy patches in pregnancy” N Engl J Med 2012; 366: 808-818.