Guidelines suggest adding nicotine replacement therapies (NRT) to behavioural smoking cessation support in pregnant smokers because of their excellent safety profile and proved effectiveness in other groups of smokers.
However, there is a lack of good quality evidence on the effectiveness of NRT in pregnant smokers.
So a team of researchers based in France set out to assess the efficacy of 16 hour nicotine patches among 402 pregnant women aged over 18 years and between 12 and 20 weeks' gestation, who smoked at least five cigarettes a day.
Participants were randomised to receive either nicotine patches or placebo patches up to the time of delivery. Doses were individually adjusted to try to match participants' nicotine intake to that achieved by smoking.
Participants were assessed monthly and received behavioural smoking cessation support. The primary outcome measures were complete abstinence (confirmed by levels of carbon monoxide in expired air) and birth weight.
Nicotine patches offered no benefit over placebo in terms of increasing smoking cessation or birth weight.
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Complete abstinence was achieved by only 11 (5.5 percent) of women in the nicotine patch group and only 10 (5.1 percent) in the placebo patch group. The average time to the first cigarette smoked after target quit date was 15 days in both groups.
Average birth weight was 3065g in the nicotine patch group and 3015g in the placebo patch group.
Blood pressure was significantly higher with the nicotine patch than with placebo, suggesting that further studies with nicotine in pregnant smokers should control for blood pressure, they added.