Nicotine replacement therapy, in the form of nicotine patches, is commonly offered to pregnant women who smoke to help them to stop smoking, but this approach has limited efficacy in this population. Electronic cigarettes (e-cigarettes) are also used by pregnant women who smoke but their safety and efficacy in pregnancy are unknown. Here, we report the results of a randomized controlled trial in 1,140 participants comparing refillable e-cigarettes with nicotine patches. Pregnant women who smoked were randomized to e-cigarettes (n = 569) or nicotine patches (n = 571). In the unadjusted analysis of the primary outcome, validated prolonged quit rates at the end of pregnancy in the two study arms were not significantly different (6.8% versus 4.4% in the e-cigarette and patch arms, respectively; relative risk (RR) = 1.55, 95%CI: 0.95–2.53, P = 0.08). However, some participants in the nicotine patch group also used e-cigarettes during the study. In a pre-specified sensitivity analysis excluding abstinent participants who used non-allocated products, e-cigarettes were more effective than patches (6.8% versus 3.6%; RR = 1.93, 95%CI: 1.14–3.26, P = 0.02). Safety outcomes included adverse events and maternal and birth outcomes. The safety profile was found to be similar for both study products, however, low birthweight (<2,500 g) was less frequent in the e-cigarette arm (14.8% versus 9.6%; RR = 0.65, 95%CI: 0.47–0.90, P = 0.01). Other adverse events and birth outcomes were similar in the two study arms. E-cigarettes might help women who are pregnant to stop smoking, and their safety for use in pregnancy is similar to that of nicotine patches. ISRCTN62025374.

尼古丁替代疗法通常以尼古丁贴片的形式提供给吸烟的孕妇，以帮助她们戒烟，但这种方法对这一人群的疗效有限。吸烟的孕妇也使用电子香烟（e-cigarettes），但其在怀孕期间的安全性和有效性尚不清楚。在这里，我们报告了一项对 1,140 名参与者进行的随机对照试验的结果，该试验比较了可填充电子烟和尼古丁贴片。吸烟的孕妇被随机分配到电子烟（n  = 569）或尼古丁贴片（n = 571）。在对主要结局进行的未经调整的分析中，两个研究组在妊娠末期经过验证的长期戒烟率没有显着差异（电子烟组和贴片组分别为 6.8% 和 4.4%；相对风险 (RR) = 1.55，95%CI：0.95–2.53，P  = 0.08）。然而，尼古丁贴片组的一些参与者在研究期间也使用了电子烟。在排除使用非分配产品的戒烟参与者的预先指定的敏感性分析中，电子烟比贴片更有效（6.8% 对 3.6%；RR = 1.93，95%CI：1.14–3.26，P = 0.02）。安全结果包括不良事件以及孕产妇和分娩结果。发现两种研究产品的安全性相似，但是，低出生体重（<2,500 克）在电子烟组中的发生率较低（14.8% 对 9.6%；RR = 0.65，95%CI：0.47–0.90，P  = 0.01）。两个研究组的其他不良事件和出生结局相似。电子烟可能会帮助孕妇戒烟，其在怀孕期间使用的安全性与尼古丁贴片相似。ISRCTN62025374。