Maternal smoking during pregnancy causes significant fetal morbidity and is a public health problem, as 36% of women in the UK and 11% of those in the US smoke during pregnancy. Behavioural support for smoking cessation, provided outside of routine antenatal care, is effective for promoting smoking cessation by pregnant women, but relatively few pregnant women access such support. Effective pharmacological aids to smoking cessation, which have been trialled in nonpregnant populations, include nicotine replacement therapy (NRT), bupropion and varenicline; however, there is very little evidence to justify the use of these drugs in pregnancy. Also, for safety reasons, it is doubtful that definitive trials investigating the effectiveness of either bupropion or varenicline for smoking cessation will be conducted in pregnant women in the foreseeable future. In the short to medium term, research information relating to the use of these drugs in pregnancy is, therefore, likely to be derived from observational studies that are more difficult to interpret than clinical trials.