It is estimated that 10% of pregnant women have a chronic medical disorder that requires regular use of medicines. In addition, some women develop health problems during pregnancy, and at least 40% take a prescription drug at some point.1,2 The impact of the increasing age and body mass index of the population has contributed to the proportion of women who require medication during pregnancy. For example, 4% of women delivering in England and Wales in 2011 were aged 40 years or over (compared with 1% in the 1990s) and 19% of women of child-bearing age in England in 2008 were obese.3,4 The relative lack of information on the use of medicines during pregnancy …