The case for targeting pregnant smokers is clear. Smoking is the single most modifiable risk factor for adverse outcomes in pregnancy – maternal smoking causes up to 5,000 miscarriages, 300 perinatal deaths and around 2,200 premature singleton births each year.

Smoking in pregnancy and exposure to second-hand smoke is also strongly associated with cot death. Then there are the longer-term links to ADHD, obesity and type 2 diabetes.