Carbon monoxide screening

Carbon monoxide (CO) is a colourless, odourless, and tasteless poisonous gas. You can't see it or smell it. It is present in cigarette smoke (not e-cigarettes), but also in faulty gas boilers and car exhaust fumes.

It replaces some of the oxygen carried by your red blood cells, which means less oxygen getting to your baby. It is dangerous because it slows your baby’s growth and development, and increases the risk of miscarriage, stillbirth and sudden infant death.

All women are offered screening for carbon monoxide:

  • You blow into a hand-held machine, called a CO monitor, which measures the level of CO in your body.
  • The more CO you have inhaled, the higher your CO reading will be.

This test can also show whether you’re inhaling harmful amounts of second hand smoke (passive smoking). If your CO reading is above 4 ppm you will receive advice from your midwife on stop smoking services or advised to contact the Health and Safety Executive gas safety line.

No. Electronic cigarettes do not contain carbon monoxide. E-cigarettes are fairly new and there are still some things we do not know. However, current evidence on e-cigarettes indicates they are much less risky than smoking. E-cigarettes do not produce tar or carbon monoxide, the 2 main toxins in cigarette smoke. Carbon monoxide is particularly harmful to developing babies. The vapour from an e-cigarette does contain some of the potentially harmful chemicals found in cigarette smoke, but at much lower levels.

For more information about stopping smoking please click on this link.