Read time 4 minutes

pregnancy checks

Exposure to carbon monoxide presents a risk to you and your baby and can be caused by smoking during pregnancy or other environmental factors.

This article contains information on carbon monoxide testing in pregnancy. This can help you to reduce or eliminate your exposure and understand the measurements of your CO levels.

Carbon monoxide (CO) is a colourless, odourless and tasteless poisonous gas present in exhaust fumes, faulty gas appliances, coal/wood fires, oil burning appliances and cigarette smoke. Smoking when you are pregnant is particularly detrimental to your baby’s health and development.

"Carbon monoxide exposure is especially risky when you are pregnant. It's risky because carbon monoxide affects a growing baby’s access to oxygen, which is needed for healthy growth and development."

You may be offered a screening test to assess your levels of CO exposure, or you can ask the midwife at any antenatal appointment to test you. Carbon monoxide testing when you are pregnant could highlight a household problem and prevent further exposure.

How the CO test is done

You breathe into a cardboard tube attached to a handheld monitor. The monitor then shows the reading on its screen, and your midwife will explain the result. 

High levels of CO?

The usual reason for a high level on the reading is exposure to cigarette smoke, either from your own smoking or contact with other people’s smoke. High levels can also mean you have a faulty gas or heating appliance at home or you have been in a car with a faulty exhaust. 

Your midwife can share with you ways of eliminating your exposure, and if you are a smoker, or someone you live with is a smoker, then she can signpost you to support on quitting

Further information

Our support line offers practical and emotional support with feeding your baby and general enquiries for parents, members and volunteers: 0300 330 0700.

We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.

Smokefree offers NHS information on smoking while you are pregnant including a support DVD, cost calculators, 'stressbuster for the mind' and 'stress-buster for the body' MP3 downloads and a Quit app to help with support and encouragement.  

Smokefree also offers information specifically for fathers

NHS Pregnancy Smoking helpline is on 0800 169 9 169. The helpline is open Mon to Fri 9am to 8pm and Sat and Sun 11am to 5pm. You can also sign up to receive ongoing advice and support at a time that is convenient for you.

QUIT is the UK charity that helps smokers to stop and young people to never start. Information on smoking when you are pregnant is available as is information specifically for young smokers. 

Quitbecause offers information specifically for young smokers.

In June 2010, NICE published public health guidance on quitting smoking while you are pregnant and following childbirth. The guidance How to stop smoking while you are pregnant and following childbirth guidance updates recommendations on smoking in NICE's clinical guideline on antenatal care.

Was this article useful?

Related articles

pregnancy checks

Courses & workshops

In-person NCT Antenatal course

Find out more

NCT Antenatal refresher course

Find out more
NCT Membership
Support NCT Charity by becoming a member
Excited couple holding pregnancy test
Sign up to our weekly Pregnancy & Baby Guide