The Royal College of Midwives (RCM) has backed tests that determine whether an expectant mother smokes.
New NHS guidance dictates that pregnant women will now be asked to undergo breath tests to establish if they are smoking while expecting.
Approximately one in five expectant mothers smoke, which can result in an underweight baby and complications during pregnancy and labour.
The National Institute for Health and Clinical Excellence wants to encourage women not to smoke by testing them for carbon monoxide during antenatal appointments. Smokers who record high levels will be offered support.
RCM chief executive Cathy Warwick said midwives play a vital role in promoting public health and reducing smoking in pregnancy. Fellow midwives have indicated to her just how helpful the tests are in making pregnant women aware of the risks of smoking.
"Of course, not all women will want to take this test. Any test which becomes routine must be offered along with comprehensive information and women must be able to opt out," Mrs Warwick said.
"Tests can help midwives educate women in the hope that they reduce their baby's exposure to cigarette smoke but not all women will accept the test and it is only a partial solution."
Mrs Warwick added that more midwives would improve the situation. The current shortage makes it difficult for a midwife to develop a relationship with an expectant mother, she said.
Copyright Press Association 2013