Noting that poorly controlled asthma can lead to serious medical problems for pregnant women and their babies, the guidelines emphasise that asthma control is important for the health of the mother as well as the healthy development of her baby. They recommend a stepwise approach similar to the guidelines for children and non-pregnant adults, with medication increased or decreased depending on asthma severity.

William Busse, from the University of Wisconsin Medical School in Madison, USA, and chair of the NAEPP multidisciplinary panel that developed the guidelines, said: "Simply put, when a pregnant woman has trouble breathing, her foetus also has trouble getting the oxygen it needs. There are many ways we can help pregnant women control their asthma, and it is imperative that providers and their patients work together to do so."

The NAEPP report includes new medications that have emerged and updates treatment recommendations for pregnant women with asthma, based on a review of available data on the safety of asthma medications during pregnancy.

"The guidelines review the evidence on asthma medications used by pregnant patients," said Barbara Alving, acting director of the US National Heart, Lung and Blood Institute, which administers the NAEPP. "The evidence is reassuring, and suggests that it is safer to take medications than to have asthma exacerbations. The guidelines should be a useful tool for physicians to develop optimal asthma management plans for pregnant women."

Because asthma severity usually changes during pregnancy, the guidelines also recommend that pregnant patients with persistent asthma have their asthma checked at least monthly by a healthcare professional, and that clinicians who provide obstetric care should also be involved in the patient's asthma management.

A summary of the guidelines is published this month in the Journal of Allergy and Clinical Immunology.