The prevalence of respiratory disease in pregnancy is increasing: the incidence of asthma generally is rising, and more women with chronic conditions such as cystic fibrosis are surviving into reproductive life.
Problems and special considerations
Both primarily obstructive and primarily restrictive disease may be exacerbated by the increased respiratory demands of pregnancy (although asthma often improves in pregnancy), with further worsening in labour. In addition, the physiological changes of pregnancy may further hinder respiratory function, in particular airway oedema, upward displacement of the diaphragm and reduced functional residual capacity. It is also important to remember the increased risk factors associated with obesity, smoking and kyphoscoliosis, any of which may complicate the underlying respiratory condition.
Management options
Morbidity and mortality related to respiratory disease were examined in the 2014 and 2017 Confidential Enquiries into Maternal Deaths. Issues highlighted include:
• The importance of pre-pregnancy counselling to prevent maternal cessation of medical therapy due to concerns of adverse fetal effects
• The need to screen for pulmonary hypertension in those with severe respiratory disease prior to pregnancy
• The under-appreciation by healthcare professionals of the severity of the disorder Clinicians must be familiar with the physiological changes of pregnancy affecting the respiratory system in order to understand the relevant pathophysiology (see Chapter 11, Physiology of pregnancy). Early antenatal assessment of the woman, including pulmonary function tests when appropriate, is essential. Ideally, this should be in the first trimester. If the condition is severe, pre-conception counselling may be advisable. The effect of the pregnancy and delivery may then be assessed in light of the physiological changes of pregnancy and the respiratory stresses of delivery. Specifically, pulmonary function tests will give an idea of how the mother might cope with labour.
Women with mild disease can be treated as normal. In more severe disease, regional analgesia and anaesthesia are usually indicated to reduce the stress and demands of labour. Continuous pulse oximetry is advisable throughout labour in severe disease. If operative delivery is required, regional techniques avoid the depressant effects of general anaesthetic drugs, but care must be taken in case of high regional blocks.
Key points
• Respiratory disease may be exacerbated by the physiological changes of pregnancy and the increased demands of the fetus.
• Careful antenatal assessment is important.
• Regional analgesia and anaesthesia are usually indicated.
Further reading
Bonham CA, Patterson KC, Strek ME. Asthma: outcomes and management during pregnancy. Chest 2018; 153: 515-27.
Knight M, Kenyon S, Brocklehurst P, et al.; MBRRACE-UK. Saving Lives, Improving Mothers’ Care: Lessons learned to inform future maternity care from the UK and Ireland Confidential Enquiries into Maternal Deaths and Morbidity 2009-12. Oxford: National Perinatal Epidemiology Unit, University of Oxford, 2014.
Knight M, Nair M, Tuffnell D, et al.; MBRRACE-UK. Saving Lives, Improving Mothers’ Care: Lessons learned to inform maternity care from the UK and Ireland Confidential Enquiries into Maternal Deaths and Morbidity 2013-15. Oxford: National Perinatal Epidemiology Unit, University of Oxford, 2017.