Women are dying needlessly from conditions that develop or worsen during pregnancy because of a shortage of specialist doctors.

Maternal deaths caused by conditions such as heart disease, asthma and epilepsy have doubled in the past 20 years, the British Medical Journal reports.

Britain has only five obstetric physicians – specialists who treat pregnant women – and the BMJ says there is an urgent need for more to be trained. Professor Catherine Nelson-Piercy, the co-author of the BMJ article and an obstetric physician at Guy's and St Thomas's Foundation Trust in London, said the failure to train specialists meant the seriousness of seemingly minor symptoms such as chest pain, breathlessness and headaches were often missed.

Obesity and age increase women's risk of diabetes, high cholesterol and high blood pressure – conditions that can cause serious complications and should be closely monitored, the BMJ says.