GPs and midwives are failing to share information properly on pregnant women who are overweight or obese, a new report claims.
The Confidential Enquiry into Maternal and Child Health (CEMACH) study found 295 women died during pregnancy, after miscarriage, birth or after an abortion or ectopic pregnancy between 2003 and 2005.
The report said there were cases of "poor or nonexistent team working", "inappropriate or too short consultations by phone" and poor sharing of information.
It added that a "number of healthcare professionals failed to identify and manage common medical conditions or potential emergencies outside their immediate area of expertise".
CEMACH believes new national guidelines for medical staff are "urgently required" for obese pregnant women and those suffering sepsis.
New guidelines are also needed on pain and bleeding in early pregnancy, it added.
Dr Gwyneth Lewis, director of the inquiry, said the report overall shows the impact a mother's health can have on her pregnancy.
"Healthy mothers have healthier pregnancies and healthier babies," she said.
"The fact that more than half of the women who died were obese or overweight, and that preventable causes of cardiac disease were the leading cause of death, shows that strong public health messages are needed both before and during pregnancy."