More than 50% of women who die in pregnancy or shortly after birth are overweight or obese, a new report claims.
The Confidential Enquiry into Maternal and Child Health (CEMACH) study is now calling for better communication between staff to cut down the number of avoidable deaths due to other causes.
CEMACH is also planning to carry out a national investigation into obesity in pregnancy as a result of its concerns about the impact on mothers and babies.
The study focused on the number of women dying during pregnancy, after miscarriage, birth and after an abortion or ectopic pregnancy, between 2003-05.
Some 295 women died during that period, compared with 223 in 1985-87.
The report found six of the women who died had a body mass index (BMI) greater than 45, while two women had a BMI of more than 60. A healthy BMI is between 18.5 and 24.9.
It went on to say that the link between obesity and death will not be a surprise, but added: "The magnitude of this risk means that obesity represents one of the greatest and growing overall threats to the childbearing population of the UK."