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Obesity may increase risk of postpartum hemorrhage

Sept. 23, 2011

By Patricia Nicholson

Women who are obese may have a significantly higher risk of postpartum hemorrhage (uncontrolled bleeding after childbirth) compared to women with a normal BMI.

Swedish researchers used data on more than 1,110,000 single births in Sweden between 1997 and 2008. The researchers compared the incidence of postpartum hemorrhage between six BMI categories: underweight (BMI under 18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-19.9), obese class I (BMI 30-34.9), obese class II (BMI 35-39.9), obese class III (BMI of 40 or more).

In the group as a whole, postpartum hemorrhage occurred in 4.5 out of every 100 women, but increased with BMI.

The researchers calculated that for women who had a regular vaginal delivery, risk of hemorrhage was 14 per cent higher in women with class I obesity compared to women with normal BMI. In women with class II and III obesity, the risks were 25 per cent higher and 23 per cent higher.

In women who had an instrumental vaginal delivery (using forceps or vacuum), hemorrhage risk increased by 26 per cent, 54 per cent and 69 per cent in obesity classes I, II and III, compared to normal-weight women.

Hemorrhage risk was also increased in obesity classes II and III for women who had caesarean deliveries: 30 per cent higher and 17 per cent higher compared to normal-weight women.

Since postpartum hemorrhage can have serious health effects, it’s important to be aware of increased risks in obese women.

The study was published in the September 2011 issues of Obstetrics & Gynecology.




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  • A publication of:
  • Women's College Hospital