The number of obese women is increa

The number of obese women is increasing worldwide.8 The prevalence of obesity among U.S. women aged 20 to 39 years has increased from 28.4% in 1999 –2000 to 34% in 2007–2008,9 and first trimester maternal obesity have doubled from 7.6% (1989) to 15.6% (2007) in the United Kingdom.10 In Sweden, the prevalence of prepregnancy obesity was 6% in 1993 compared with 12% in 2009. The objective of the present study was to estimate, in a large data set from the Swedish Medical Birth Registry, whether maternal obesity is associated with an increased risk for postpartum hemorrhage more than 1,000 mL and whether there is an association between maternal obesity and postpartum hemorrhage with retained placenta or postpartum hemorrhage attributable to atonic uterus or postpartum hemorrhage caused by lacerations in the birth canal