2. Materials andmethods
For a retrospective study, all women with a pre-pregnancy BMI of at
least 30 who had a singleton delivery at the Department of Obstetrics,
Hvidovre Hospital, Hvidovre, Denmark, between January 1, 2010,
and December 31, 2011, were considered for inclusion. Additionally,
womenwith a pre-pregnancy BMI of 20.0–24.9 who had a singleton delivery
at the study center were selected for inclusion in a control group.
On the basis of power calculations, it was determined that 455 women
would need to be included in the control group. All births on the 15th
and 30th of each month in the study period were identified and included
in this group. The study was approved by the Danish Data Protection
Agency (Jr.nr. 2012-41-0400). Informed consent from all study
participants had been obtained.