Randomisation
The participants were randomly assigned to either the intervention group or the control group (ratio 1:1) at baseline by a computer-generated random sequence, using random permuted block randomisation sizes (four, six or eight). Proper concealment was accomplished through the use of external randomisation service (Clinical Trial Unit, Department of Clinical Medicine, Aarhus University, Denmark). Each participant´s Central Personal Register (CPR) number was entered in the computer program (Trialpartner) by a research midwife, and thereby each participant was allocated to a group. The researchers were involved in inclusion of the participants and while the intervention consisted of exercise, neither participants nor researchers were blinded to group allocation after the randomisation procedure. The statistician performing the analyses were not blinded to the group allocation due to the prespecified perprotocol analysis.