Diastasis Rectus abdominis is a common condition in pregnant and postpartum women, where the connective tissue between the two muscle bellies of the rectus abdominis muscle is stretched and weakened, causing an increased inter-rectus distance. Treatment of this condition aim to reduce the inter-rectus distance, and conservative treatment including therapeutic exercise is the primary treatment of choice. To date, there is no generally accepted protocol of therapeutic exercises for this condition, and the evidence as to which exercise modality is the most effective and feasible in reducing the inter-rectus distance in women presenting with diastasis rectus abdominis is both sparse and weak. As this condition occur during the last two trimesters of pregnancy and as there is a paucity of high-quality studies on a pregnant population, investigators will conduct a randomized controlled trial on the effect of a specific exercise program during pregnancy on diastasis rectus abdominis.

100 pregnant women in gestation week 25 presenting with diastasis rectus abdominis of ≥ 28 mm will be included. Participants will be allocated to either an intervention group or a control group by block randomization. The intervention group will participate in a 12-week specific exercise program, consisting of two group sessions and two self-managed sessions weekly. The control group will not participate in any exercise intervention; however, participants will be recommended to follow national guidelines for general exercise during pregnancy. Participants will be assessed prior to intervention, post intervention at gestation week 37, and 6 weeks, 6 and 12 months postpartum. The primary outcome measure will be change in the inter-rectus distance in mm, measured by two-dimensional ultrasonography.

Inclusion Criteria:

• healthy pregnant women
• in gestation week 25
• presenting with an inter-rectus distance of 28 mm or more at the level of the umbilicus, and/or 2 cm above and below the umbilicus at rest on initial assessment. Participants presenting with a protrusion along the Linea Alba will also be included, even if they do not meet the inclusion criteria with an inter-rectus distance of 28 mm or more
• Both primi- and multigravida women will be included, and there will be no limitations on number of fetuses

Exclusion Criteria:

• pregnancies where exercise is contraindicated
• serious illnesses regarding both mother and fetus
• inability to understand Scandinavian languages
• failure to complete and present an informed consent form
• presence of chronic physical or mental illness incompatible with the intervention

Exclusion criteria during the study period is stillbirth or premature birth before gestation week 37; onset of serious illnesses regarding both mother and foetus; and pregnancies where exercise is contraindicated

To ensure randomization to the two groups in the RCT, participants will, following baseline assessments, be allocated to the two groups by block randomization. Blocking will be masked and not stated in the protocol to avoid selection bias. The group allocation will be administrated by a research assistant, to ensure blinding of the assessor. This study is assessor blinded only, as participants and the physiotherapist running the intervention groups cannot be blinded.