The purpose of this study is to examine the effect of supervised group exercise on mental wellbeing and signs of depression among pregnant women at risk of perinatal depression in a randomized controlled clinical trial.

The investigators hypothesis is that 70 minutes of supervised group exercise twice a week for 12 weeks by pregnant women at risk of perinatal depression, will improve the participants mental wellbeing and reduce their symptoms of depression.

Pregnant women with a current or a previous history of depression and/or anxiety have a significantly increased risk of perinatal depression and disruptions in the mother-infant attachment. In addition, pregnant women with anxiety and/or depression are at higher risk of preterm birth, low birth weight, and complications during birth.

It is well described that physical exercise in general is associated with psychological well-being and a reduced risk of morbidity and mortality in non-pregnant women. Several studies have documented that physical exercise during pregnancy is associated with health benefits for both infants and mothers. Physical exercise during pregnancy is associated with a lower risk of pregnancy- and delivery related complications such as preeclampsia, gestational diabetes mellitus, low back pain, preterm delivery, emergency caesarean section and postpartum depression, as well as contributing to improved mood.

Nevertheless, in the existing literature there are few and only small studies which have examined the effect of exercise on depression among mentally vulnerable pregnant women.

The aim of this study is to examine the effect of supervised group training for pregnant women with a current or a previous history of depression and/or anxiety.

Patient enrollment. The participants will be recruited from the Department of Obstetrics, Rigshospitalet, Denmark, from July 2016 to March 2019. Participants will be selected on the basis of 1) the information provided by the participants general practitioner and 2) an electronic questionnaire received by email and completed by all pregnant women registered to give birth at Rigshospitalet. The information from the questionnaire is routinely transferred to the pregnant women´s medical records.

The first contact to the participant will be made by phone at about 12-14 weeks of gestation, when, as a part of routine care, all mentally vulnerable pregnant women are contacted by a midwife from the Department of Obstetrics, Rigshospitalet. In this interview, the pregnant woman will be given brief information about the trial. If the woman is interested in further information, written participant information about the trial will be send. If the pregnant woman would like to participate in the project, an appointment for a personal meeting is made, where the participant is given more information about the project before written, informed consent is obtained and randomization can take place.

Data collection and management. Questionnaire number one, baseline data: all participants complete a baseline-questionnaire electronically and data are stored in a secured database.

Questionnaire number two (29-34 weeks of gestation) and questionnaire number three (two months after giving birth): the two questionnaires will be sent to the participants by email and the electronically answered questionnaires are stored in a secured database.

Other data will be obtained from patient records.

Sample size. The calculations have been made based on the primary endpoint, World Health Organisation Five Well-being Index (WHO-5) at 29-34 weeks of gestation. The WHO-5 wellbeing index score ranges from 0-100, where 100 is the best possible wellbeing. The average value measured by the WHO-5 wellbeing index at 10-12 weeks of gestation is 62 points with a standard deviation (SD) of 16. This has previously been assessed among pregnant women at the University Hospital, Rigshospitalet. For the calculations at 29-34 weeks of gestation we will use the SD observed at 10-12 weeks of gestation. The investigators expect that the effect of the intervention causes a 10 point higher WHO-5 index score in the intervention group than in the control group at gestational week 29-34, which is clinically significant ("Guide to the well-being index: WHO-5", Danish Health Authority).

It is estimated that 50% of the participants will be following the program for at least 75% of the sessions (high participation, 19-24 sessions) while 35% will be following 50-75% of the sessions (moderate participation, 12-18 sessions) and 15% will be following less than half of the sessions (low participation). The investigators expect that high participation in the training course will lead to an increase of 10 points in the WHO-5 wellbeing index, that moderate participation in the training course will lead to an increase of 7 points, while low participation will lead to an increase of 2 points, all compared to the control group.

This will lead to an average value in the intervention group which is 7.75 points (0.50 x 10 + 0.35 x 7 + 0.15 x 2) higher than the average value in the control group.

With a power of 90% and a two-sided significance level of 5%, a difference in wellbeing-level of 7.75 points (SD = 16) in the two groups at 29 - 34 weeks of gestation can be detected by a two-sample t-test with 91 patients in each group.

The investigators expect that it will be necessary to include a total of 300 pregnant women, as the investigators anticipate that 12.5% in each group will drop out because of discomfort or complications related to pregnancy and that 30% of the remaining 130 participants in each group will not answer the questionnaire at 29-34 weeks of gestation, which leaves 91 participants in each group.

Data analysis. The primary data analysis will be performed on the basis of the intention-to-treat principle. The investigators compare baseline data for the two groups with Student's t-test, chi-square test or non-parametric tests. A large proportion of missing values for the outcome variable is expected due to drop out and non-response to the questionnaire. Data will be assumed Missing At Random (MAR) and therefore observed patient characteristics will be used to impute missing data, by means of multiple imputation.

While it is expected that there will be a drop-out of 12.5% in each group, and that some pregnant women only participate in the group training a few times, the investigators will perform a per-protocol analysis of the pregnant women who performed ≥ 75% of all training sessions, in addition to the intention-to-treat analyses.

A pilot study with 9 women in the intervention group and 11 women in the control group, will be carried out from April - June 2016.

Inclusion Criteria:

• Pregnant women with depression and/or anxiety requiring treatment within the last ten years, and/or intake of antidepressants in the last three months before conception and/or during pregnancy.
• Age ≥18 years
• Singelton pregnancy
• 17th - 22th week of gestation by intervention start
• Appropriate Danish language skills
• Written informed consent

Exclusion Criteria:

• Age <18 years
• Multiple pregnancies
• Abuse problems
• Eating disorders
• Women who have been diagnosed with malformations or chromosomal disorder in the fetus
• Pelvic instability problems in earlier pregnancy (diagnosed by physiotherapist or doctor)
• Severe obstetric complications.

Withdrawal criteria. Participants will be withdrawal from the study after randomization, if one or more of the following criteria are met:

• Occurred pelvic instability
• Preeclampsia
• Vaginal bleeding
• Other factors indicating an increased risk of preterm birth.