There is a great lack of results from randomized clinical trials with high methodological quality, assessing the effects of exercise during pregnancy. The main aims of this trial is to study the effects of exercise during pregnancy in the prevention and treatment of disease and complications which may arise during pregnancy:

• Does regular exercise during pregnancy aid in preventing gestational diabetes?
• Does regular exercise during pregnancy prevent low back and/or pelvic girdle pain?
• Does regular exercise during pregnancy prevent urine and/or fecal incontinence?
• Does regular exercise during pregnancy have an effect on labour and delivery?
• Does regular exercise during pregnancy prevent maternal excessive weight gain and fetal macrosomatia?

Pregnancy is regarded as a period of high risk when it comes to development of e.g. excessive weight gain, gestational diabetes and musculoskeletal problems such as low back pain and pelvic girdle pain, and urinary and fecal incontinence. While pregnancy and labor imply these and other risks, exercise is regarded as advantageous during pregnancy. Today's knowledge about the importance of exercise during pregnancy is mainly based on observational data from epidemiological studies, and the scientific strength of the clinical recommendations given is open to question. There is a great lack of results from randomized clinical trials with high methodological quality, assessing the effects of exercise during pregnancy. As a result of this, many important questions are still not answered. One of these is the effect exercise during pregnancy has in the prevention and treatment of disease and complications which may arise during pregnancy. Another question is the consequences that exercise during pregnancy has for labor and delivery. This study is designed as a randomized clinical trial using validated measurement tools to find answers to the mentioned questions.

In both national and international literature the importance of physical activity is highlighted. WHO has recently presented a global strategy for nutrition, physical activity and health. In Norway physical activity and exercise have been strongly addressed, and is an issue of high priority also in pregnant and postpartum women (St.meld.nr.16). Nevertheless, few trials evaluating the effects of regular exercise have been published. There is a need for evidence based knowledge to be implemented in education of health professionals, and in the development of health promotion strategies aiming at the general population.

Inclusion Criteria:

• Pregnant 18 weeks
• attend the routine ultrasound control at the three hospitals
• healthy
• age 18 years or more
• singleton live foetus at the routine ultrasound scan
• normal pregnancy.

Exclusion Criteria:

• pregnancy complications
• high risk for preterm labour
• pain during pelvic floor muscle contractions
• ongoing urinary tract infection
• diseases that could interfere with participation (following recommendations from SEF 2000, ACOG 2003)
• living too far from the hospitals to be able to attend weekly exercise groups