Introduction. Spine ailments in lumbosacral part are common problem that concerns most pregnant women and this is basic factor that limit their life activity. Expectant mothers that feel pain often does not search for effective treatment instead they prefer to rest in lying or sitting position, which often increases symptoms. Pregnancy causes number changes in woman organism. Generally they are the result of impulses from placenta and from the developing fetus. In the consequence of those changes there occur typical troubles for pregnant women like: arterial hypertension, gestational diabetes, digestive disorders or shortness of breath. Growing stomach makes that center of gravity shifts, while lordosis is deepening. In addition, hormonal changes directly affects musculoskeletal system. Relaxin makes ligaments more flexible and stretches the tendons increasing mobility of joints in the spine and pelvis. There are many reasons for having pain. It can be generated because of: spondylitis dysfunction, pathological ligaments or myofascial tension, inflammation of the sacroiliac joints or fracture of the sacrum. As a result of the loss of stabilization of lumbar section intervertebral disc is particularly vulnerable to overload and microtrauma what in some cases causes discopathy. Another reason for the pain is too excessively stretched or shrunken muscles which gives local or moved symptoms. Aim. The aim of this study was to evaluate pain of lumbosacral part of patients with different BMI then demonstration dependence between physical activity of pregnant, their pain suffering and evaluation of pain reliefing methods. Material and methods. The study was included in a group of 200 pregnant hospitalized women in the period from January 2016 to June 2016. The study was conducted in Gynaecological-Obstetrics Clinical Hospital of the University of Medical Sciences in Poznan. The study enrolled patients who reported pain lower back pain. Research tools were a questionnaire and rating scale of pain VAS. The patients responded to questions about the location and strength of pain, their physical activity and using painkillers. For statistical evaluation used the arithmetic average of the grades obtained in VAS, standard deviation minimum and maximum values. Also compared the size of individual groups of respondents. Results. Studies have shown that women who were obese before pregnancy significantly more likely experience back pain then patients with BMI in border standards. Studied patients who were physically active before pregnancy and during its duration less likely complain about the pain. Observations have also shown that women are reluctant to seek professional help. They prefer rest and limit physical activity to a minimum. Encouraging women to physical activity and consultation with physiotherapist can have positive effect in the prevention of pain in lumbosacral part.

Key words: lumbosacral pain, physical activity of pregnant, physiotherapy.