When a woman becomes pregnant her body undergoes tremendous changes hormonally and anatomically. Our survey revealed very little literature on biomechanics of gait in gravidas and lack of consensus among scientists in pregnancy-related mechanisms of body adaptation. That is why the authors felt encouraged to determine the effect of pregnancy on the biomechanical pattern of walking. To investigate alterations in natural locomotion, we used a 3D motion-analysis system Vicon. The inclusion criteria aimed at selecting only healthy subjects (n = 13). Each woman participated in 3 sessions: before pregnancy, during the last trimester of gestation and, finally, half year after delivery. For the purpose of this study, selected kinematic parameters for pregnant and non-pregnant conditions were compared. Gravid women performed lower velocity of their gait and lower frequency of steps. The length of their step decreased in comparison to pre pregnancy state. The results did not reveal any changes in the range of motion of the ankle, knee and hip in different physiological conditions. However, we observed increased base of support and double support phase in gravidas comparing to non pregnant states (by about 10%). This finding indicates that there is a tendency to maximize safety in gait during pregnancy.