In this study, we measured the lumbar lordosis of normal pregnant women throughout their pregnancies and studied the efficacy and importance of the postpartum isometric exercise. 40 healthy primigravid patients were randomly assigned to one of the control and exercise groups. The lumbar lordotic deviation increased significantly throughout the pregnancy (p less than 0.05). Second postpartum day values of lumbar lordotic deviation and depth decreased compared to the third trimester values (p less than 0.05). Sixth postpartum week values of lumbar lordotic deviation and depth were found to be increased when compared to the first trimester values in the control and exercise group (p less than 0.05). On the other hand, the sixth week values in the exercise group are significantly lower compared to the control group (p less than 0.05). For these measurements we have used a 'Lumbar Lordosis Measurement Device' which was constructed in our institute. Muscle testing showed that isometric exercise improves the functional status of the affected muscles during pregnancy. We therefore conclude that the usage of 'LLMD' during the follow-up examination of pregnant women is essential to evaluate the posture of the patients. Isometric exercise is very important in order to obtain a normal posture and muscle tonus postpartumly.