Analysis of trunk movement for pregnant women with lumbopelvic pain using inertial measurement unit

Many women experience lumbopelvic pain (LPP) during pregnancy. It is thought that motion patterns, especially when accompanied by flexure and rotation of the trunk, are associated with LPP. This study investigates methods to evaluate the characteristics of the motion patterns that affect LPP during pregnancy. An experiment was conducted to obtain the motion characteristics of standing up and sitting down of pregnant women by using an inertial measurement unit (IMU). Then motion evaluation indexes were proposed from measured data of lumbar angular velocity obtained from the IMU. Next, the proposed indexes, maximum peak value, minimum peak value, peak-topeak (PP: range between maximum and minimum peaks) value, time of PP, PP divided by time of PP, root mean square of each parameter, and each index divided by body mass index (BMI), were calculated during standing up and sitting down for the roll, pitch, and yaw angles. Finally, we considered the presence of any relation between LPP and the motion characteristics by comparing the proposed indexes of an LPP group with those of a non-LPP group. Thus, it appears that maximum peak, PP/time of PP, maximum peak/BMI, PP/BMI, and (PP/Time of PP)/BMI of the pitch angle have some relevance to LPP.