Participants’ characteristics.

During pregnancy, increased hormonal levels contribute to ligament laxity of the pelvis and could predispose to lumbopelvic pain. The main objective of this study was to assess changes in pregnancy-related hormones, neuromechanical adaptations and clinical pain status throughout pregnancy. An exploratory objective was to examine the possible association between those variables. Twenty-eight pregnant women participated in the study. At each trimester, they provided a blood sample (to measure relaxin, estrogen and progesterone), completed questionnaires assessing clinical status (functional disability, risk of poor prognosis of prolonged lumbar disability, avoidance behaviors, anxiety and pain catastrophizing), and were asked to perform a flexion-relaxation task (erector spinae electromyography and trunk kinematics). Results showed that throughout pregnancy, nocturnal and diurnal lumbopelvic pain intensity and related-disability, risk of poor lumbopelvic pain prognosis as well as avoidance behaviors increased, while pain catastrophizing decreased. Neuromechanical characteristics of flexion-relaxation task, including low back muscle activity and trunk kinematics, were similar across the three trimesters. Positive correlations were found between disability and estrogen levels (changes between first and second trimester, p = 0.05), and estrogen and diurnal lumbopelvic pain intensity (change between second and third trimester, p = 0.02). A positive correlation was also found between weight and the Pelvic Girdle Questionnaire score (changes between second and third trimester, p = 0.05). Negative correlations were found between weight (change between first and second trimester) and lumbopelvic maximal angle (p = 0.003), FRP onset for pelvic (p = 0.04) and lumbopelvic (p = 0.003) angles as well as FRP cessation for lumbopelvic angle (p = 0.001). These results show that, in pregnant women, pain and disability are associated with hormonal changes rather than trunk neuromechanical characteristics during a flexion-relaxation task. These results suggest that the flexion-relaxation task may not be an appropriate proxy to study vertebral and pelvic muscle control in pregnant women.

妊娠期间，激素水平升高会导致骨盆韧带松弛，进而增加腰骶骨盆痛（lumbopelvic pain）的发病风险。本研究的主要目的是评估妊娠全过程中与妊娠相关的激素水平、神经力学适应情况以及临床疼痛状态的变化；探索性目的则为探究上述变量间的潜在关联。本研究共招募28名孕妇参与。在每个孕程阶段（孕早期、孕中期、孕晚期），受试者均需采集血样以检测松弛素（relaxin）、雌激素（estrogen）与孕酮（progesterone）水平；填写评估临床状态的问卷，内容涵盖功能障碍、持续性腰椎功能障碍不良预后风险、回避行为、焦虑及疼痛灾难化思维（pain catastrophizing）；并完成屈肌松弛任务（flexion-relaxation task），同步采集竖脊肌肌电图（erector spinae electromyography）与躯干运动学（trunk kinematics）数据。研究结果显示，妊娠全过程中，夜间与日间腰骶骨盆痛强度、相关功能障碍、腰骶骨盆痛不良预后风险及回避行为均呈上升趋势，而疼痛灾难化思维则有所下降。屈肌松弛任务的神经力学特征（包括腰背肌活动与躯干运动学指标）在三个孕程阶段间无显著差异。研究发现，功能障碍与雌激素水平（孕早期至孕中期的变化量，p=0.05）呈正相关；雌激素水平与日间腰骶骨盆痛强度（孕中期至孕晚期的变化量，p=0.02）亦呈正相关。体重与骨盆带问卷（Pelvic Girdle Questionnaire）得分（孕中期至孕晚期的变化量，p=0.05）同样呈正相关。体重（孕早期至孕中期的变化量）与腰骶骨盆最大活动角度（p=0.003）、骨盆角度的屈肌松弛相（flexion-relaxation phase，FRP）起始时刻（p=0.04）、腰骶骨盆角度的FRP起始时刻（p=0.003）以及腰骶骨盆角度的FRP终止时刻（p=0.001）均呈负相关。上述结果表明，在孕妇群体中，疼痛与功能障碍与激素水平变化相关，而非屈肌松弛任务中体现的躯干神经力学特征。本研究结果提示，屈肌松弛任务或许并非研究孕妇脊柱与骨盆肌肉控制机制的合适替代指标。