Obesity as a moderator of lumber spine posture change during pregnancy

Low back pain is one of the most common orthopedic issues during pregnancy, sometimes linked to a "gestational lordosis" spine posture. The aims in this study were to explore how the lumbar spine changes, establish the relationship of lumbar curvature to torso anthropometry, and determine if anthropometry can be used to predict lumbar angle changes during pregnancy.

Anthropometry and comfortable standing spine curvature were measured longitudinally during the last seven months of pregnancy of eleven pregnant participants. Multiple regression analyses were used to determine correlates at each time point. Auto- and cross-correlations were used to determine predictors of lumbar spine curvature.

Comfortable standing lumbar spine curvature was not correlated with gestational time (r² ≤ 0.031) and did not have a high autocorrelation indicating the inappropriateness to assume a single lumbar spine postural change during pregnancy. However. lumbar curvature was correlated with individual anthropometry (r² = 0.489) and those same measures can be used to predict lumbar posture change between the 1st trimester and the 3rd trimester of pregnancy.

Findings from this study can be applied to better predict pregnancy spine posture based on unique abdominal size increases relative to body size. Clinicians can use measures related to pre-pregnancy body mass index and torso mass gains to plan for ergonomic device use and work accommodation plans. Musculoskeletal models should consider that lower and higher BMI individuals may present with different loading patterns due to differences in lumbar spine posture change.