The biomechanics of pregnancy: a systematic review

This is the final version. Available from the publisher via the DOI/link in this record.During pregnancy, a number of biomechanical and hormonal changes occur that can alter spinal curvature, balance, and gait patterns by affecting key areas of the human body. This can greatly impact quality of life (QOL) by increasing back pain and the risk of falls. These effects are likely to be the ultimate result of a number of hormonal and biomechanical changes that occur during pregnancy. Research Question and Methodology: Using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, this systematic review sets out to analyse all available literature relating to the biomechanics factors caused by pregnancy and assess how this might reduce QOL. Fifty papers were deemed eligible for inclusion in this review based on the PUBMED and SCOPUS databases. Results: Angles of lordosis and kyphosis of the spine are significantly increased by pregnancy, but not consistently across all studies. Back pain is significantly increased in pregnant women, although this is not significantly correlated with spinal changes. Increased movements of centre of pressure (COP) and increased stability indexes indicate postural control is reduced in pregnancy. Trunk range of motion, hip flexion, and extension are reduced, as well as decreased stride length, decreased gait velocity, and increased step width; again, not consistently. It is likely that each woman adopts unique techniques to minimise the effects, for example increasing step width to improve balance. Further research should focus on how altered limb kinematics during gait might affect QOL by influencing the human body, as well as assessing parameters in all planes to develop a wider understanding of pregnant biomechanical alteration

The Effect of Lower Extremity Asymmetries on Low Back and Lower Extremity Pain with Pregnancy

Approximately 50% of pregnant women experience low back and lower extremity pain during pregnancy, many of which continue to experience pain post-partum. It is known that many women experience changes in foot size, arch height and lower extremity alignment. However, the mechanism by which these changes are related to pain is relatively unknown, specifically in regard to asymmetric changes in alignment. Therefore, the purpose of this study was to assess alignment during pregnancy in order to determine if asymmetries occurring in women during pregnancy are related to low back, hip, knee, and foot pain. Methods: Ten women in their third trimester of pregnancy and nine nulliparous controls were recruited to participate. Biomechanical measures of foot length, foot width, arch index, arch height index, arch rigidity index, arch drop, and rearfoot angle were taken bilaterally to assess asymmetry. Pelvic asymmetries were assessed in the frontal and sagittal plane. Musculoskeletal pain was assessed using a Visual Analogue Scale. Pregnant women were placed into a \u27pregnant pain\u27 group (n=5) and a \u27pregnant no pain\u27 group (n=5) based on results of this scale. Results/Conclusion: A relationship between lower extremity asymmetries and pain during pregnancy does exist. Specifically, negative correlations were found between arch index asymmetry and low back pain (p=0.005), foot length asymmetry and lower leg pain (p=0.008), and pelvic obliquity and lower leg pain (p=0.020). Significant positive correlations were found between foot width asymmetry and knee pain (p=0.028), as well as arch drop asymmetry and upper leg (p=0.024), knee (p=0.005), and lower leg pain (p=0.019). This study was successful in identifying a few target areas for clinicians to treat pain, but requires a much larger sample size in order to establish differences between pregnant women who experience no pain and pregnant women who do experience pain. Because low-back and lower extremity pain is extremely prevalent in post-partum women, it is important to conduct further research in order to determine both whether these asymmetries are related to pain post-partum, and if treating these asymmetries is preventative of pain post-partum

Effects of sex, age, body height and body weight on spinal loads: sensitivity analyses in a subject-specific trunk musculoskeletal model.

Subject-specific parameters influence spinal loads and the risk of back disorders but their relative effects are not well understood. The objective of this study is to investigate the effects of changes in age (35-60 years), sex (male, female), body height (BH: 150-190 cm) and body weight (BW: 50-120 kg) on spinal loads in a full factorial simulation using a personalized (spine kinematics, geometry, musculature and passive properties) kinematics driven musculoskeletal trunk finite element model. Segmental weight distribution (magnitude and location along the trunk) was estimated by a novel technique to accurately represent obesity. Five symmetric sagittal loading conditions were considered, and main effect plots and analyses of variance were employed to identify influential parameters. In all 5 tasks simulated, BW (98.9% in compression and 96.1% in shear) had the greatest effect on spinal loads at the L4-L5 and L5-S1 levels followed by sex (0.7% in compression and 2.1% in shear), BH (0.4% in compression and 1.5% in shear) and finally age (<5.4%). At identical BH and BW, spinal loads in females were slightly greater than those in males by ~4.7% in compression and ~8.7% in shear. In tasks with no loads in hands, BW-normalized spinal loads further increased with BW highlighting the exponential increase in spinal loads with BW that indicates the greater risk of back disorders especially in obese individuals. Uneven distribution of weight in obese subjects, with more BW placed at the lower trunk, further (though slightly <7.5%) increased spinal loads.This work was supported by the institut de recherche Robert-Sauvé en santé et en sécurité du travail 294 (IRSST-2014-0009) and the fonds de recherche du Québec en nature et technologies (FRQNT)

Low back pain incident, anthropometric characteristics and activities of daily living in pregnant women in a teaching hospital center antenatal clinic

Context: Although Low back pain (LBP) is a common problem during pregnancy, there is a death of empirical data on its etiology and possible risk factors especially in African population.Objective: The aim of this study was to investigate the relationship between LBP, anthropometric characteristics and Cumulative Index of Activities of Daily Living (CIADL) among pregnant women.Study design: A cross sectional survey sample of pregnant women (N=310) attending the antenatal clinic of University of Maiduguri Teaching Hospital was conducted using a close ended questionnaire to elicit information on socio-demographic characteristics, maternity record, activities of daily living functions performed as home chores and LBP experience. Anthropometric measurement of height, weight, waist circumference and hip circumference were also recorded.Result: A simple majority of the participants (52.3%) had LBP with lumbar type being predominant (55.1%). Majority of the pregnant women (55.6%) who experiences LBP were in their third trimester of pregnancy and pregnant women with formal education (X2=31.6, p=0.001) and civil servants (X2=5.8, p=0.03) tends to report LBP more than the others without education and of other occupation respectively. Primigravid women tend to report LBP more frequently than the multigravid (X2= 9.9, p=0.001) and parity was tenuously but inversely associated with LBP (r= -0.18 p= 0.002). While body weight was tenuously associated (r= 0.120 p= 0.035) with LBP, CIADL was not associated with LBP during pregnancy (r= -0.02, p= 0.71).Conclusion: The study affirms LBP as a common problem during pregnancy and this pain is unrelated to the intensity of chores performed by the cohorts of pregnant women in their homes.Trop J Obstet Gynaecol, 30 (1), April 201

Persistence of back pain symptoms after pregnancy and bone mineral density changes as measured by quantitative ultrasound - a two year longitudinal follow up study

<p>Abstract</p> <p>Background</p> <p>Previous research has shown a loss of bone mineral density (BMD) during pregnancy. This loss has been correlated to the occurrence of back pain symptoms during pregnancy. The objective of this study was to evaluate whether persistence of back pain symptoms 2 years after pregnancy could be associated with BMD changes as measured by quantitative USG of the os calcis.</p> <p>Methods</p> <p>A cohort of patients who reported significant back pain symptoms during pregnancy were surveyed for persistent back pain symptoms 24 to 28 months after the index pregnancy. Os calcis BMD was measured by quantitative ultrasound and compared with the BMD values during pregnancy.</p> <p>Results</p> <p>A cohort of 60 women who had reported significant back pain symptoms in their index pregnancy completed a 24-28 months follow-up survey and BMD reassessment. Persistence of significant back pain symptoms was seen in 24 (40%) of this cohort. These women had higher BMD loss during pregnancy compared to those without further pain (0.047 Vs 0.030 g/cm²; p = 0.03). Those that remained pain free after pregnancy appeared to have completely recovered their BMD loss in pregnancy, while those with persistent pain had lower BMD values (ΔBMD - 0.007 Vs - 0.025 g/cm²; p = 0.023) compared to their early pregnancy values.</p> <p>Conclusion</p> <p>Persistence of back pain symptoms after pregnancy could be related to an inability to recover fully from BMD loss during the index pregnancy.</p

Changes in foot posture during pregnancy and their relation with musculoskeletal pain: A longitudinal cohort study

Aim: To examine foot posture changes during the three trimesters of pregnancy and to determine whether there is a relationship between these changes and the pain experienced in this period. Methods: The study sample consisted of 62 pregnant women who attended the Gynaecology Service at Hospital Santa María del Puerto (Cádiz, Spain), between January 2013 and May 2014. In their first visit, the following sociodemographic and anthropometric data were recorded: age, weight, height and foot size. In addition, information was obtained regarding pain in the lower back, knees, ankles and feet. In this first visit, too, the Foot Posture Index (FPI) was assessed, and three subsequent controls were performed during the first, second and third months of pregnancy (termed Stages 1, 2 and 3, respectively). Results: In Stage 1, the average foot size (i.e., shoe size) was 38.3 (SD 1.5). This size did not change between Stages 1, 2 and 3. However, body weight and BMI did present statistically significant changes during this period (p < 0.0001). The FPI varied during pregnancy but no relation was observed between these changes and the onset of pain. Conclusions: During pregnancy, pronation increases but this does not appear to influence the onset of pain in the lower limb

Analysis of ground reaction forces in the second and third trimesters of pregnancy during walking

The objective of the current study was to examine the effect of pregnancy during the 2nd and 3rd trimesters on ground reaction forces (GRFs). Twenty-four non-pregnant women and forty-eight pregnant women in the second and third trimesters participated in this cross sectional study. Qualisys Gait Analysis System was used to analyze peaks and time parameters of GRFs in vertical (Fz), antero-posterior (Fy) and medio-lateral directions (Fx). The results showed that there were no significant differences between the non-pregnant and the pregnant women in the first peak (Fz1) (p=.147) and the second peak (Fz2) (p=.125) of vertical GRF, braking force (FyB) (p=.867) and propulsion force (FyP) (p=.929), as well as lateral (FxL) (p=0.994) and medial (FxM) GRF (p=.920). However, there was a significant increase in the Fz minimum (min) (p=.008), and a decrease in the difference between the Fz1 and Fz min (p=.042) and the difference between Fz2 and Fz min (p=.028). Moreover, there were increases in the time taken to reach the Fz1 (p=.024), Fz2 (p=.005), Fz min (=0.001), FyB (p=.010), FyP (p=.001), FxL (p=.010) and FxM (p=.011). These findings displayed that the pregnant women assumed a flatter pattern of vertical GRF and a decreased downward movement of center of gravity. This pattern may help to make the gait smooth and efficient. Increased time to reach peaks of GRFs may be a strategy to maximize balance during pregnancy

The Effect of Asymmetry on Pregnancy-Related Pain in the Postpartum Period

Nearly 50% of women experience back pain and other lower extremity pain during pregnancy, with many reporting lasting pain postpartum. Pregnant women experience changes to their pelvis and lower extremities that do not always return to pre-pregnancy baseline. Not much is known of the lingering effects of pregnancy related asymmetry and its relationship to pain. Therefore, the purpose of this study was to assess asymmetries of the pelvis and lower extremities to determine whether malalignment is related to areas of pain at the low back, hip, thigh, knee, leg, and foot/ankle. Methods: Seventeen postpartum women and seven nulliparous controls were recruited to participate. Postpartum women were placed in a ‘no pain’ and ‘pain” group based on a Visual Analog Scale pain questionnaire. Biomechanical measurements were taken bilaterally for: leg length, foot width, foot length, arch drop, arch index, arch height index, arch rigidity index, rearfoot angle, dynamic knee valgus, and hip muscular strength. Measurements of hypermobility and flexibility were taken using Beighton’s scale and Sit and Reach test. Results/Conclusion: Several relationships exist between pelvic and lower extremity asymmetry and pain in postpartum women. We identified multiple areas of asymmetry at the hip, knee, and foot that were correlated to pain. This information may be helpful to clinicians and the treatment of asymmetries during pregnancy to prevent pain postpartum. With the high prevalence of pain that still remains postpartum, further research is necessary. A larger sample size is needed to validate the trends found in this study regarding asymmetry and pain