Anthropometry, standing posture, and body center of mass changes up to 28 weeks postpartum in Caucasians in the United States

Sensory integration and segmental control of posture during pregnancy

BACKGROUND

Approximately 25% of pregnant people fall, yet the underlying mechanisms of this increased fall-risk remain unclear. Prior studies examining pregnancy and balance have utilized center of pressure analyses and reported mixed results. The purpose of this study was to examine sensory and segmental contributions to postural control throughout pregnancy using accelerometer-based measures of sway.

METHODS

Thirty pregnant people (first trimester: n = 10, second trimester: n = 10, third trimester: n = 10) and 10 healthy, nonpregnant control people stood quietly for one minute in four conditions: eyes open on a firm surface, eyes closed on a firm surface, eyes open on a foam pad, and eyes closed on foam. Postural sway was quantified using the root mean square accelerations in the anterior-posterior and medial-lateral directions from an inertial sensor at the lumbar region. Sensory sway ratios, segmental coherence and co-phase, were calculated to assess sensory contributions and segmental control, respectively.

FINDINGS

Pregnant people did not display greater sway compared to healthy, nonpregnant controls. There were no group differences in vestibular, visual, or somatosensory sway ratios, and no significant differences in balance control strategies between pregnant and nonpregnant participants across sensory conditions.

INTERPRETATION

The small effects observed here contrast prior studies and suggest larger, definitive studies are needed to assess the effect of pregnancy on postural control. This study serves as a preliminary exploration of pregnant sensory and segmental postural control and highlights the need for future to hone the role of balance in fall risk during pregnancy.

Knowledge Mapping Analysis of Research on Pregnancy-Related Pelvic Girdle Pain (PPGP) from 2002 to 2022 Using Bibliometrics

Background

Pregnancy-related Pelvic Girdle Pain (PPGP) is a prevalent condition characterized by various physiological and pathological processes in the female body. The objective of this study is to offer a comprehensive understanding of the current research landscape, key areas of interest, and potential future directions in the field of PPGP.

Methods

Using Web of Science, we explored PPGP literature from 2002 to 2022. VOSviewer and CiteSpace facilitated a quantitative analysis, revealing co-authorship patterns, co-occurring themes, citations, and co-citations.

Results

We identified, peaking at 99 publications in 2021. The United States led with 138 publications and the highest citation count (3160). The Karolinska Institute boasted the highest tally of publications (n = 21). Regarding the volume of publications, the esteemed journal of BMC Pregnancy and Childbirth attained the foremost position. Notably, Gutke, Annelie emerged as the most prolific and highly cited author. The analysis of keyword co-occurrence and co-citation clustering unveiled an intricate tapestry of PPGP studies, spanning various domains including risk factors, mechanistic intricacies, diagnostic benchmark, treatment modalities, and far-reaching ramifications on one's quality of life.

Conclusion

Research endeavors exploring PPGP have unveiled an enduring trajectory of growth in contemporary times. The existing body of research primarily focuses on delving into the intricate interplay of epidemiological factors and the profound implications of interventions encompassing physical therapy, exercise protocols, and diverse modes of pain management within the domain of PPGP. Multidisciplinary integration encapsulates a prevailing trajectory of progress within this domain, while the focal point of future inquiries into PPGP may revolve around subjects pertaining to standardized outcome reporting.

Determining fall risk change throughout pregnancy: the accuracy of postpartum survey and relationship to fall efficacy

All epidemiological studies on pregnancy fall risk to date have relied on postpartum recall. This study investigated the accuracy of postpartum recall of falls that were reported during pregnancy, including assessment of fall efficacy as a possible reason for recall inaccuracy. Twenty participants reported fall experiences weekly during pregnancy, but one participant was excluded as an outlier. A fall efficacy questionnaire was completed every six weeks during pregnancy. A postpartum survey to mimic previous studies (Dunning, Lemasters, and Bhattacharya 2010; Dunning et al. 2003) was delivered to determine recall accuracy. Postpartum recall of fall events each gestational month matches the previous study (Dunning, Lemasters, and Bhattacharya 2010). However, recall of falls is 16% underestimated and recall of all fall events is 30% overestimated in postpartum survey. There is a slight relationship between fall efficacy and true falls, but not between fall efficacy and fall recall. Our study suggests fall risk needs to be intermittently surveyed throughout pregnancy rather than assessed via postpartum survey.Practitioner summary: This study investigated the accuracy of postpartum survey of fall risk during pregnancy and the possibility of fall efficacy as a covariate. We used three corresponding surveys. We found inaccuracies in postpartum survey, not explain by fall efficacy.

Assessment of physical fitness during pregnancy: validity and reliability of fitness tests, and relationship with maternal and neonatal health - a systematic review

Objectives

To systematically review studies evaluating one or more components of physical fitness (PF) in pregnant women, to answer two research questions: (1) What tests have been employed to assess PF in pregnant women? and (2) What is the validity and reliability of these tests and their relationship with maternal and neonatal health?

Design

A systematic review.

Data sources

PubMed and Web of Science.

Eligibility criteria

Original English or Spanish full-text articles in a group of healthy pregnant women which at least one component of PF was assessed (field based or laboratory tests).

Results

A total of 149 articles containing a sum of 191 fitness tests were included. Among the 191 fitness tests, 99 (ie, 52%) assessed cardiorespiratory fitness through 75 different protocols, 28 (15%) assessed muscular fitness through 16 different protocols, 14 (7%) assessed flexibility through 13 different protocols, 45 (24%) assessed balance through 40 different protocols, 2 assessed speed with the same protocol and 3 were multidimensional tests using one protocol. A total of 19 articles with 23 tests (13%) assessed either validity (n=4), reliability (n=6) or the relationship of PF with maternal and neonatal health (n=16).

Conclusion

Physical fitness has been assessed through a wide variety of protocols, mostly lacking validity and reliability data, and no consensus exists on the most suitable fitness tests to be performed during pregnancy.

PROSPERO registration number

CRD42018117554.

Changes in static balance during pregnancy and postpartum: A systematic review

BACKGROUND

Because pregnant women show a high risk of falling, some researchers examined their balance during static standing. This systematic review summarized the findings from all studies evaluating static balance in women during pregnancy and postpartum.

RESEARCH QUESTION

Do pregnant and postpartum women show differences in static balance compared to non-pregnant women, and does static balance change during pregnancy and postpartum?

METHODS

Pubmed, Embase, CINAHL, and Web of Science databases were searched systematically from inception until Feb 23, 2022. Studies were eligible for inclusion if they measured COP sway with a force plate during bipedal static standing, and compared COP outcomes between healthy pregnant or postpartum women and non-pregnant women, and/or during different stages of pregnancy and the postpartum period. Methodological quality was assessed overall with a modified version of the Downs and Black checklist, and specifically related to COP measurement by using recommendations of Ruhe et al. (2010). The protocol was registered in PROSPERO (CRD42020166302).

RESULTS

Thirteen studies were included. Because methodological approaches varied greatly between studies, results were summarized descriptively. Studies reported either greater overall and anteroposterior COP sway magnitude, velocity and variability in women from the second half of pregnancy until six months postpartum compared to non-pregnant controls, or no differences in static balance. Changes in static balance throughout pregnancy were generally not found. Finally, there was no clear consensus on the influence of pregnancy on the reliance on visual inputs for balance control, and on whether differences in balance in pregnant and postpartum women reflect poorer balance or positive adaptations to the physical changes experienced during pregnancy.

SIGNIFICANCE

Methodological heterogeneity between studies prevented us from drawing strong conclusions regarding the effect of pregnancy on static balance. Assessing the methodological quality of the studies revealed weaknesses that should be taken into account in future studies.

Progressive Changes in Lumbopelvic Alignment during the Three Month-Postpartum Recovery Period

Pregnancy-related lumbopelvic pain is a common musculoskeletal problem, and postural changes are believed to be involved in these disorders. However, the lumbopelvic alignment changes in postpartum women remain unclear. This study aimed to determine whether there are changes in lumbopelvic alignment following vaginal or cesarean delivery and when these alignment changes occur after delivery. Thirty postpartum females (PP group) and 20 nulliparous female controls (CTL group) underwent anteroposterior, lateral pelvic, and lower-back X-ray in a static upright position. Digital radiographic images were analyzed and three radiographic variables, the pelvic incidence, pubic symphysis width, and sacral slope, were measured. The pubic symphysis width of the PP group was significantly larger immediately and one month after childbirth (PP group: 6.0 ± 1.1 mm (immediately), 5.0 ± 1.2 mm (one month); CTL group: 3.4 ± 0.4 mm; F = 31.79, p < 0.001). The sacrum slope in the PP group was significantly larger than in the CTL group 1 month after childbirth (PP group: 39.9 ± 6.6°; CTL group: 32.8 ± 5.1°; F = 2.59, p = 0.05). A two-way analysis of variance indicated no statistically significant main effects or interaction effects between the delivery modes on the pubic symphysis width or the sacrum slope. This study suggested that the course of lumbopelvic alignment progressed towards recovery for at least one month, and that these changes were independent of the delivery method.

Mechanisms Underlying Lumbopelvic Pain During Pregnancy: A Proposed Model

Up to 86% of pregnant women will have lumbopelvic pain during the 3rd trimester of pregnancy and women with lumbopelvic pain experience lower health-related quality of life during pregnancy than women without lumbopelvic pain. Several risk factors for pregnancy-related lumbopelvic pain have been identified and include history of low back pain, previous trauma to the back or pelvis and previous pregnancy-related pelvic girdle pain. During pregnancy, women go through several hormonal and biomechanical changes as well as neuromuscular adaptations which could explain the development of lumbopelvic pain, but this remains unclear. The aim of this article is to review the potential pregnancy-related changes and adaptations (hormonal, biomechanical and neuromuscular) that may play a role in the development of lumbopelvic pain during pregnancy. This narrative review presents different mechanisms that may explain the development of lumbopelvic pain in pregnant women. A hypotheses-driven model on how these various physiological changes potentially interact in the development of lumbopelvic pain in pregnant women is also presented. Pregnancy-related hormonal changes, characterized by an increase in relaxin, estrogen and progesterone levels, are potentially linked to ligament hyperlaxity and joint instability, thus contributing to lumbopelvic pain. In addition, biomechanical changes induced by the growing fetus, can modify posture, load sharing and mechanical stress in the lumbar and pelvic structures. Finally, neuromuscular adaptations during pregnancy include an increase in the activation of lumbopelvic muscles and a decrease in endurance of the pelvic floor muscles. Whether or not a causal link between these changes and lumbopelvic pain exists remains to be determined. This model provides a better understanding of the mechanisms behind the development of lumbopelvic pain during pregnancy to guide future research. It should allow clinicians and researchers to consider the multifactorial nature of lumbopelvic pain while taking into account the various changes and adaptations during pregnancy.

Self-selection of gestational lumbopelvic posture and bipedal evolution

BACKGROUND

Not all pregnant women seem to select the more curved lumbopelvic posture that their sexual dimorphic anatomy allows even though many previous researchers have assumed lumbopelvic curvature to be standard during pregnancy. This study is vital to understanding coevolution of lumbopelvic sexual dimorphism and bipedalism, and understanding some clinical implications of intervening in gestational posture changes.

RESEARCH QUESTIONS

Are there anthropometric changes that correspond with selection of lumbopelvic curvature change during pregnancy? What are the biomechanical costs and benefits of gestational lumbopelvic curvature change?

METHODS

Twenty pregnant women were tested at five different times in the 2nd and 3rd trimesters of pregnancy. Lumbopelvic posture, standing kinetics and gait kinetics were measured longitudinally. Additionally, we modeled the effects on standing and gait without lumbopelvic postural changes, but with anthropometric changes, for each individual.

RESULTS

We found greater lumbopelvic angulation to correspond with a shorter body height (6 cm difference between groups, p = 0.048) and deeper 2nd trimester abdomen (2 cm difference between groups, p = 0.013). Lumbopelvic angulation lowers support requirements (in standing and walking (6% lower support impulse, p = 0.056), but at the cost of shifting the propulsive actions to a less efficient pulling action rather than pushoff (13 % reduction in pushoff time, p = 0.001). We observed minimal effects on walking kinematics and balance control.

SIGNIFICANCE

Our findings suggest the evolutionary advantage of the female lumbopelvic unit is the adaptability it provides to adjust for the individual needs of the pregnant woman. We discuss multiple potential contributing factors that may have shaped hominin female lumbopelvic evolution and are involved in self-selecting lumbopelvic posture.

Shoulder and elbow requirements during sagittal reach as a result of changing anthropometry throughout pregnancy

During pregnancy, anthropometric and physiological changes can result in difficulty reaching for and lifting everyday objects. The aims of this study were to determine the changes in sagittal plane anterior reach space (SPARS) and shoulder/elbow strength requirements throughout pregnancy. Seventeen participants were tested through a longitudinal observational cohort study between 16 and 36 weeks gestation in four-week intervals. A 25% decrease in SPARS was observed at the L3-4 torso height. Combined with arm mass increases, shoulder and elbow moment requirements at the minimum and maximum static reach distances significantly increased. However, inverse dynamics analysis determined that mass gains in the arm alone only minimally impact dynamic shoulder moments. Additionally, torso flexion increases throughout pregnancy demonstrates that women are attempting to compensate for decreased SPARS, possibly indicating the additional perceptual importance of reach space in accommodations for pregnant workers.

Impact of parity on biomechanical risk factors for knee OA initiation

BACKGROUND

Women are twice as likely as men to develop knee osteoarthritis (OA), and with it experience greater losses of physical function and disability. A change in the mechanical environment of the joint is a key initiating factor for knee OA. Differences in morphology, joint injury risk, and hormonal shifts in mid-life are often considered factors which increase OA risk for women. Pregnancy, a time of significant hormonal, morphological, and biomechanical change, has received comparably less attention. If morphological and biomechanical changes persist postpartum, this could increase OA risk for parous (childbearing) women.

RESEARCH QUESTION

Are lower limb gait mechanics different between healthy nulliparous (non-childbearing) and parous (childbearing) women?

METHODS

Twenty-eight self-reported not pregnant female participants (14 parous, 14 nulliparous) were recruited for the study. Nulliparous participants had never given birth to a child. Parous participants had given birth to at least one full-term infant (37-42 weeks) without complications between one to five years before data collection. Motion capture of participants' preferred, fast, and set (1.4 m/s) walking speeds was conducted. Repeated measures ANOVA were performed to test for significant group differences in joint kinematics and kinetics.

RESULTS

There was a significant main effect of group indicating a larger knee flexion angle at toe off (p = 0.0002), smaller knee extension moment at heel strike (p = 0.0006), smaller first peak knee flexion moment (p = 0.040), and smaller peak hip adduction moment for the parous group compared to the nulliparous group (p = 0.003). Static Q-angle did not differ between groups.

SIGNIFICANCE

Alteration in mechanics from the habitual loading pattern are thought to increase risk of OA. Smaller knee moments in post-partum women could alter the mechanical stimulus to cartilage, and should be investigated in conjunction with cartilage health measures to determine the link with OA initiation.

Correlations between joint kinematics and dynamic balance control during gait in pregnancy

BACKGROUND

Dynamic balance control degrades during pregnancy, but it is not yet understood why. Mechanical aspects of the body should directly affect walking balance control, but we have recently published papers indicating that weight gains during pregnancy explain very little dynamic balance changes. Our goal was to determine if lower extremity joint kinematic changes are an indicator of walking balance control. This information is vital to understanding the route by which pregnancy increases fall risk.

METHODS

Twenty-three pregnant women were tested at five different times in the 2nd and 3rd trimesters of pregnancy. Participants performed walking trials at a self-selected pace. Motion capture was used to measure joint kinematics (discrete and coordination variables) and body center of mass motion. Changes over time were statistically analyzed. Correlations between kinematics and walking balance were modelled with hierarchical multiple regression models.

RESULTS

As pregnancy progresses, it appears that a more flexed hip posture could be driving lower extremity kinematic changes toward increased coordination between joints and increased knee and ankle motions. Walking balance changes were also detected through increased COM motion (lateral range of motion and velocity) in the lateral directions. However, there was little correlation between kinematic and balance changes (r² < 0.4). Strong correlations were only observed when all kinematics (including those that don't ubiquitously change during pregnancy) were used in the regression model (r² > 0.7).

SIGNIFICANCE

Our findings suggest that walking balance control is not altered by a common kinematic change between all pregnant women. While increased lateral center of mass motion should be expected with pregnancy, the kinematics leading to this increase may be person-specific. The cause of dynamic imbalance in each pregnant women (physiological, mechanical, and neurocognitive) may play an important role in determining the kinematic means by which lateral center of mass motion increases.

An analysis of postpartum walking balance and the correlations to anthropometry

BACKGROUND

Falls caused by balance issues during pregnancy are quite common, and these issues can continue postpartum, potentially posing a danger to both the mother and baby. While there has been research on changes to walking gait during pregnancy, walking balance in the postpartum period has yet to be examined. Therefore, the aims of this study were to examine if balance changes persist in postpartum and the contribution of anthropometry changes.

METHODS

This was done through longitudinal observational cohort study at 16 and 40 weeks gestation and at four-week intervals postpartum. Balance was measured as lateral center of mass motion during treadmill walking, and recorded with motion capture cameras following anthropometric measurements. Balance variables were statistically analyzed to observe how they changed over time. Hierarchical regression analyses determined correlations between balance and anthropometry.

RESULTS

Balance was observed to improve significantly just following birth. Additionally, there were changes that continued to indicate improvement throughout the postpartum period. Anthropometry changes were significantly, but minimally, correlated with balance changes.

SIGNIFICANCE

Many women begin to return to normal activities soon after birth. With women participating in various forms of exercise, potentially rigorous work requirements, and tasks around the home, it is important that they, their medical providers, and employers understand and consider the continued risks of imbalance.