MR obstetric pelvimetry: effect of birthing position on pelvic bony dimensions

Assessment of the pelvic and body interface pressure during different recumbent and semi-recumbent birthing positions

BACKGROUND

Childbirth, a multifaceted physiological event, undergoes dynamic changes influenced significantly by the chosen birthing position, impacting comfort and maternal and neonatal outcomes among other factors. This study aimed to investigate the bed-body interface pressure across five commonly adopted birthing positions, particularly focusing on their influence on pelvic expansion biomechanics during labour.

METHODS

Twenty healthy participants, aged between 18 and 49 years, were evaluated. Interface pressure across multiple regions of interest, including the head, shoulder, pelvis, and full body, were meticulously assessed under different combinations of leg and back positioning.

FINDINGS

Significant variations in interface pressure were observed based on chosen positions. Post hoc pairwise comparisons showed different pressure distributions for all regions of interest, with the combination of legs in stirrups and a flat back resulting in the lowest average pressure in the pelvic region. During the closed glottis pushing task, this combination exhibited lower peak pressure and peak pressure index in the pelvic region compared to other positions.

INTERPRETATION

While upright positions are conventionally preferred, the study underscores the nuanced implications of recumbent and semi-recumbent positions. Although using stirrups with a flat back exerts less pressure, lying flat can impede blood flow and exacerbate pain, while stirrups might lead to discomfort and potential complications. Given these complexities, healthcare providers must consider multiple factors to determine optimal birthing positions. The interplay between birthing positions and obstetric outcomes awaits further exploration and refinement, marking an exciting frontier in maternal care.

Updating of pelvimetry standards in modern obstetrics

Clinical value of pelvimetry in modern obstetrics practices has never been established and normal values are set since the middle of the twentieth century. The aim of this study was to describe current dimensions of pelvis in a female French Caucasian population. A retrospective, bi-centric observational study was conducted from August 2013 to August 2019 in two French departments of Obstetrics. We included all Caucasian women who had a computed tomography pelvimetry during pregnancy. The primary outcome was the values of the obstetric transverse diameter, obstetric conjugate diameter and bispinous diameter. Five hundred and fifty-one CT pelvimetries were analyzed. The median Obstetric Transverse Diameter (OTD) was 12.41 cm and the 3rd percentile was 11 cm. The median Obstetric Conjugate Diameter (OCD) was 12.2 cm and the 3rd percentile was 10.5 cm. The median Bispinous Diameter (BSD) in our data collection was 10.9 cm and the 3rd percentile was 9.3 cm. A significant correlation coefficient between women's height and OTD, OCD and BSD was found. In our study, the OCD and the BSD have not evolved since the middle of the twentieth century. The obstetric transverse diameter was smaller than the standard currently used.

The impact of femoral rotation on sacroiliac articulation during pregnancy. Is there evidence to support Farabeuf's hypothesis by finite element modelization?

BACKGROUND

Counter-nutation movement is deemed crucial during the management of the birth process. It is a combination of lateral ilia expansion and backward displacement of the promontory resulting from the external rotations of the femurs producing an enlargement of the pelvic inlet. However, since its description by Farabeuf, this mechanism has never been challenged and analyzed in a dynamic finite element study.

METHODS

Based on a female pelvic mesh and sacroiliac ligaments, we simulated external rotations of both femurs with imposed rotation of the two acetabulum centers. We hypothesize that lateral ilia expansion generates a sacrum movement resulting in a backward displacement of the promontory and a pelvic inlet enlargement.

RESULTS

Finite element simulation confirms our hypothesis and reveals that ilio-sacro-transverse and axile ligaments play an essential role in this mechanism. Indeed, the increase in stiffness (ranging from 500 MPa to 750 MPa) of these ligaments accentuates the counter-nutation movement and the opening of the inlet. Instead of the anatomic congruence between the ilium and the sacrum, the sacroiliac ligaments may explain the counter-nutation. After a 6° of femur rotation, the inlet area increases to 11 cm2 (141 cm2 vs. 130 cm2). This enlargement could be noteworthy in case of obstructed labor or shoulder dystocia. Moreover, the association between external rotation and flexion of the femurs could be more efficient for opening the pelvic inlet.

CONCLUSIONS

Our result did not support the original assumption of Farabeuf. By revealing how postural adjustment increases the bony birth canal, this study provides essential information for the clinical management of the delivery.

Magnetic resonance imaging pelvimetric measurements as predictors for emergent cesarean delivery in obstructed labor

Objective

This study aimed to investigate the usefulness of various magnetic resonance imaging (MRI) pelvimetric parameters for predicting emergent cesarean delivery due to obstructed labor.

Study design

This was a prospective observational study. MRI pelvimetry was performed in cases of a clinically suspected maternal narrow pelvis, maternal short stature, fetal overgrowth, and abnormal placental position. MRI pelvimetry was performed at 34.7 ± 4.2 gestational weeks using a 1.5 T MRI system. The pelvic inlet angle, pelvic inclination, obstetric conjugate, sacral outlet diameter (SOD), and coccygeal pelvic outlet were measured in the sagittal section. The interspinous diameter and intertuberous diameter were measured in coronal sections. Fetal anomalies, cesarean deliveries before the onset of labor, and non-reassuring fetal status were excluded from the analysis.

Results

MRI pelvimetry was performed in 154 patients. After excluding 76 cases, including 19 cases of absolute cephalopelvic disproportion, 78 cases of trial of labor were included. Of these, 63 were vaginal deliveries and 15 were emergent cesarean deliveries due to obstructed labor. The cut-off value for body mass index (BMI) was 22.2, with an area under the curve (AUC) of 0.69, for predicting obstructed labor. The cut-off value for the SOD was 10.7 cm with an AUC of 0.69. BMI alone had a sensitivity of 80%, specificity of 66%, positive predictive value (PPV) of 36%, and negative predictive value (NPV) of 93%. When BMI and SOD were combined, sensitivity was 53%, specificity was 90%, PPV was 57%, and NPV was 89%. The odds ratio for emergent cesarean delivery was 5.42 (95% confidence interval 1.06-27.6, p = 0.041) if the SOD was less than the cut-off value in the binomial logistic regression analysis in cases with an BMI > 22.

Conclusion

We confirmed that MRI pelvimetry was a reliable tool for better patient selection for obstructed labor. The SOD was the best predictor of obstructed labor, with a cut-off value of 10.7 cm for women with a low BMI.

Vacuum delivery in all-fours position: is it a valuable, brand-new option?

Since all-fours birth position is considered to decrease the rate of failure of vaginal birth and the risk of negative maternal and fetal outcomes, we wondered if all-fours would be favorable in case of operative vaginal delivery with obstetrical vacuum. We performed a simulation of vacuum application on a mannequin settled in all-fours position and we filmed this new application for diffusion among clinicians. We suggest that the all-fours position be considered and investigated in further studies as a possible way of delivery in case of operative vaginal delivery.

Squatting, pelvic morphology and a reconsideration of childbirth difficulties

 

Childbirth is commonly viewed as difficult in human females, encompassed by the 'Obstetrical Dilemma' (OD) described by early palaeoanthropologists as an evolved trade-off between a narrow pelvis necessitated by bipedalism and a large-brained fetal head. The OD has been challenged on several grounds. We add to these challenges by suggesting humans likely squatted regularly during routine tasks prior to the advent of farming societies and use of seats. We suggest that habitual squatting, together with taller stature and better nutrition of ancestral hunter-gatherers compared with later Neolithic and industrial counterparts, obviated an OD. Instead, difficulties with parturition may have arisen much later in our history, accompanying permanent settlements, poorer nutrition, greater infectious disease loads and negligible squatting in daily life. We discuss bioarchaeological and contemporary data that support these viewpoints, suggest ways in which this hypothesis might be tested further and consider its implications for obstetrical practice.

Lay Summary

Human childbirth is viewed as universally difficult. Evidence from physical therapies/engineering and studies of living and ancestral humans illustrates habitual squatting widens the pelvis and could improve childbirth outcomes. Obstetrical difficulties emerged late in prehistory accompanying settled agriculture, poorer nutrition and less squatting. Specific physical exercises could improve obstetrical practice.

Dynamic finite-element simulations reveal early origin of complex human birth pattern

Human infants are born neurologically immature, potentially owing to conflicting selection pressures between bipedal locomotion and encephalization as suggested by the obstetrical dilemma hypothesis. Australopithecines are ideal for investigating this trade-off, having a bipedally adapted pelvis, yet relatively small brains. Our finite-element birth simulations indicate that rotational birth cannot be inferred from bony morphology alone. Based on a range of pelvic reconstructions and fetal head sizes, our simulations further imply that australopithecines, like humans, gave birth to immature, secondary altricial newborns with head sizes smaller than those predicted for non-human primates of the same body size especially when soft tissue thickness is adequately approximated. We conclude that australopithecines required cooperative breeding to care for their secondary altricial infants. These prerequisites for advanced cognitive development therefore seem to have been corollary to skeletal adaptations for bipedal locomotion that preceded the appearance of the genus Homo and the increase in encephalization.

The pelvic anatomic index is an independent predictor for the difficulty of radical prostatectomy

OBJECTIVES

The aim of the study was to investigate whether a novel simple measurement of pelvic anatomy, the pelvic anatomical index (PAI), which is obtained from simple physical examination, was predictive for potential difficulty and adverse outcome in radical prostatectomy.

MATERIALS AND METHODS

Available data from 73 consecutive radical prostatectomy patients were analyzed. The distances between umbilicus and cranial edge of the symphysis pubis (USPD) and between root of the penis and umbilicus (PUD) were measured. PAI was obtained using the formula (PUD/USPD) × body mass index (BMI). Indicators of surgical difficulty assessed were operation time (OT), dorsal vein bleeding (DVB), total blood loss (TBL), and surgical margin (SM) status. Patients with below-median values of the OT, DVB, TBL, and had negative SM were grouped as favorable surgery (n = 18).

RESULTS

Median OT, DVB, and TBL were 215 (IQR: 187.5-240) min, 380 (IQR: 200-500) cc, and 1000 (IQR: 700-1300) cc, respectively. Both PAI and BMI were significantly correlated with TBL, DVB, and OT (p < 0.05, for all). PAI and BMI significantly associated with favorable surgery (p = 0,006 and p = 0.048, respectively). However, only PAI was an independent predictor of favorable surgery in multivariable logistic regression analysis. A PAI 36 kg/m² was determined as the threshold value for favorable surgery with 83.3% sensitivity and 60% specificity.

CONCLUSION

PAI significantly correlated with almost all surgical parameters and was a significant independent predictor of favorable surgery. PAI can enable the physician to select and discuss individualized treatment options for patients during preoperative planning.

Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches

The human pelvis shows marked sexual dimorphism that stems from the conflicting selective pressures of bipedal locomotion and parturition. The sacrum is thought to reflect this dimorphism as it makes up a significant portion of the pelvic girdle. However, reported sexual classification accuracies vary considerably depending on the method and reference sample (54%-98%). We aim to explore this inconsistency by quantifying sexual dimorphism and sex classification accuracies in a geographically heterogeneous sample by comparing 3D geometric morphometrics with the more commonly employed linear metric and qualitative assessments. Our sample included 164 modern humans from Africa, Europe, Asia, and America. The geometric morphometric analysis was based on 44 landmarks and 56 semilandmarks. Linear dimensions included sacral width, corpus depth and width, and the corresponding indices. The qualitative inspection relied on traditional macroscopic features such as proportions between the corpus of the first sacral vertebrae and the alae, and sagittal and coronal curvature of the sacrum. Classification accuracy was determined using linear discriminant function analysis for the entire sample and for the largest subsamples (i.e., Europeans and Africans). Male and female sacral shapes extensively overlapped in the geometric morphometric investigation, leading to a classification accuracy of 72%. Anteroposterior corpus depth was the most powerful discriminating linear parameter (83%), followed by the corpus-area index (78%). Qualitative inspection yielded lower accuracies (64-76%). Classification accuracy was higher for the Central European subsample and diminished with increasing geographical heterogeneity of the subgroups. Although the sacrum forms an integral part of the birth canal, our results suggest that its sex-related variation is surprisingly low. Morphological variation thus seems to be driven also by other factors, including body size, and sacrum shape is therefore likely under stronger biomechanical rather than obstetric selection.

A biomechanical study of the birth position: a natural struggle between mother and fetus

Birth trauma affects millions of women and infants worldwide. Levator ani muscle avulsions can be responsible for long-term morbidity, associated with 13-36% of women who deliver vaginally. Pelvic floor injuries are enhanced by fetal malposition, namely persistent occipito-posterior (OP) position, estimated to affect 1.8-12.9% of pregnancies. Neonates delivered in persistent OP position are associated with an increased risk for adverse outcomes. The main goal of this work was to evaluate the impact of distinct fetal positions on both mother and fetus. Therefore, a finite element model of the fetal head and maternal structures was used to perform childbirth simulations with the fetus in the occipito-anterior (OA) and OP position of the vertex presentation, considering a flexible-sacrum maternal position. Results demonstrated that the pelvic floor muscles' stretch was similar in both cases. The maximum principal stresses were higher for the OP position, and the coccyx rotation reached maximums of 2.17[Formula: see text] and 0.98[Formula: see text] for the OP and OA positions, respectively. Concerning the fetal head, results showed noteworthy differences in the variation of diameters between the two positions. The molding index is higher for the OA position, with a maximum of 1.87. The main conclusions indicate that an OP position can be more harmful to the pelvic floor and pelvic bones from a biomechanical point of view. On the other side, an OP position can be favorable to the fetus since fewer deformations were verified. This study demonstrates the importance of biomechanical analyses to further understand the mechanics of labor.

Can the Dynamic External Pelvimetry Test in Late Pregnancy Reveal Obstructed and Prolonged Labor? Results From a Pilot Study

Background The size and mobility of the maternal pelvic space are fundamental factors in successful childbirth and can allow operators to screen for dystocia. This pilot study including a group of 70 pregnant women aimed to test whether the external dynamic pelvimetry test can be used to predict the likelihood of obstructed labor. Methodology The study cohort consisted of 70 pregnant women in their third trimester. The cohort was divided retrospectively into an obstructed labor group and a control group. Obstructed labor was defined using the following obstetric outcomes: augmentation with oxytocin from the first phase of the dilating period, Kristeller's maneuvers, vacuum extractor (kiwi), forceps, and the cesarean section following the onset of labor. Results The measurements obtained for the longitudinal hemi-diameter of Michaelis, the inter-tuberous diameter, and the base of the Trillat's triangle were statistically significant in every position. The difference in the measurements of the transverse diameter of Michaelis between standing and hands-and-knees position and the difference in the sizes of the bi-cristal diameter between hands-and-knees and squatting position were statistically significant. Conclusions Dimension and biomechanical properties of the pelvic tissue and spaces influence the evolutionary childbirth process. After clinical confirmation on a large population, hypomobility of specified external pelvic diameters measured in shifting positions can become a screening tool to detect the contracted pelvis and prevent damage caused by dystocia and prolonged labor in women and newborns.

Safety and acceptance of "Vibwife", a new moving mattress to support mobilization during labor: Result of a clinical study

OBJECTIVE

To examine the safety and acceptance "Vibwife", a new moving mattress to support mobilization of pregnant women during labor.

DESIGN

The study was a prospective medical device clinical study without a control group. The study was designed in intervention phases, with safety evaluation by a safety review board after each intervention phase.

SETTING

The study took place at the University Hospital of Basel, Switzerland.

PARTICIPANTS

50 women were included with a low risk singleton pregnancy > 37^th weeks during the first stage of labor.

INTERVENTION

Evaluation of the safety and acceptance of women, midwives and physicians during the first stage of labor. The intervention was carried out in 3 phases. In the first phase five women in labor used the device for 10 minutes, the next 10 women for 20 minutes, and finally the next 35 women for 30 minutes.

MEASUREMENTS

Measurement included capturing Adverse Events (AEs) (including Adverse Device Effects (ADEs)), Serious Adverse Events (SAEs) and recording vital parameters before, during, and after intervention, as well as CTG before and after intervention. Acceptance by women, midwives and physicians was measured by questionnaires with a 4-point Likert scale and pain intensity by a discrete Visual Analogue Scale (VAS) from 0-10.

FINDINGS

No SAE occurred during the trial. A total of 32 AEs occurred in 25 women during the intervention or in the 30 minutes follow-up. The most frequently observed AEs were modification of blood pressure and CTG abnormalities. None of the 32 AEs led to sequels of any kind. The relationship between AEs occurrence and the use of the medical device was viewed as certain in 2 cases (6.2%), possible or likely in 8 cases (25%), and unlikely or unrelated in 22 cases (68, 7%). Overall, women, midwives and physicians reported high satisfaction with their use of the device.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

The medical device "Vibwife" was judged as safe for women. Acceptance among women and health personnel was good. Considering the potential benefits of mobilization during labor, this new medical device could be a very interesting adjunct to other obstetrical tools. Particularly, women whose mobility is restrained by epidural anesthesia while giving birth could be very suitable candidates. To answer the question of efficacy, a randomized-controlled trial is required.

Pelvic capacity in pregnant women, identified using magnetic resonance imaging

INTRODUCTION

Maternal pelvic capacity plays a major role during childbirth because the passage of the fetus through the bony birth canal enables vaginal birth. Maternal birthing position may influence pelvic capacity because upright positions optimize capacity, possibly due to free movement of the pelvic joints. Herein, pelvic capacity was assessed by comparing changes in pelvic dimensions across pregnancy and in three birthing positions.

MATERIAL AND METHODS

This diagnostic imaging study of 50 pregnant women was conducted at Aarhus University Hospital, Denmark. Pelvic measurements were obtained with 1.5 T magnetic resonance pelvimetry during gestational weeks 20 and 32, in three birthing positions: kneeling squat, semi-lithotomy and supine. Pelvic capacity was compared between gestational weeks and positions.

RESULTS

In all three positions there is an overall increase in pelvic capacity from gestational week 20-32 at both the pelvic inlet and outlet. Comparing pelvic capacity at gestational week 32 between the semi-lithotomy and supine positions revealed that the pelvic inlet was larger in the supine position, whereas the mean pelvic outlet was 0.2 cm (p < 0.001) larger in the semi-lithotomy position. Likewise, the pelvic inlet was larger in the supine than in the kneeling squat position. Shifting from supine to kneeling squat position increased the midplane and pelvic outlet dimensions by up to 1 cm (p < 0.001).

CONCLUSIONS

The finding herein of an increased pelvic capacity as the pregnancy progresses is novel. Further, the results indicate that the supine position is optimal for increasing pelvic inlet size, whereas the semi-lithotomy and kneeling squat positions are optimal for increasing mid- and outlet-pelvic capacities.

Asymmetric pelvis and term breech presentation: is planned vaginal delivery still a safe option?

PURPOSE

To evaluate the obstetrical prognosis of term breech delivery in case of asymmetric pelvis.

METHODS

An observational, comparative, retrospective, bi-centric study of 559 patients who had a computer tomography pelvimetry prior to delivery of a term breech presentation was conducted between August 2013 and August 2019. Patients with an attempted vaginal delivery were divided into two groups: a group of asymmetric pelvis (AP) when the difference between the lengths of both oblique diameters was ≥ 1 cm and a group of symmetric pelvis (SP) when the two oblique diameters differed by < 1 cm. The primary outcome was the rate of vaginal delivery. Secondary outcomes were a composite variable of neonatal and maternal morbidity and mortality.

RESULTS

Of the 370 patients who attempted a vaginal breech delivery, 8% (n = 29) had an AP and 92% (n = 341) had a SP. In the AP group, the vaginal delivery rate was higher (93% versus 78%, p = 0.05). There was no statistically significant difference in neonatal (3% versus 1% in the AP and SP groups, respectively, p = 0.4) and maternal (17% versus 23% in the AP and SP groups, respectively, p = 0.5) morbidity and mortality.

CONCLUSION

When a pelvimetry is performed before an attempt of vaginal breech delivery, a difference of less than two centimetres between both oblique diameters does not seem to reduce the rate of vaginal birth and is not an indication for an elective caesarean section.

Effect of the birthing position on its evolution from a biomechanical point of view

BACKGROUND AND OBJECTIVE

During vaginal delivery, several positions can be adopted by the mother to be more comfortable and to help the labor process. The positions chosen are very influenced by factors such as monitoring and intervention during the second stage of labor. However, there is limited evidence to support the most ideal birthing position. This work aims at contributing to a better knowledge associated with the widening of the pubic symphysis and the biomechanics of flexible and non-flexible sacrum positions that can be adopted during the second stage of labor, as well as their resulting pathophysiological consequences.

METHODS

A validated computational model composed by the pelvic floor muscles attached to the bones, and a fetus head was used to simulate vaginal deliveries. This model was modified to mimic two birthing positions: one that allows the free movement of the coccyx as in flexible sacrum positions and other in which this movement is more restricted as in non-flexible sacrum positions. The widening of the pubic symphysis was also considered to facilitate the passage of the fetus head.

RESULTS

The results obtained showed that, in non-flexible sacrum positions, where the coccyx movement is restricted, occur a rotation of 3.6° of the coccyx and a widening of 6 mm of the pubic symphysis. In contrast, in flexible sacrum positions, where the coccyx is free to move, occur a rotation of 15.7° of the coccyx and a widening of the pubic symphysis of 3 mm, appearing to be more beneficial for the mother's pelvis, but slightly higher stresses were detected in the pelvic floor muscles.

CONCLUSIONS

Globally, the results obtained allow to conclude that different birthing positions lead to changes in the female pelvic space, so certain positions can be adopted by the mother during the second stage of labor to reduce the risk of obstructed labor and the development of several dysfunctions. More specifically, flexible sacrum positions, such as kneeling, standing, squatting and sitting positions, are more beneficial for the bone structure of her pelvis as they allow a higher coccyx movement and lower widening of the pubic symphysis.

Dynamic External Pelvimetry Test in Third Trimester Pregnant Women: Shifting Positions Affect Pelvic Biomechanics and Create More Room in Obstetric Diameters

Dystocia in labor is still a clinical challenge. The "contracted pelvis" is the absence of pelvic mobility, which leads to fetal-pelvic disproportion, obstructed labor, and operative delivery. Maternal pelvis biomechanics studies by high technological techniques have shown that maternal shifting positions during pregnancy and labor can create more room in the pelvis for safe delivery. The external and internal pelvic diameters are related. The present study aims to evaluate the external obstetric pelvic diameters in shifting positions using a clinical technique suitable for daily practice in every clinical setting: the dynamic external pelvimetry test (DEP test). Seventy pregnant women were recruited, and the obstetric external pelvic diameters were measured, moving the position from kneeling standing to "hands-and-knees" to kneeling squat position. Results showed modification of the pelvic diameters in shifting position: the transverse and longitudinal diameters of Michaelis sacral area, the inter-tuberosities diameter, the bi-trochanters diameter, and the external conjugate widened; the bi-crestal iliac diameter, the bi-spinous iliac diameter, and the base of the Trillat's triangle decreased. The test showed good reproducibility and reliability. Linear correlations were found between diameters and between the range of motion of the diameters. The maternal pelvis is confirmed to modify the diameters changing its tridimensional shape. The pelvic inlet edge's inclination is inferred to be modified, facilitating the fetal descend. The pelvic outlet enlarged the transverse diameter, facilitating birth. The DEP test estimates the pelvic diameters' modification with postural changes, as magnetic resonance (MR) and computational biomechanics studies have demonstrated.

Estimating the Mobility of the Michaelis Sacral Rhombus in Pregnant Women

Pelvic mobility is the cornerstone of an adequate birth canal for safe childbirth, and midwives invite pregnant women to assume loading positions to facilitate delivery. Biomechanics asserts that pelvic space changes in shifting positions from erect to the squat position. The current standard practice in obstetrics and osteopathy provides a qualitative observational assessment of the dimension of Michaelis sacral rhombus in shifting positions; a previous report presented a clinical method and instrument to estimate the pelvic range of motion through finger contact on bone landmarks. The present study aims to match the measurement of the diameters of the sacral area of Michaelis from skin marks with the amount from bone landmarks. Methods estimate the sacral area from 100 pregnant women in the late trimester, considering the dimension of the diameters, the range of motion, and the patterns of mobility. Differences resulted in the methods: measuring the skin marks in shifting positions revealed a not significant difference between starting position and squat position. The measurements through the finger contact on the bone landmarks seem to be adequate to estimate pelvic mobility fulfilling the expectation from biomechanics literature.

A Postural Approach to the Pelvic Diameters of Obstetrics: The Dynamic External Pelvimetry Test

In recent years, there has been a renewed interest in internal and external pelvimetry, in relation to the diagnosis of dystocia from a "contracted pelvis." Dystocia is still one of the causes of maternal-fetal morbidity and mortality in the world. The main cause is the fetal-pelvic disproportion, of which mechanical dystocia and contracted pelvis are most probably involved. Clinical pelvimetry was the diagnostic method of "contracted pelvis" and still seems to have its place in the clinical obstetric routine. Studies have been conducted in order to measure anatomical diameters and correlate them with operative or vaginal delivery. Some studies have been published regarding the diameters' variation with the shifting of the patient's posture. The positions used in the research for the analysis of changes in pelvis measurements are the same as those used for centuries to assist and promote childbirth.

This technical report is to define a method of measuring changes in classical pelvimetric external diameters in relation to the postural change of the subjects, taking into consideration the needs of the operators, the postural difficulties of pregnant women and the evidence acquired from instrumental research. It aims to propose a dynamic postural method suited to daily practice, according to the directives and principles of the classical external obstetric pelvimetry.

Impact of continuous electronic fetal monitoring on birth outcomes in low-risk pregnancies

BACKGROUND

Continuous electronic fetal monitoring (CEFM) is a standard of hospital care during the intrapartum period. We investigated its use on childbirth outcomes in low-risk pregnancies, and examined whether outcomes differed by gestational age within a term pregnancy.

METHODS

A retrospective secondary data analysis using birth registry data from two diverse northeastern US states from 1992 to 2014. Chi-square test and the Fisher exact tests were used to examine associations between CEFM and childbirth outcomes. Multivariable Poisson regression models were used to estimate risk ratios of childbirth outcomes related to CEFM use, adjusting for potential confounders.

RESULTS

Use of CEFM was independently associated with a 10% (State 1) and 40% (State 2) increased risk for primary cesarean delivery and an increased risk for assisted vaginal births (14% and 24%, respectively) after adjustment for confounders. CEFM use was not associated with reduced risk for infant mortality (neonatal mortality, 0-27 days, and post-neonatal mortality, 28-364 days) in term births (37-41 weeks' gestation). After stratifying term pregnancies into early term, full term, and late term, use of CEFM was associated with reduced risk for neonatal mortality in early-term births (37 0/7 weeks' to 38 6/7 weeks' gestation) in State 2 (RR 0.44 [95% CI 0.21-0.92]), but not in State 1. There was no association between CEFM use and infant mortality (neonatal and post-neonatal) in full-term or late-term births.

CONCLUSIONS

The study results do not support universal use of CEFM in pregnancies that are low-risk and at term.

The Association of Variations in Hip and Pelvic Geometry With Pregnancy-Related Sacroiliac Joint Pain Based on a Longitudinal Analysis

STUDY DESIGN

Cross-sectional study using radiological measurements and longitudinal data analysis.

OBJECTIVE

We aim to explore hip/pelvic geometry on anteroposterior radiographs and examine if such parameters are associated with clinical symptoms.

SUMMARY OF BACKGROUND DATA

Pregnancy-related sacroiliac joint pain is a common disease and is responsible to the disability of daily activities. The etiology is likely to be correlated with the biomechanical factors which are determined by trunk load and hip/pelvic geometry. Previous studies have already found the association between symptoms and weight increase during pregnancy. However, the relationship between bony anatomy and pregnancy-related sacroiliac joint pain remains unknown.

METHODS

In total, 72 women were included in the final analysis. In pregnant women with self-reported sacroiliac joint pain, pain scores at 12, 24, 30, and 36 weeks of pregnancy were recorded and included in a mixed-effect linear regression model as dependent variables. The radiological measurements were included as independent variables. Furthermore, to investigate the relationship between hip/pelvic geometry and the activity-specific nociceptive phenomenon, the radiological measurements between patients with and without activity-induced pain were compared using a binominal logistic regression model.

RESULTS

The relative bilateral is chial tuberosity distance (betta coefficient: 0.078; P = 0.015) and the relative bilateral femoral head length (betta coefficient: 0.011; P = 0.028) showed significant interactions with the slope of pain scores. Moreover, women whose pain exacerbate during prolonged walking had a higher odds in hip/pelvic geometry of the bilateral ischial tuberosity distance (odds ratio [OR]: 1.12; P = 0.050) and the bilateral femoral head length (OR: 1.16; P = 0.076) with approximately significant P-value.

CONCLUSION

These data indicate hip/pelvic anatomical variations are associated with the degree of pain increasing and the activity-specific pain during pregnancy, which may help to have further understanding on the biomechanical factor in developing pregnancy-related sacroiliac joint pain.

LEVEL OF EVIDENCE

3.

Determining loads acting on the pelvis in upright and recumbent birthing positions: A case study

BACKGROUND

The biomechanics of mothers' birthing positions and their impact on maternal and newborn health outcomes are poorly understood. Our objectives were to determine the loads applied to the female pelvis during dynamic movement that may occur during childbirth; findings are intended to inform clinical understanding and further research on birth positioning mechanics.

METHODS

An optical motion capture system and force platforms were used to collect upright and supine movement data from two pregnant and three non-pregnant participants. Using an inverse dynamics approach, normalized three-dimensional hip and sagittal plane lumbosacral joint moments were estimated during squatting, all-fours, and supine activities.

FINDINGS

During squatting, peak hip abduction moments were greater for our pregnant (compared with non-pregnant) participants and lumbosacral extension moments substantially exceeded those during walking. The all-fours activity, conversely, generated flexion moments at the L5/S1 joint throughout most of the cycle. In supine, the magnitude of the ground reaction force reached 100% body weight with legs and upper body raised (McRoberts' position); the centre of pressure remained cranial to the sacrum.

INTERPRETATION

Squatting generated appreciable moments at the hip and lumbosacral joints that could potentially affect pelvic motion during childbirth.

Dynamic 3T pelvic floor magnetic resonance imaging in women progressing from the nulligravid to the primiparous state

INTRODUCTION AND HYPOTHESIS

The objective was to prospectively characterize dynamic pelvic 3-Tesla magnetic resonance imaging (dp3T MRI) findings in nulligravida women and characterize changes 6 months after delivery in the same woman.

METHODS

In this prospective study, nulligravida women seeking assisted reproductive technology for pregnancy were recruited. After physical examination by Pelvic Organ Prolapse Quantification (POP-Q), Brink assessment and measures including the Pelvic Floor Distress Inventory-20 and Pelvic Floor Impact Questionnaire-7, pre-pregnancy dp3T MRI at rest, with strain, and evacuation were performed. Assessments were repeated ≥6 months postpartum. Analysis included Welch and paired t tests for continuous variables, Fisher's exact test for differences in categorical outcomes, and paired t tests for postpartum symptoms.

RESULTS

Nineteen subjects (mean ± SD age, 31 ± 5 years) completed baseline clinical and dp3T MRI studies, 15 delivered and 10 (30.5 ± 3 years) completed pre-pregnancy and post-delivery clinical and dp3T MRI assessments. There were no significant changes in scores of validated questionnaires (all p > 0.05) or on POP-Q measures post-delivery. Two (20%) subjects without pre-pregnancy levator tears had tears on MRI post-delivery. MRI measures of pelvic organ descent were increased post-delivery. Seventeen pelvic soft-tissue parameters increased by greater than 10% post-delivery, including 5 out of 70 (7.1%), 17 out of 110 (15.5%), and 50 out of 110 (45.5%) values exceeding thresholds at rest, strain, and evacuation respectively.

CONCLUSIONS

Dynamic pelvic 3T MRI detected levator tears and increased pelvic organ descent, which can be directly attributed to pregnancy and delivery.

Biocultural perspectives on maternal mortality and obstetrical death from the past to the present

Global efforts to improve maternal health are the fifth focus goal of the Millennium Development Goals adopted by the international community in 2000. While maternal mortality is an epidemic, and the death of a woman in childbirth is tragic, certain assumptions that frame the risk of death for reproductive aged women continue to hinge on the anthropological theory of the "obstetric dilemma." According to this theory, a cost of hominin selection to bipedalism is the reduction of the pelvic girdle; in tension with increasing encephalization, this reduction results in cephalopelvic disproportion, creating an assumed fragile relationship between a woman, her reproductive body, and the neonates she gives birth to. This theory, conceived in the 19th century, gained traction in the paleoanthropological literature in the mid-20th century. Supported by biomedical discourses, it was cited as the definitive reason for difficulties in human birth. Bioarchaeological research supported this narrative by utilizing demographic parameters that depict the death of young women from reproductive complications. But the roles of biomedical and cultural practices that place women at higher risk for morbidity and early mortality are often not considered. This review argues that reinforcing the obstetrical dilemma by framing reproductive complications as the direct result of evolutionary forces conceals the larger health disparities and risks that women face globally. The obstetrical dilemma theory shifts the focus away from other physiological and cultural components that have evolved in concert with bipedalism to ensure the safe delivery of mother and child. It also sets the stage for a framework of biological determinism and structural violence in which the reproductive aged female is a product of her pathologized reproductive body. But what puts reproductive aged women at risk for higher rates of morbidity and mortality goes far beyond the reproductive body. Moving beyond reproduction as the root causes of health inequalities reveals gendered-based oppression and inequality in health analyses. In this new model, maternal mortality can be seen as a sensitive indicator of inequality and social development, and can be explored for what it is telling us about women's health and lives. This article reviews the research in pelvic architecture and cephalopelvic relationships from the subfields of evolutionary biology, paleoanthropology, bioarchaeology, medical anthropology, and medicine, juxtaposing it with historical, ethnographic, and global maternal health analyses to offer a biocultural examination of maternal mortality and reproductive risk management. It reveals the structural violence against reproductive aged women inherent in the biomedical management of birth. By reframing birth as normal, not pathological, global health initiatives can consider new policies that focus on larger issues of disparity (e.g., poverty, lack of education, and poor nutrition) and support better health outcomes across the spectrum of life for women globally.

New MRI Criteria for Successful Vaginal Breech Delivery in Primiparae

Background

Even if lower vaginal delivery success rates and impaired neonatal short-term outcomes have been reported for primiparous women with breech presentation, vaginal breech delivery remains an option for carefully selected patients. Because Magnetic resonance imaging (MRI) pelvimetry can provide additional information on maternal pelvic morphology, we sought to identify new MRI parameters that predict successful vaginal breech delivery.

Methods

In this retrospective unicentre study, 240 primiparous women with breech presentation at term underwent MRI pelvimetry. For all patients vaginal delivery was planned, according to German guidelines and if the conjugata vera (CV) was ≥12 cm. The patients with uneventful vaginal deliveries and the patients who underwent a secondary caesarean section were compared according to pelvimetric parameters and outcomes. Regression analyses were performed.

Results

In the vaginal delivery group (n = 162, (67.5%)), the distance between the spinae ischiadicae (interspinous diameter, ISD) was significantly enlarged. The ISD significantly influenced the mode of delivery in the regression analyses. The CV did not significantly differ between the groups. The patients with successful vaginal deliveries were significantly younger than the patients who underwent caesarean section. In the receiver operating characteristic (ROC) analysis, the area under the curve (AUC) for ISD was 67.7% (p<0.001, 95% CI [0.303–0.642]) and was higher considering the mother’s age (AUC = 73.1%, p<0.001, 95% CI [0.662–0.800]). The neonatal short-term outcomes were comparable in both groups.

Conclusion

The additional use of ISD may predict successful vaginal breech delivery and may be superior to the CV, which is more commonly used.

Trial Registration

DRKS00009957

Birth position and obstetric anal sphincter injury: a population-based study of 113 000 spontaneous births

BACKGROUND

The association between birth position and obstetric anal sphincter injury (OASIS) in spontaneous vaginal deliveries is unclear.

METHODS

The study was based on the Stockholm-Gotland Obstetric Database (Sweden) from Jan 1(st) 2008 to Oct 22(nd) 2014 and included 113 279 singleton spontaneous vaginal births with no episiotomy. We studied risk of OASIS with respect to the following birth positions: a) sitting, b) lithotomy, c) lateral, d) standing on knees, e) birth seat, f) supine, g) squatting, h) standing and i) all fours. All analyses were stratified for parity. General linear models were used to calculate risk ratios (RR) adjusted for maternal, pregnancy and fetal characteristics.

RESULTS

The rates of OASIS among nulliparous women, parous women and women undergoing vaginal birth after a caesarean (VBAC) were 5.7%, 1.3% and 10.6%, respectively. The rates varied by birth position: from 3.7 to 7.1% in nulliparous women, 0.6% to 2.6% in parous women and 5.6% to 18.2% in women undergoing VBAC. Regardless of parity, the lowest rates were found among women giving birth in standing position and the highest rates among women birthing in the lithotomy position. Compared with sitting position, the lithotomy position involved an increased risk of OASIS among nulliparous (adjusted RR 1.17, 95% CI 1.06-1.29) and parous women (adjusted RR 1.66, 95% CI 1.35-2.05). Birth seat and squatting position involved an increased risk of OASIS among parous women (adjusted RR [95% CI] 1.36 [1.03-1.80] and 2.16 [1.15-4.07], respectively). Independent risk factors for OASIS were maternal age, head circumference ≥35 cm, birth weight ≥4000 g, length of gestation ≥ 40 weeks, prolonged second stage of labour, non-occiput anterior presentation and oxytocin augmentation.

CONCLUSIONS

Compared with sitting position, lateral position has a slightly protective effect in nulliparous women whilst an increased risk is noted among women in the lithotomy position, irrespective of parity. Squatting and birth seat position involve an increase in risk among parous women.

Does pregnancy and/or shifting positions create more room in a woman's pelvis?

OBJECTIVE

The purpose of this study was to assess the impact of different positions on pelvic diameters by comparing pregnant and nonpregnant women who assumed a dorsal supine and kneeling squat position.

STUDY DESIGN

In this cohort study from a tertiary referral center in Germany, we enrolled 50 pregnant women and 50 nonpregnant women. Pelvic measurements were obtained with obstetric magnetic resonance imaging pelvimetry with the use of a 1.5-T scanner. We compared measurements of the depth (anteroposterior (AP) and width (transverse diameters) of the pelvis between the 2 positions.

RESULTS

The most striking finding was a significant 0.9-1.9 cm increase (7-15%) in the average transverse diameters in the kneeling squat position in both pregnant and nonpregnant groups. The average bispinous diameter in the pregnant group increased from 12.6 cm ± 0.65 cm in the supine dorsal to 14.5 cm ± 0.64 cm (P < .0001) in the kneeling squat; in the nonpregnant group the increase was from 12 cm ± 0.76 cm to 13.9 cm ± 1.04 cm (P < .0001). The average bituberous diameter in the pregnant group increased from 13.6 cm ± 0.93 cm in the supine dorsal to 14.5 cm ± 0.83 cm (P < .0001) in the kneeling squat position; in the nonpregnant women the increase was from 12.6 cm ± 0.92 cm to 13.5 cm ± 0.88 cm (P < .0001).

CONCLUSION

A kneeling squat position significantly increases the bony transverse and anteroposterior dimension in the mid pelvic plane and the pelvic outlet. Because this indicates that pelvic diameters change when women change positions, the potential for facilitation of delivery of the fetal head suggests further research that will compare maternal delivery positions is warranted.

Physical therapy in the management of pelvic floor muscles hypertonia in a woman with hereditary spastic paraplegia

Background. Pelvic floor (PF) hypertonic disorders are a group of conditions that present with muscular hypertonia or spasticity, resulting in a diminished capacity to isolate, contract, and relax the PF. Their presentation includes voiding and sexual dysfunctions, pelvic pain, and constipation. Various factors are associated, such as complicated vaginal birth, muscular injury, scar tissue formation, and neuropathies. Study Design. The case of a single patient will be presented, together with the management strategies employed. Case Description. A woman with hereditary spastic paraparesis and a history of muscle spasticity and urinary and fecal complaints since childhood. She presented to this institution seeking treatment for pelvic pain, pain during intercourse, constipation, and micturition problems. A physical therapy protocol was developed, with the trial of several treatment modalities. Outcome. After some failed attempts, perineal and pelvic floor stretching proved to be very efficacious therapies for this patient's complaint, leading to improved pain during intercourse, constipation, pelvic pain, and urinary stream. Discussion. PF spasticity can lead to severe disability and interfere with daily basic functions, such as micturition and evacuation. Physical therapy plays an essential role in the management of these patients and can lead to significant improvement in quality of life.

The obstetric dilemma: an ancient game of Russian roulette, or a variable dilemma sensitive to ecology?

The difficult birth process of humans, often described as the "obstetric dilemma," is commonly assumed to reflect antagonistic selective pressures favoring neonatal encephalization and maternal bipedal locomotion. However, cephalo-pelvic disproportion is not exclusive to humans, and is present in some primate species of smaller body size. The fossil record indicates mosaic evolution of the obstetric dilemma, involving a number of different evolutionary processes, and it appears to have shifted in magnitude between Australopithecus, Pleistocene Homo, and recent human populations. Most attention to date has focused on its generic nature, rather than on its variability between populations. We re-evaluate the nature of the human obstetric dilemma using updated hominin and primate literature, and then consider the contribution of phenotypic plasticity to variability in its magnitude. Both maternal pelvic dimensions and fetal growth patterns are sensitive to ecological factors such as diet and the thermal environment. Neonatal head girth has low plasticity, whereas neonatal mass and maternal stature have higher plasticity. Secular trends in body size may therefore exacerbate or decrease the obstetric dilemma. The emergence of agriculture may have exacerbated the dilemma, by decreasing maternal stature and increasing neonatal growth and adiposity due to dietary shifts. Paleodemographic comparisons between foragers and agriculturalists suggest that foragers have considerably lower rates of perinatal mortality. In contemporary populations, maternal stature remains strongly associated with perinatal mortality in many populations. Long-term improvements in nutrition across future generations may relieve the dilemma, but in the meantime, variability in its magnitude is likely to persist.

Labour augmentation and fetal outcomes in relation to birth positions: a secondary analysis of an RCT evaluating birth seat births

OBJECTIVE

the aim of this study was to compare the use of synthetic oxytocin for augmentation, duration of labour and birth and infant outcomes in nulliparous women randomised to birth on a birth seat or any other position.

STUDY DESIGN

a randomised controlled trial in Sweden where 1002 women were randomised to birth on a birth seat (experimental group) or birth in any other position (control group). Data were collected between November 2006 and July 2009. The outcome measurements included synthetic oxytocin augmentation, duration of the second stage of labour and fetal outcome. Analysis was by intention to treat.

SETTING

southern Sweden.

FINDINGS

the main findings of this study were that women randomised to the experimental group had a statistically significant shorter second stage of labour than women randomised to the control group. There were no differences between the groups for use of synthetic oxytocin augmentation or for neonatal outcomes.

CONCLUSIONS

women allocated to the birth seat had a significantly shorter second stage of labour despite similar numbers of women subjected to synthetic oxytocin augmentation in the study groups. The adverse neonatal outcomes did not differ between groups. The birth seat can be suggested as non-medical intervention used to reduce duration of second stage labour and birth. The birth seat can be suggested as a non-medical intervention that may facilitate reduced duration of the second stage of labour. Furthermore it is recommended that caregivers, both midwives and midwifery students, should learn skills to assist women in using a variety of birth positions.

TRIAL REGISTRATION

unique Protocol ID: Dnr 2009/739 (register.clinicaltrials.gov).

Ancient Egyptian Women’s Health Care in Relation to Modern Women’s Health Care Practices: An Overview

This article will address ancient Egyptians’ knowledge of the childbirth cycle from preconception to postpartum and the similarities of these practices to modern knowledge and practice. From developing the first recorded pregnancy test to using the favorable position of squatting in labor, the ancient Egyptians exhibited a base of knowledge that more recent use of the scientific method has confirmed. Other practices, such as methods of contraception, can be seen as steps in the evolution of methods used today. Ancient Egyptians emphasized maternal nutrition during pregnancy and care of the newborn and mother immediately postpartum. Newborn assessment in ancient Egypt consisted of two parameters—cry and muscle tone—that exhibits a historical technique analogous to the modern Apgar score. Evidence also indicates that the ancient Egyptians devised strategies to suture perineal tears and manage other postpartum complications. In addition to practices related to pregnancy and childbirth, other contributions of these ancient people to medical practice and vocabulary were associated with general women’s health.

Re-examining authoritative knowledge in the design and content of a TBA training in India

Since the 1990s, the TBA training strategy in developing countries has been increasingly seen as ineffective and hence its funding was subsequently reallocated to providing skilled attendants during delivery. The ineffectiveness of training programmes is blamed on TBAs lower literacy, their inability to adapt knowledge from training and certain practices that may cause maternal and infant health problems. However most training impact assessments evaluate post-training TBA practices and do not assess the training strategy. There are serious deficiencies noted in information on TBA training strategy in developing countries. The design and content of the training is vital to the effectiveness of TBA training programmes. We draw on Jordan's concept of 'authoritative knowledge' to assess the extent to which there is a synthesis of both biomedical and locally practiced knowledge in the content and community involvement in the design of TBA a training programme in India.

FINDINGS

The implementation of the TBA training programme at the local level overlooks the significance of and need for a baseline study and needs assessment at the local community level from which to build a training programme that is apposite to the local mother's needs and that fits within their 'comfort zone' during an act that, for most, requires a forum in which issues of modesty can be addressed. There was also little scope for the training to be a two way process of learning between the health professionals and the TBAs with hands-on experience and knowledge. The evidence from this study shows that there is an overall 'authority' of biomedical over traditional knowledge in the planning and implementation process of the TBA training programme. Certain vital information was not covered in the training content including advice to delay bathing babies for at least six hours after birth, to refrain from applying oil on the infant, and to wash hands again before directly handling mother or infant. Information on complication management and hypothermia was not adequately covered in the local TBA training programme.

KEY CONCLUSIONS

The suggested improvements include the need to include a baseline study, appropriate selection criteria, improve information in the training manual to increase clarity of meaning, and to encourage beneficial traditional practices through training.

The Evidence for Physiologic Management of the Active Phase of the First Stage of Labor

The active phase of first stage labor is generally defined as the period between 3 cm to 4 cm to complete cervical dilatation, in the presence of regular uterine contractions. Most women will experience this portion of labor within hospital obstetric units, where care commonly features restriction to bed, electronic fetal monitoring, early treatment of "slow" labors, and few pain management options beyond epidurals and narcotics. However, the available evidence on appropriate care for healthy childbearing women favors activity in labor, intermittent auscultation, patience from caregivers, and nonpharmacologic methods of pain relief. This article reviews the evidence for care practices that support physiologic labor. Modifying intrapartum care to reflect current evidence will improve women's health, and will require a multilevel approach and consistent midwifery demonstration of the model.

Update on Nonpharmacologic Approaches to Relieve Labor Pain and Prevent Suffering

The control of labor pain and prevention of suffering are major concerns of clinicians and their clients. Nonpharmacologic approaches toward these goals are consistent with midwifery management and the choices of many women. We undertook a literature search of scientific articles cataloged in CINAHL, PUBMED, the Cochrane Library, and AMED databases relating to the effectiveness of 13 non-pharmacologic methods used to relieve pain and reduce suffering in labor. Suffering, which is different from pain, is not an outcome that is usually measured after childbirth. We assumed that suffering is unlikely if indicators of satisfaction were positive after childbirth. Adequate evidence of benefit in reducing pain exists for continuous labor support, baths, intradermal water blocks, and maternal movement and positioning. Acupuncture, massage, transcutaneous electrical nerve stimulation, and hypnosis are promising, but they require further study. The effectiveness of childbirth education, relaxation and breathing, heat and cold, acupressure, hypnosis, aromatherapy, music, and audioanalgesia are either inadequately studied or findings are too variable to draw conclusions on effectiveness. All the methods studied had evidence of widespread satisfaction among a majority of users.

MR systems for MRI-guided interventions

The field of MR imaging has grown from diagnosis via morphologic imaging to more sophisticated diagnosis via both physiologic and morphologic imaging and finally to the guidance and control of interventions. A wide variety of interventional procedures from open brain surgeries to noninvasive focused ultrasound ablations have been guided with MR and the differences between diagnostic and interventional MR imaging systems have motivated the creation of a new field within MR. This review discusses the various systems that research groups and vendors have designed to meet the requirements of interventional MR and suggest possible solutions to those requirements that have not yet been met. The common requirements created by MR imaging guidance of interventional procedures are reviewed and different imaging system designs will be independently considered. The motivation and history of the different designs are discussed and the ability of the designs to satisfy the requirements is analyzed.

Protection of obstetric dimensions in a small-bodied human sample

In human females, the bony pelvis must find a balance between being small (narrow) for efficient bipedal locomotion, and being large to accommodate a relatively large newborn. It has been shown that within a given population, taller/larger-bodied women have larger pelvic canals. This study investigates whether in a population where small body size is the norm, pelvic geometry (size and shape), on average, shows accommodation to protect the obstetric canal. Osteometric data were collected from the pelves, femora, and clavicles (body size indicators) of adult skeletons representing a range of adult body size. Samples include Holocene Later Stone Age (LSA) foragers from southern Africa (n = 28 females, 31 males), Portuguese from the Coimbra-identified skeletal collection (CISC) (n = 40 females, 40 males) and European-Americans from the Hamann-Todd osteological collection (H-T) (n = 40 females, 40 males). Patterns of sexual dimorphism are similar in the samples. Univariate and multivariate analyses of raw and Mosimann shape-variables indicate that compared to the CISC and H-T females, the LSA females have relatively large midplane and outlet canal planes (particularly posterior and A-P lengths). The LSA males also follow this pattern, although with absolutely smaller pelves in multivariate space. The CISC females, who have equally small stature, but larger body mass, do not show the same type of pelvic canal size and shape accommodation. The results suggest that adaptive allometric modeling in at least some small-bodied populations protects the obstetric canal. These findings support the use of population-specific attributes in the clinical evaluation of obstetric risk.

Magnetic resonance-based serial pelvimetry: do maternal pelvic dimensions change during pregnancy?

OBJECTIVE

The purpose of the study was to evaluate the stability of the maternal pelvis over the course of the third trimester and the puerperium.

STUDY DESIGN

Pregnant patients were recruited to undergo comparative magnetic resonance-based pelvimetry and fetal ultrasonography at 37 to 38 weeks of gestation. Most of the patients were recruited from a study of women who planned a trial of labor after a previous cesarean delivery for cephalopelvic disproportion. These results have been reported previously. Patients then underwent magnetic resonance-based pelvimetry within 3 days and at 3 months after delivery. Postdelivery analysis was used to answer the question: Do pelvic dimensions change after delivery?

RESULTS

Eighteen patients completed the study. Eleven of the patients underwent cesarean deliveries, of which 4 deliveries were before labor. Seven patients had successful vaginal births after their previous cesarean delivery. Statistical analysis of the 18 patients determined that pelvic measurements did not demonstrate change over the course the study.

CONCLUSION

Serial magnetic resonance-based pelvimetry showed relative stability of pelvic measurements through the course of pregnancy and delivery. If comparative pelvimetry is to be useful as an antepartum predictor of labor success, then it may be possible to obtain reliable pelvimetry in those patients anytime after delivery.

Reproduction concepts and practices in ancient Egypt mirrored by modern medicine

The treasured ancient papyri provide a glimpse into understanding of common concepts and practices in ancient Egypt. The Kahun gynecological papyrus and other texts unveil the traditions of reproduction, conception and delivery. This article addresses the rationale of beliefs and practices of that era. Frequently, the reason for common traditions exercised at the time is based on medical knowledge of female anatomy and physiology during pregnancy. Surprisingly some of the remedies commonly used in ancient Egypt were recently explored and found intriguing. This paper was aimed to look at the reflection of archaic practices and concepts of ancient Egypt by the modern mirror of evidence-based medicine.

Measurement error in computed tomography pelvimetry

Computed tomography pelvimetry is still used in clinical practice. We wished to quantify observer error in order to assess the level of confidence with which pelvic measurements can be described as adequate or inadequate. Anteroposterior inlet, anteroposterior outlet, transverse inlet and interspinous distances were measured from 11 CT pelvimetry examinations by five observers at one institution. Three CT pelvimetries were measured by five observers at a second institution. Intraobserver and interobserver variation was assessed using analysis of variance. Reliability of measurements was assessed using intraclass correlation coefficient. Combined error was calculated to determine 95% confidence limits for published minimum recommended pelvic measurements. The standard error of measurement, combining all sources, for measurement of the bony dimensions of the pelvis were: for anteroposterior inlet, 2.0 mm; anteroposterior outlet, 6.9 mm; transverse inlet, 1.3 mm; and interspinous distance, 2.1 mm. The 95% confidence interval around the recommended anteroposterior outlet of 100 mm was 88.5-111.3 mm. Observer variation in measurement of anteroposterior outlet is so large as to make the measurement of doubtful clinical utility.