Development and validation of a computational model for understanding the effects of an upright birthing position on the female pelvis

Factors associated with the occurrence of upright birth in Brazil

OBJECTIVE

To identify the factors associated with Upright Delivery (UD) performed in hospitals linked to the Rede Cegonha (RC) in Brazil.

METHODS

Cross-sectional study with 3,073 parturients who had vaginal delivery in 606 health facilities in Brazil, located in health regions with a regional action plan approved in the RC. Socioeconomic, demographic, and obstetric characteristics of the parturients, organizational and management aspects of maternity hospitals, and work processes in childbirth care were evaluated. The multivariate logistic regression model with a hierarchical approach was adjusted to identify the variables associated with UD (outcome), estimating Odds Ratios (OR) with a significance level of 5%.

RESULTS

Of the evaluated parturient, 6.7% gave birth in the vertical position. The following were associated with a greater chance of PPV: being black (OR=2.07); having 13 or more years of study (OR=3.20); giving birth in a high-risk hospital (OR=1.58); giving birth in PPP rooms (which assisted with labor, delivery, and puerperium in the same environment) in Obstetric Centers (OR=2.07) or in-hospital Normal Delivery Centers (OR=1.62); being assisted by an obstetrician nurse (OR=1.64) or by a midwife (OR=7.62) when compared to a doctor; receiving massage during labor and delivery (OR=1.89); using a stool (OR=4.16) and among women who did not ask for/not receive analgesia (OR=3.15).

CONCLUSION

The UD is an event related to racial aspects and the education of the parturient, being stimulated in health establishments where good practices of childbirth care are implemented, with adequate ambiance, and with multidisciplinary teams comprising midwives and obstetric nurses.

Fatores associados à ocorrência de parto em posição vertical no Brasil

RESUMO Objetivo: Identificar os fatores associados aos partos na posição vertical realizados em hospitais vinculados à Rede Cegonha no Brasil. Métodos: Estudo transversal com 3.073 parturientes que tiveram parto vaginal em 606 estabelecimentos de saúde no Brasil, localizados em regiões de saúde com plano de ação regional aprovado na Rede Cegonha. Foram avaliadas características socioeconômicas, demográficas e obstétricas das parturientes, aspectos organizacionais e de gestão das maternidades e processos de trabalho na atenção ao parto. Modelo de regressão logística multivariada com abordagem hierarquizada foi ajustado para identificar as variáveis associadas ao parto na posição vertical (desfecho), estimando-se odds ratio (OR) com nível de significância de 5%. Resultados: Do total de parturientes avaliadas, 6,7% das mulheres tiveram parto na posição vertical. Estiveram associados à maior chance de ocorrência do parto na posição vertical: ser preta (OR=2,07); ter 13 ou mais anos de estudo (OR=3,20); parir em hospital de alto risco (OR=1,58); parir em quartos PPP (que dispunham de assistência ao trabalho de parto, parto e puerpério no mesmo ambiente) em centros obstétricos (OR=2,07) ou em centros de parto normal intra-hospitalares (OR=1,62); ser assistida por enfermeiro obstetra (OR=1,64) ou por obstetriz (OR=7,62) quando comparado ao médico; receber massagem durante o trabalho de parto e parto (OR=1,91); utilizar banqueta (OR=4,35) e entre mulheres que não pediram/não receberem analgesia (OR=3,33). Conclusão: O parto na posição vertical é um evento relacionado a aspectos raciais e à escolaridade da parturiente, sendo estimulado em estabelecimentos de saúde onde estão implantadas boas práticas de assistência ao parto, com ambiência adequada e com equipes multiprofissionais contendo obstetriz e enfermeiro obstetra.

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.