Which Foetal-Pelvic Variables Are Useful for Predicting Caesarean Section and Instrumental Assistance

Abstract

Objective: To assess the variables useful to predict caesarean delivery (CD) and instrumental assistance, through the analysis of a large number of foetal-pelvic variables, using discriminant analysis. Materials and Methods: One hundred and fourteen pregnant women were included in this single-centre prospective study. For each mother-foetus pair, 43 pelvic and 18 foetal variables were measured. Partial least squares-discriminant analysis was performed to identify foetal-pelvic variables that could statistically separate the 3 delivery modality groups: spontaneous vaginal delivery (SVD), CD, and instrument-assisted delivery (IAD). Results: For the SVD versus CD model, voluminous foetuses and women with a narrow pelvic inlet had a greater risk for requiring CD. The most efficient variables for discrimination were the transverse diameter and foetal weight. The antero-posterior inlet and obstetric conjugate were considered in this model, with the former being a useful variable but not the latter. For the SVD versus IAD model, the most important variables were the foetal variables, particularly the bi-parietal diameter. Women with a reduced antero-posterior outlet diameter and a narrow pubic arch were more at risk of requiring an IAD. Conclusion: The antero-posterior inlet was an efficient variable unlike the obstetric conjugate. The obstetric conjugate diameter should no longer be considered a useful variable in estimating the arrest of labour. Antero-posterior inlet diameter was a sagittal variable that should be taken into account. The comparison of sub-pubic angle and bi-parietal and antero-posterior outlet diameters was useful in identifying a risk of requiring instrumental assistance.

Which foetal pelvic variables are useful for predicting right-rotational or left-rotational birth?

“…Our results suggest no significant difference between these two groups. We show in a previous study [9] that fetal-pelvic relationship could explain delivery outcomes, and among them, instrumental assistance: big fetuses and women with a small antero-posterior outlet diameter, a large obstetric conjugate, and a narrow pubic arch were at a greater risk of requiring instrumental assistance. Table 2.…”

“…All 102 women had both epidural anaesthesia and a pelvic scan, i.e., radiological measurement of the parameters of the pelvis, before delivery. Foetopelvic data were from a previous study [9]. For each woman, we noted the foetal head orientation during the engagement and the explusion stage, maternal postures during the labour and expulsion, and the amount of ropivacaine during labour.…”

“…A total of 43 pelvic variables were considered (Figure 1). Measurements with a standard error of ≤ 4 mm are deemed accurate and those outside this range considered inaccurate [9,10]. The newborn measurements were performed during the postpartum period using anthropometric tools (a cephalometric compass, a tape mesure, and a newborn scale).…”

Change in Head Shape of Newborn Infants in the Week following Birth: Contributing Factors

“…Data were acquired from previous studies 10,11 where mother-neonate dyads were consecutively selected. The newborn infants studied were singletons of both sexes, born between 37 and 42 weeks of gestational age at St Joseph's Hospital (Marseille, France) from the March 29, 2011, to December 10, 2013.…”

“…The Consequences for the Fetal-Pelvic Analyses Recent studies are based on cephalometric measurement of neonates. 10,11 In these studies, cephalometric variables are compared with pelvic measurements to analyze the variability of the fetal-pelvic relationship and its consequences on clinical outcomes. Because the bitragion difference decreases and the head circumference increases during the first 3 days of life, these measurements could lead to misinterpretation of the fetal-pelvic relationship.…”