DISCUSSION
According to the World Health Organization, birth occurs spontaneously,
between 37 and 42 weeks of pregnancy in the vertex position and without
significant risks throughout labor progression.35Labor characterized by regular uterine contractions results in
progressive fetal descent, expulsion, and live birth. Labor
abnormalities are categorized as labor prolongation, labor protraction,
or labor arrest.
Dysfunctional labor, labor dystocia, protraction/arrest disorders are
quite common among women during labor, and almost 20 percent of all
labors result in live births.36 Labor progress
disorders are the most common reason for primary intrapartum cesarean
delivery.
Labor protraction and arrest situations are in relation to many
different risk factors. In 2004, Algovik M et al. has declared that
genetic predisposition about labor prolongation.37 In
another study, in 2012, the effect of pelvic floor muscle strength on
labor was investigated. Pelvic floor muscles were found more substantial
in the failed labor than normally progressive labor.38Maternal age is a risk factor for cesarean section depending on
prolonging labor.39 Maternal body mass index and
obesity was defined as a risk factor for labor prolongation in another
article.40 As emphasized in some publications in the
literature, the duration of the first and second stages of labor was
prolonged by the use of epidural analgesia.4142
The present study’s primary purpose was to determine the effect of fetal
adipose tissue components on labor progression by excluding other risk
factors that cause prolongation. We planned to see the effect of fetus
soft tissue components on the diagnosis of labor protraction or arrest.
In this context, in our study, the adipose tissue components
individually and as a total composite caused an extension in the active
phase and the second stage of labor.
Shoulder dystocia is rarely seen, with an incidence of 0.2% to 3.0% of
all vaginal deliveries. This wide range is associated with the
clinician’s definition of shoulder dystocia, differences in defining the
degree of reporting, and the study population.43Shoulder dystocia has been seen more frequently in pregnant women who
have delivered vaginally and have longer durations of
labor.4445 In a study published in 1998 and with 722
participants, it was recognized %24 shoulder
dystocia.33 In another article, the shoulder dystocia
rate detected 16 percent.32 In our study, we detected
%3.3 of shoulder dystocia in all deliveries. These shoulder dystocias
were mild, easily reduced, responded promptly to McRoberts’s maneuvers
alone, or combined with suprapubic pressure and did not result in
neonatal injury. Longer duration of labor has associated with increased
rates of cesarean delivery in the literature.4647
In a study performed with 4126 women in the second stage of labor, it
was a higher duration of the second stage of labor was associated with
uterine atony.48 According to another study, perineal
trauma, instrumental delivery, postpartum hemorrhage, and
chorioamnionitis may be higher in pregnant women who have prolonged
labor.17
As seen from the studies mentioned above, prolongation of labor presents
many fetal and maternal problems. The prediction of labor protraction or
arrest can be vital because it is necessary to determine new diagnosis
or screening methods. As in our study, the measurement of fetal fat
tissue components can be a supportive method in this regard.
Farah et al. studied ultrasonographic soft tissue measurements in
detecting fetal macrosomia, gestational diabetes, and growth restriction
of the fetus.49 Sood AK et al. found a significant
correlation between humerus soft tissue and fetal
weight.50 In another study detected that fetus soft
tissue measurement might help to investigate fetal
macrosomia.51 In 2003, a study showing the
relationship between fetus adipose tissue components and gestational
diabetes had published. According to this study mentioned, values of
fetus mid-arm, mid-thigh, subscapular and anterior abdominal fat mass
were more significant in the gestational diabetes pregnancies than
normal pregnant women.52
Higgins MF et al. studied with 335 diabetic pregnancy and found that
anterior abdominal wall thickness measure significantly correlated with
macrosomia in gestational diabetes mellitus.53 In
another study ,mid-thigh soft tissue thickness was measured and found
significantly correlated with abdominal circumference and baby birth
weight.54
Our study aimed to show the relationship of measurement of fetal soft
tissue components with active phase and second stage of labor duration,
risk of cesarean section, shoulder dystocia, birth weight, and fetal
biometric parameters. As shown, Table-2 fetus soft tissue components,
both individually and in total, are significantly and positively
correlated active phase and second stage duration, birth weight of baby,
risk of cesarean delivery, biparietal diameter, abdominal circumference,
femur length, and shoulder dystocia.
With the binary logistic regression analysis, we performed, we found
that fetal fat tissue components caused prolongation or arrest in labor
(Table-3). At the same time, these components increase the rate of
cesarean delivery.
Also, we determined cut-off values for each of these components by
performing roc analysis. In general, areas under the process
characteristic curve found high values and p values to be significant.
In cases where total adipose tissue components exceed 20-21 mm levels,
labor prolonged with high sensitivity and specificity, and the cesarean
delivery rate increased. In general, the adiposity of the anterior
abdominal wall tissue above 8.6 mm-9.0 mm increases labor arrest and the
going to the cesarean section (Table-4).
The results of this study show us that it may be a useful method to
measure fetus adipose tissue components for an ideal follow-up of labor.
Measuring these components can be considered in predicting the
prolongation of labor and problems that may develop accordingly.
However, it can give an idea of the measurement of fetal adipose tissue
components in terms of risk of going to the cesarean section and
shoulder dystocia during delivery.
Researches related to this problem are essential since prolonged labor,
as we mentioned above, may cause many neonatal and maternal problems.
A potential limitation of this study is about long-term follow-up. Our
study designed not to accurately reflect differences in clinical
outcomes such as Erb’s palsy at vaginal delivery or neonatal term
follow-up of babies. In some morbidities, infants with increased adipose
deposition may be at risk of suffering; however, given their infrequent
occurrence appreciating a significant difference would require a much
larger cohort.
Measurement of fetal fat tissue components is not a part of routine
biometric measurements. Our study could not evaluate and analyze the
relationship between adipose tissue components and biometric parameters
in detail. Perhaps these adipose tissue components prolong the labor
process or increase the cesarean section’s risk, as they affect
biometric parameters. Some studies in the literature indicate that these
components are associated with gestational diabetes and macrosomia. More
and more long-term studies are needed for this analysis.
In conclusion, our study determined that labor progress is longer with
increased adipose deposition of the fetus. Fetus soft tissue thickness
positively correlated with labor protraction and labor arrest.
Measurement of soft tissue components may help provide labor follow-up.
Our study showed that fetuses with increased adipose deposition were
more likely to require a cesarean delivery, shoulder dystocia, and
higher birth weight. Increased fetal adiposity may be predictive of the
need for unplanned cesarean delivery, estimating fetal weight, and birth
complications. It was perhaps the first study in the literature in terms
of the analysis of fetal adipose tissue components with the progression
of labor. The relationship of the parameters with the results of the
study was generally found to be highly significant, but these data
should be supported by more detailed studies with more patients.