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.