MATERIALS AND METHODS
This article is about a prospective analysis, studied with 400 pregnant women during labor between 37 and 41 weeks, and vertex presentation. We performed this study, approved by the local ethics committee numbered 2011-KAEK-25 2019/07-17, at the Department of Obstetrics and Gynecology of the Bursa Yüksek İhtisas Education and Research Hospital, Bursa, Turkey. All participants had a confirmed estimated date of birth by first-trimester ultrasound, which correlated with their menstrual dates.
We considered two criteria accepted by the American College of Obstetricians and Gynaecologists (ACOG) and Royal College of Obstetricians and Gynaecologists (RCOG) for shoulder dystocia: 1- Failure of shoulder delivery after downward traction, 2- Deliveries requiring maneuvers in addition to gentle downward traction on the fetal head to effect delivery.
Nonvertex presentation, preterm labor, cesarean delivery history, multiple gestations, before oxytocin initiation, a nonreassuring fetal heart rate tracing, or chorioamnionitis, ablatio placenta were not included in this study population.
Macrosomia of fetus (>4500 gram), women with gestational diabetes, women of short stature (less than 150 cm), occiput posterior fetal position, and history of dystocia, which are risk factors for the conditions we mentioned, were also excluded from the study.
The digital cervical examination performed in the first stage, two-four hours intervals, and one-two hours in the second stage. The results were documented according to the hours and on a partogram in addition to these records. The time from 6 cm to 10 cm and the time from complete cervical dilation to fetal head’s expulsion recorded. Also, whether shoulder dystocia developed at each delivery and the type of birth was registered.
During labor, in the protracted active phase, we administered oxytocin if not already started. However, women with labor arrest in the active phase and the second stage had gone cesarean delivery. Otherwise, the cesarean decision was made in cases with acute fetal distress during follow-up.
Participants had an ultrasound examination before 6 cm cervical dilation. Standard fetal biometry was measured, including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL), yielding a calculated estimated fetal weight (EFW) using the Hadlock formula.34 Fetal adipose tissue components consisted of the anterior abdominal wall (AAW), thigh (femur)(FWT), and upper arm (humerus) (HWT) adipose tissue. We defined the fetal adipose tissue composite as total adipose tissue (TATT). Total adipose tissue components consisted of the sum of the anterior abdominal wall, thigh, and arm adipose tissue thickness.
Fetal AAW measurement obtained at the abdominal circumference view, a plane where the junction of the right and left fetal portal vein and stomach seen. The image included fetal skin and subcutaneous tissue (Figure-1). Calipers were at the echogenic area between the outer skin edge and inner margin of the anterior abdominal wall. We calculated the anterior abdominal wall thickness (AAWT) as the thickness of this echogenic rim was measured at a point nearly 2 cm lateral to the umbilical cord insertion. Three measurements were obtained, and the mean value was recorded.
We obtained a standard image of the FL and HL, measuring fetal thigh and arm adiposity. The calipers placed between the bones’ outer face and the skin’s outer face in the midline. Then, another measurement was taken from the bones’ outer edge to the inner fat surface, and the fetal adiposity was calculated by subtracting this from the first measurement (Figure-2)(Figure-3). Standard perinatal and obstetric data documented during the birth.
The study’s primary outcome was to investigate if fetal adiposity was associated with an increased risk of labor protraction or arrest. Secondary outcomes included the effects of fetal adiposity on an increased risk of unplanned intrapartum cesarean delivery, active phase, second stage durations, birth weight of baby, fetus’s biometrical parameters, and shoulder dystocia.