![]() During the second stage of labor, the fetal head is mostly found in an oblique occiput anterior (OA) position. The most common pelvic type is gynecoid, which is considered the most favorable shape for fetal descent during the different cardinal movements of labor (engagement, descent, flexion, internal rotation, extension, external rotation). Four different pelvic types have been described ( Figure 1): gynecoid (41.4%), android (32.5%), anthropoid (23.5%), and platypelloid (2.6%). The size and shape of the pelvis play an important role in the second stage of labor. The maternal pelvis consists of the bony pelvis and surrounding soft tissue structures. In this chapter, we will review the evidence on optimal management of the second stage of labor, with a focus on achieving vaginal delivery without increasing maternal and neonatal morbidities and mortalities. This would be a similar concept to using Montevideo units for defining adequate uterine contractility during the first stage of labor. It would be reasonable to consider the cumulative length of time a patient is pushing, the number of pushes, and/or cumulative force generated as a clinical measurement to define the optimal length of the second stage and potentially change the trigger for diagnosis of second stage labor arrest. However, the actual onset and duration of the second stage can be inaccurately recorded as the very definition of the beginning relies on an arbitrary time point when the examiner finds the cervix to be completely dilated. Ĭurrently, the American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal-Fetal Medicine (SMFM) define second stage of labor arrest as at least 2 hours of pushing in multiparous women and at least 3 hours of pushing in nulliparous women, with longer durations for epidural use and fetal malposition if progress is being documented. Most of these cesarean deliveries were unscheduled due to labor arrest. One study showed the rate of cesarean delivery during the second stage of labor in obese patients was twice as high as that in leaner individuals, especially for those with a BMI ≥ 35 kg/m 2. Intrapartum care of obese women also presents challenges, including a higher rate of cesarean delivery and associated complications such as postoperative wound infections, thromboembolic events, postpartum hemorrhage, endometritis, and delayed wound healing. It increases the risk of hypertensive disorders, gestational diabetes, macrosomia, intrauterine growth restriction, and infections. Obesity, defined as a BMI ≥ 30 kg/m 2, poses unique challenges for obstetrical providers throughout pregnancy. In this chapter, we will focus on how obesity affects the duration of labor as the prevalence of obesity is rising among reproductive-aged individuals. ![]() Several factors can influence the length of the second stage, including parity, maternal body mass index (BMI), fetal weight, fetal presentation, fetal position, and the use of analgesia. The second stage of labor is defined as the time from complete dilation of the cervix to delivery of the fetus. ![]() Here, we will review the evidence to help optimize the management of the second stage. By redefining the criteria used to define second stage labor dystocia or arrest, we can ensure that patients are given an appropriate amount of time to generate the expulsive forces necessary for a safe vaginal delivery. Therefore, it would be reasonable to consider factors such as the cumulative duration of pushing and/or the number of pushes and/or cumulative force generated as clinical measurements to determine the optimal length of the second stage of labor. In other words, the specific point at which the second stage begins (complete dilation) is influenced by the frequency of examinations conducted during labor. The beginning of the second stage of labor is determined by an arbitrary parameter that depends on the timing intervals at which patients are examined. Second stage arrest is diagnosed based on a fixed time frame without consideration of the total amount of expulsive forces exerted. Second stage labor arrest may occur more commonly in patients with obesity, leading to a higher number of cesarean deliveries. Obesity is an epidemic worldwide with about half of the population being classified as overweight and obese.
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