**4. Surgical complications**

*Recent Advances in Cesarean Delivery*

with increasing BMI class [5].

or bias towards cesarean delivery [5].

cesarean delivery in women with BMI ≥ 40 kg/m2

why we see more unplanned cesarean delivery in obese women.

may be due to individual counseling by obstetric providers [19].

BMI ≥30 kg/m2

**2. Incidence of cesarean delivery in obese women**

, 30–47% BMI ≥ 40 kg/m2

Estimates of primary cesarean delivery rates in obese patients undergoing trial of labor range from 23 to 49%, and increase with increasing maternal BMI (23–46%

The reason for the increased incidence of cesarean delivery in obese women is likely multifactorial, and includes higher chances of macrosomia – and hence labor dystocia, disordered and dysfunctional labor patterns, and provider level responses

The combination of obesity and macrosomia significantly increases the chance of cesarean delivery [6]. Both pre-pregnancy BMI category and gestational weight gain are independent contributors to the development of a large for gestational age or macrosomic infant [7–8]. Obese women tend to have higher gestational weight gain, despite stricter weight gain recommendations, and hence larger birth weight babies [7]. A large fetus, for obvious reasons, predisposes the mother to a protracted labor course and cephalopelvic disproportion leading to an indicated cesarean delivery. In addition, fear of shoulder dystocia and neonatal brachial plexus injury, which occurs more often at delivery of obese women even with lower fetal birth weight, may influence the decision to proceed with cesarean delivery [9]. Because of the chances of fetal macrosomia with advancing gestational age, a strategy of elective induction at term may help to reduce the chances of macrosomia, and hence cesarean delivery. Elective induction was not associated with an increased risk of

Obese women also have dysfunctional labor patterns [11]. Obese women are less likely to have spontaneous onset of labor, less likely to achieve vaginal birth following spontaneous labor, and have a higher chance of being exposed to oxytocin than non-obese women [12]. Obese women may require larger doses of oxytocin than their normal weight counterparts, especially when undergoing induction of labor [13]. The pathophysiology of the increased oxytocin requirements and protracted labor course is poorly understood, but may be due to decreased myometrial receptor expression, prostaglandin insensitivity, and impaired myocyte contractility [14]. The dysfunctional and apparently disrupted myometrial activity may contribute to

Provider factors also may contribute to the increase chance of cesarean delivery in obese women [15]. Because the decision-to-incision and decision-to-delivery time interval for emergency cesarean delivery is significantly higher in obese women, a recommendation of cesarean delivery may be made earlier, in order to allow adequate time for surgical preparation [16, 17]. The timing of intervention for non-reassuring fetal heart rate patterns likely contributes to increased unplanned cesarean delivery, as well as pre-labor cesarean deliveries [5, 18]. Obese women with prior cesarean delivery are more likely to decline trial of labor after cesarean, which

Despite the fact that cesarean delivery is performed more often in obese women, it is still a riskier mode of delivery. Planned cesarean delivery, even in super-obese

) does not reduce maternal or neonatal morbidity [1].

[10].

most common indications for cesarean delivery are labor arrest (61%) and nonreassuring fetal status (28%) [1]. Pre-labor primary cesarean delivery also increases

**3. Factors contributing to cesarean delivery in obese women**

, 45–49% BMI ≥ 50 kg/m2

) [1–5]. The

**68**

women (BMI ≥ 50 kg/m2

Important peri-operative complications of cesarean delivery in obese women include wound complications (infection, wound separation), thromboembolic events, and adverse neonatal complications. A history of three or more prior cesarean deliveries further increases the chance of complications such as transfusion, low 1 min Apgar score, and wound complications [20]. The timing of repeat cesarean – unscheduled or planned – may also increase surgical and neonatal risks, especially since obese women are more likely to develop pregnancy complications prompting unscheduled repeat cesarean delivery [21]. Other surgical risks, such as bowel, bladder, or ureteral injury, or broad ligament hematoma, appear to be comparably infrequent in obese and super obese women like in normal and overweight women [22]. Super obesity also increases the chance of maternal ICU admission and length of hospitalization, which is largely driven by maternal co-morbid conditions [23, 24].
