Trial of labor after cesarean delivery for estimated large for gestational age fetuses: A retrospective cohort study

Over the past 50 years, there has been a remarkable increase in the rate of cesarean deliveries (CD) [1]. In order to reduce maternal and neonatal morbidity and mortality associated with a cesarean delivery and mostly with repeat cesareans, the World Health Organization (WHO) in 1985 recommended a maximum CD performance rate of 10–15% [2]. In 2015, the WHO revised its position and stated that CD should be performed only when medically indicated, and did not mention the preferred rate [3]. The substantial decrease in trial of labor after cesarean (TOLAC) deliveries is one of the leading causes of the growing number of CD. This decline is primarily due to the increased number of reported complications such as uterine rupture, as well as other factors, i.e., maternal request and decreased breech and operative vaginal deliveries [1,4,5].

However, since 1970, studies began to evaluate the benefits of TOLAC compared to cesarean deliveries. In 2010, the National Institutes of Health declared that TOLAC is a reasonable option for most pregnant women who had experienced a low transverse cesarean delivery [6]. Today, amongst women who undergo TOLAC, the rate of successful vaginal births after a cesarean delivery (VBAC) is >70% [7].VBAC is associated with a lower maternal mortality rate and less overall morbidity for mothers and babies compared to cesarean delivery [6]. Nevertheless, counseling women as to the success rate of TOLAC is ambiguous. Several factors, including increased maternal body mass index (BMI), need for labor induction or augmentation, a prior emergency CD and estimated fetal macrosomia (weight >4000 g), are associated with a failed TOLAC, which in turn may lead to greater maternal and perinatal risk than an elective CD [8].

Although ultrasonographic estimation of fetal weight (EFW) ≥90th percentile is not associated with a greater risk for uterine rupture [9], TOLAC is considered relatively contraindicated for macrosomic fetuses. Hence, when an EFW of 4000 g is detected, TOLAC is usually avoided. Most of the literature regarding risks of LGA fetuses during labor as well as during TOLAC refers to macrosomic fetus, however, LGA babies born at early term carry a risk for shoulder dystocia similar to macrosomic fetuses, and thus may as well reduce success rate for TOLAC [10].

To the best of our knowledge, the literature regarding maternal and neonatal morbidity after TOLAC for estimated large for gestational age fetuses (eLGA) (≥90th percentile) fetuses is scarce, and as yet, no recommendations have been proposed as to the preferred mode of delivery for mothers with eLGA and a history of CD. The aim of this study was to evaluate the obstetrical outcome of TOLAC in women with an eLGA in comparison to women with a fetal weight <90th percentile.

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