Introduction
Over the past fifty 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 Cesarean delivery and mostly with repeat Cesareans, in 2015, the World Health Organization (WHO) has recommended a maximum CD rate of 10-15% (2).
The substantial decrease in trial of labor after Cesarean deliveries (TOLAC) is one of the leading causes of the growing number of CD. The decline of TOLAC is primarily due to increased number of reported complications such as uterine rupture, as well as other factors including maternal request and decreased breech and operative vaginal deliveries (1, 3, 4).
However, since 1970, more studies evaluated the benefits of TOLAC compared to Cesarean delivery. In 2010 the National Institutes of Health stated that TOLAC is a reasonable option for most pregnant women who had prior low transverse Cesarean delivery (5).
Today, amongst women who attempt TOLAC, the rate of successful vaginal birth after Cesarean delivery; (VBAC) is beyond 70% (6, 7). It is associated with a lower maternal mortality rate and less overall morbidity for mothers and babies compared to Cesarean delivery.
Nevertheless, counseling women regarding the success rate of TOLAC is cumbersome. Several factors, including: increased maternal BMI, need for labor induction or augmentation, prior emergency Cesarean and estimated fetal macrosomia ( weight larger than 4000 g) are associated with failed TOLAC which in turn may lead to a greater maternal and perinatal risk than elective CD (8). Moreover physicians take safety margins and although ultrasonographic estimation of fetal weight, larger than 90th percentile was not considered to be associated with greater risk for uterine rupture (9), TOLAC is considered relatively contraindicated for macrosomic fetuses. Estimated fetal weight of 4000g is being used to consider avoidance of TOLAC and this may not suffice. Fetuses who are estimated to weigh more than the 90th percentile for the gestational age but are less than 4000 g may impose a risk for TOLAC as well.
To the best of our knowledge, literature regarding maternal and neonatal morbidity after TOLAC for eLGA (≥ 90th percentile) fetuses is scarce, and there are no recommendations regarding the preferred mode of delivery for mothers with eLGA and a history of CD. The aim of this study was to evaluate obstetrical outcome of TOLAC in women with large estimation of fetal weight in comparison to women with fetal weight smaller than 90th percentile.