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.