Introduction
In 2012, national guidelines were published in the United States with
the goal of reducing the first or “primary” cesarean
birth.1,2 These guidelines considered a broad range of
opportunities to reduce cesarean birth but focused predominantly on
strategies to reduce the rate of primary cesarean in labor
(“intrapartum cesarean”). The contribution of pre-labor cesarean,
cesarean without an attempt at labor or vaginal birth, has received much
less attention.
Recently Hehir et al.3 used US vital statistics birth
certificate data and the Robson 10-Group Classification
System4 to examine cesarean birth rates in the US
between 2005 and 2014. Cesareans identified in the birth certificate as
being performed without a trial of labor were assigned as “pre-labor”.
The study suggested pre-labor cesareans in singleton term cephalic
pregnancies with no history of cesarean constituted 27% of all
cesareans in the US. Additionally, studies in Ireland5and Australia6 identified increases in both repeat
cesarean and pre-labor cesarean in singleton term cephalic
nulliparas as contributing to an increase in the total cesarean rate
between 2005 and 2014.
The goal of our study was to evaluate the contribution of cesarean
performed without attempting vaginal birth to all cesareans, and to
cesareans within subgroups of the pregnant population. Additionally,
stimulated by the studies by Hehir et al.3, we wanted
to evaluate the rate and indications for cesarean without attempting
vaginal birth in singleton term cephalic pregnancies with no history of
cesarean.
Methods :
This retrospective cohort study included births of
23+0-42+6 weeks’ gestation at 15
hospitals (5 Level I, 4 Level II, and 6 Level III/IV) in the Pacific
Northwest of the US between January 1, 2017 and March 31, 2018.
Intra-partum transfers from other hospitals or planned community-based
birth settings were excluded.
The data for the study came from the Foundation for Health Care
Quality’s Obstetrical Care Outcomes Assessment Program (OB COAP), an
ongoing multicenter, clinician-led, perinatal quality collaborative that
has been previously described in detail.7 The program
collects data from the medical records of consecutive births> 20 weeks’ gestation at hospitals in urban,
suburban, and rural settings. Trained abstractors at each site enter the
data into a cloud-based database. Subsets of variables are also uploaded
electronically from electronic medical records at some sites. Data
undergo real-time data quality and validation checks, both at the site
and aggregate level. Ad hoc quality checks are also conducted on a
routine basis by OB COAP staff. Patients were not involved in the
study.
Cesareans performed without attempting vaginal birth in the OB COAP
database are defined as cesareans where “surgical delivery has been
previously planned (planned primary or repeat cesarean) or if [the]
patient presents with an immediate need to deliver surgically
(unexpected maternal or fetal compromise upon presentation)”. These
cesareans were assigned as “pre-labor”, although it is likely that
some of these women were in labor at the time of initial presentation to
hospital.
Characteristics of the study population were explored including
demographic, pre-pregnancy, and pregnancy characteristics, and hospital
level of neonatal care (I – III/IV). Fisher’s exact test was used to
test for association between demographic characteristics and whether
vaginal birth was attempted.
Births in the study population were then grouped using the Robson
10-Group Classification System,4 described in detail
on the World Health Organization website.8 The Robson
classification categorizes all births in the population into ten
mutually exclusive groups based on parity, type of labor (spontaneous or
induced), previous cesarean birth, presentation, plurality, and
gestational age at birth (term or preterm) (Table 1).
The contribution of each of the Robson classification groups to all
births in the study population, the cesarean birth rate in each group,
the contribution of cesareans in the group to all births (“absolute
contribution”), and the contribution of cesareans in the group to all
cesarean births (“relative contribution”), were calculated. In
addition, we calculated the percentage of cesareans in each Robson group
that were pre-labor cesareans. For multiple pregnancies, cesarean rates
were based on the birth of the presenting baby (Baby A). Births that
could not be assigned to a Robson group because of missing data were
categorized as “non-classifiable”. The rate of pre-labor cesarean in
the nulliparous term singleton vertex (NTSV) population (Robson groups
1, 2a, and 2b), the standardized metric for cesarean birth in nulliparas
in the US, was additionally examined.
The primary cesarean (first cesarean irrespective of parity) rate cannot
be calculated directly from the Robson classification because some of
the Robson groups (7, 8, 9 and 10) include patients with and without
previous cesarean births. As a result, we separately calculated the rate
of primary cesarean, the percentage of all births that were pre-labor
cesareans, and the percentage of all cesareans that were pre-labor in
women with no history of cesarean birth.
Indications for pre-labor cesareans in singleton term cephalic
pregnancies with no history of cesarean (Robson groups 2b and 4b) were
also examined. The “indication for cesarean” field in the OB COAP
database includes the primary indication for cesarean stated in the
surgeon’s operative note. If a patient had a cesarean planned but
presented in labor with or without ruptured membranes, data abstractors
were directed to enter the original indication for the planned cesarean
in the “indication for cesarean” field. The “indication for
cesarean” field includes 20 specific indications for cesarean birth and
the option to choose “Other” if the indication does not fall into one
of the specified indications. For cesareans that fall into the “Other”
category, the indication is entered into a separate free text field.
Indications (including those in the free text field) were assigned by
one of the study authors (VS) into groups including maternal medical
condition, concern for fetal status, placental or cord complication,
fetal abnormality, pre-eclampsia/gestational hypertension, maternal
request, suspected macrosomia, suspected cephalopelvic disproportion,
complication in previous pregnancy, previous uterine surgery, active
genital herpes, other, and not known.
Descriptive statistics were calculated using R version 3.4.2.