Keywords
cesarean section - indication - associated factors
Palavras-chave
cesariana - indicação - fatores associados
Introduction
In recent years, the rapid increase in cesarean section rates without clear evidence
of concomitant decrease in maternal or neonatal morbidity or mortality raises significant
concern that cesarean delivery is overused.[1]
The global increase in the number of cesarean sections is accompanied by an increase
in maternal and neonatal morbidity and mortality. Some of the outcomes observed are
a higher risk of complications in childbirth, from an anesthetic point of view, since
analgesia is performed at the surgical level. As a surgical procedure, cesarean section
offers a higher risk of complications when compared with vaginal delivery, as well
as longer hospitalization and postpartum recovery time. Other complications related
to the surgical event include increased risk of surgical wound hematoma, cardiac events,
puerperal infection, and long-term complications of abdominal surgery such as adhesions
and incisional hernia formation.[1]
[2]
[3]
It is worth noting that an increased number of cesarean sections may also be related
to a higher risk of placenta accreta, intestinal injury, ureteral injury, need for
postoperative ventilation, hospitalization in the intensive care unit, hysterectomy,
and blood transfusion. In addition, most uterine ruptures are associated with an attempt
to labor after a previous cesarean section.[2]
[3]
Despite attempts to reduce the risk of these adverse outcomes, the current high rates
of cesarean deliveries are not accompanied by a reduction in maternal and neonatal
morbidity and mortality, forgetting the art and experience of vaginal delivery is
a serious challenge to the nature and training of future obstetricians. In an overview,
the journey of childbirth care from the 21st century onwards ends in increasing rates of cesarean sections around the world.[1]
[2]
[3]
Primary cesarean is considered to be performed in women who have never undergone this
procedure before. As our objective was to determine associated factors with primary
cesarean sections to provide data on future strategies to potentially reduce elective/nonessential
indications, we collected data corresponding to age, ethnicity, residence, body mass
index (BMI), gestational age at birth, number of fetuses, fetal presentation, cesarean
indications, and maternal comorbidities. In addition, since our hospital is a regional
reference center for high-risk pregnancies, we collected the city of residence of
the patients. The indications for cesarean sections were also analyzed, comparing
the two years observed in the present study in relation to the conditions mentioned
below in the methods section.
Methods
Our group designed a cross-sectional study with data (collected from medical records)
of all patients who underwent primary cesarean at a university hospital in southern
Brazil (Hospital de Clínicas de Porto Alegre [HCPA, in the Portuguese acronym, Porto
Alegre, RS, Brazil) in the years 2006 and 2018. The years 2006 and 2018 were chosen
because our database was already filled with information from these years, and because
we also had the objective of comparing the factors associated with the chance of primary
cesarean section in different years.
All patients who underwent primary cesarean at the HCPA in 2006 and 2018 were included
in the present study. Data were collected from the collection of data from the medical
records of these patients.
The indications for cesarean sections were analyzed, comparing the two years regarding
the following conditions: whether the indication was elective or urgent, noncephalic
presentations, multiple pregnancies, nonreassuring fetal condition, cephalopelvic
disproportion, failure in induction of labor, antepartum hemorrhage, placental abruption,
placenta previa, HIV-positive, fetal malformations, active herpes, and macrosomia.
Our project was approved by the Research Ethics Committee of the HCPA (Letter of Approval
number 2020/0672) and was also forwarded to and approved by Plataforma Brasil for
publication (CAAE 40587620.7.0000.5327).
All analyses were made using R v4.0.1 (R Foundation for Statistical Computing, Vienna,
Austria) and Rstudio v1.4.1717 (RStudio Team. RStudio: Integrated Development Environment
for R).
To analyze differences between both groups, the Fisher exact test or the chi-squared
test were used for qualitative variables and, for quantitative ones, the Mann-Whitney
test for independent samples (as the majority presented an asymmetrical distribution)
was used. For comparisons between proportions, the prevalence ratios (PRs) accompanied
by their confidence intervals (CIs) at 95% were expressed, with differences whose
CI did not contain the unit and whose two-sided p-value was below the 5% significance
level were considered significant.
To adjust for potential confounders, we used a propensity score matching through a
logistic regression model with covariates defined by theory and by those baseline
characteristics that presented statistical significance in comparison among groups.
To prevent violation of logistic regression assumptions, we categorized continuous
covariates (BMI, gestational week, and age).
Results
In 2006, there were a total of 3,919 births, 2,636 vaginal births, and 1,239 cesarean
sections. Among the total number of cesarean sections, the number of primary cesarean
sections was 771, composing one of the analysis groups of our study ([Table 1]).
Table 1
Births in 2006 and 2018
|
Year
|
Vaginal births
|
Cesarean sections
|
Primary Cesareans
|
Births
|
Number of pregnant women
|
|
2006
|
2.636
|
1.239
|
771
|
3.919
|
3.870
|
|
2018
|
2.181
|
1.334
|
722
|
3.567
|
3.507
|
In 2018, there were 3,567 births, with 2,181 of them by vaginal delivery and 1,334
by cesarean sections. The number of primary cesarean sections in 2018 was 722, making
up the other analysis group in our study. Pregnant women who underwent cesarean sections
were older and had more comorbidities in 2018 compared with 2006. Pregnant women grouped
in 2018 also had a higher BMI. These variables (age, morbidity presence, BMI), along
with blood type, gemelarity, and gestational week ([Table 2]) were used for propensity scores matching to adjust to these potential confounders.
After this matching, our sample comprised 862 patients divided equally into both groups.
Then, the epidemiological profile of pregnant women in these 2 years were compared.
We considered morbidity as the presence of common or uncommon diseases during pregnancy,
such as gestational diabetes mellitus (GDM) and pregestational diabetes mellitus,
systemic arterial hypertension, pre-eclampsia and eclampsia, cardiopathy, nephropathy,
hepatopathy, and thyroid disease.
Table 2
Baseline factors – frequencies by year
|
Year
|
p-value
|
|
2006 (771)
|
2018 (722)
|
|
Age (years old)
|
23.00 (19.00–29.00)
|
26.00 (22.00–32.00)
|
< 0.001
|
|
Age, categorical (years old) (%)
|
|
< 18
|
96 (12.5)
|
28 (3.9)
|
< 0.001
|
|
18–34
|
600 (77.8)
|
566 (78.4)
|
|
35–39
|
55 (7.1)
|
94 (13.0)
|
|
≥ 40
|
20 (2.6)
|
34 (4.7)
|
|
BMI (kg/m2)
|
29.20 (26.30–33.50)
|
31.60 (28.22–36.10)
|
< 0.001
|
|
BMI, categorical (%)
|
|
Eutrophic
|
93 (13.7)
|
44 (9.1)
|
< 0.001
|
|
Overweight
|
283 (41.6)
|
137 (28.4)
|
|
Obesity I
|
173 (25.4)
|
148 (30.7)
|
|
Obesity II or III
|
132 (19.4)
|
153 (31.7)
|
|
Gestational age at birth
(weeks)
|
39.00 (37.00–40.00)
|
39.00 (37.00–40.00)
|
0.05
|
|
Gestational age, categorical
|
|
Extremely premature
(< 28 weeks)
|
23 (3.0)
|
13 (1.8)
|
0.327
|
|
Premature
(28–36 weeks)
|
158 (20.5)
|
152 (21.1)
|
|
Term (≥ 37 weeks)
|
590 (76.5)
|
557 (77.1)
|
|
Number of fetuses (%)
|
|
Twin
|
26 (3.4)
|
42 (5.8)
|
0.03
|
|
Triplet
|
3 (0.4)
|
3 (0.4)
|
1.00
|
|
Blood type (%)
|
|
A
|
316 (42.0)
|
255 (35.3)
|
0.057
|
|
AB
|
31 (4.1)
|
28 (3.9)
|
|
B
|
82 (10.9)
|
83 (11.5)
|
|
O
|
324 (43.0)
|
356 (49.3)
|
|
Morbidity (%)
|
267 (34.6)
|
357 (49.4)
|
< 0.001
|
Abbreviation: BMI, body mass index.
Values are expressed either in absolute value and percentage or in median and interquartile
range.
When comparing both groups, there was a significant difference between the 2 years
in twin pregnancy rates, GDM, and thyroid disease even after the adjusted analysis
([Table 3]). It is important to emphasize that it was not possible to obtain the BMI data of
329 patients (22%) because the deliveries occurred at the time of admission, by emergency
cesarean. In contrast, after the adjusted analysis, there was no significance in the
two years for HIV-positive pregnant women and depression.
Table 3
Comparison of morbimorbidities matched by propensity scores
|
Year
|
|
2006 (431)
|
2018 (431)
|
PR
|
95%CI
|
p-value
|
|
Ethnicity, non-white (%)
|
87 (20.2)
|
102 (23.7)
|
1.10
|
0.95–1.29
|
0.20
|
|
Porto Alegre (%)
|
276 (64.0)
|
288 (66.8)
|
1.06
|
0.92–1.23
|
0.39
|
|
Systemic arterial hypertension (%)
|
45 (10.4)
|
44 (10.2)
|
0.99
|
0.79–1.23
|
0.91
|
|
Severe pre-eclampsia (%)
|
20 (4.6)
|
13 (3.0)
|
0.78
|
0,51–1.20
|
0.26
|
|
Mild pre-eclampsia (%)
|
29 (6.7)
|
24 (5.6)
|
0.90
|
0.66–1.22
|
0.50
|
|
Rh factor, + (%)
|
387 (89.8)
|
395 (91.6)
|
1.12
|
0,87–1.44
|
0.30
|
|
Eclampsia (%)
|
4 (0.9)
|
1 (0.2)
|
0,55
|
0.24–1.27
|
0.16
|
|
Musculoskeletal diseases (%)
|
6 (1.4)
|
7 (1.6)
|
1.08
|
0.65–1.79
|
0.77
|
|
HIV positive (%)
|
12 (2.8)
|
14 (3.2)
|
1.08
|
0.75–1.55
|
0.68
|
|
Hepatopathy (%)
|
10 (2.3)
|
7 (1.6)
|
0.82
|
0.46–1.45
|
0,50
|
|
Cardiopathy (%)
|
4 (0.9)
|
8 (1.9)
|
1.34
|
0.89–2.01
|
0.16
|
|
Thyroid diseases (%)
|
2 (0.5)
|
16 (3.7)
|
1.81
|
1.51–2.16
|
< 0.0001
|
|
Nephropathy (%)
|
15 (3.5)
|
17 (3.9)
|
1.07
|
0.76–1.49
|
0,71
|
|
Pregestational diabetes mellitus (%)
|
7 (1.6)
|
10 (2.3)
|
1.18
|
0.79–1.77
|
0.42
|
|
Gestational diabetes mellitus (%)
|
17 (3.9)
|
39 (9.0)
|
1.43
|
1.19–1.73
|
< 0.0001
|
|
Depression (%)
|
7 (1.6)
|
14 (3.2)
|
1.34
|
0.99–1.83
|
0.06
|
Abbreviations: CI, confidence interval; PR, prevalence ratio.
Frequencies are aseparated by year. Values are expressed either by absolute value
and percentage or by median and interquartile range. ⧪viral load > 1,000 copies/ml
or unknown.
There was no statistically significant difference in the percentage of indications
for elective and nonelective primary cesarean sections between the 2 years (p = 0.2; PR: 1.10; 95%CI: 0.93–1.30), even in the unadjusted analysis. Most of the
variables analyzed did not show statistically significant differences in the indications
of primary cesarean sections. However, there were significant differences in crude
analysis comparing the two groups regarding premature rupture of membranes, fetal
malformations, and antepartum hemorrhage. In these comparisons, there was also significance
after matching by propensity scores ([Table 4]).
Table 4
Indications for primary cesareans–frequencies by year
|
Year
|
|
2006 (431)
|
2018 (431)
|
PR
|
95%CI
|
p-value
|
|
Indication
|
|
|
|
|
|
|
Elective cesarean
|
113 (26.2)
|
98 (22.7)
|
1
|
−
|
0.25
|
|
Nonelective cesarean
|
318 (73.8)
|
333 (78.3)
|
1.10
|
0.93–1.30
|
|
|
Noncephalic presentation
|
62 (14.4)
|
70 (16.2)
|
1.07
|
0.89–1.28
|
0.43
|
|
Multiple pregnancy
(twin + triplet)
|
1 (0.2)
|
1 (0.2)
|
1
|
0.24–4.00
|
1
|
|
Nonreassuring fetal condition
|
110 (25.5)
|
119 (27.6)
|
1,05
|
0.91–1.22
|
0.48
|
|
Cephalopelvic disproportion
|
157 (36.4)
|
154 (35.7)
|
0,98
|
0.86–1.13
|
0.83
|
|
Induction labor failure &
|
36 (8.4)
|
49 (11.4)
|
1,17
|
0.96–1.43
|
0.11
|
|
Premature rupture of membranes
|
77 (17.9)
|
103 (23.9)
|
1.19
|
1.02–1.38
|
0.02
|
|
Antepartum hemorrhage
|
8 (1.9)
|
16 (3.7)
|
1,35
|
1.01–1.80
|
0.05
|
|
Placental abruption
|
10 (2.3)
|
11 (2.6)
|
1.05
|
0.69–1.59
|
0.82
|
|
Placenta previa
|
2 (0.5)
|
2 (0.5)
|
1,00
|
0.37–2.67
|
1.00
|
|
Fetal malformations
|
6 (1.4)
|
20 (4.6)
|
1,56
|
1.25–1.95
|
0,00
|
|
Active herpes
|
4 (0.9)
|
6 (1.4)
|
1,20
|
0.72–2.00
|
0,48
|
|
Macrosomia
|
42 (9.7)
|
44 (10.2)
|
1,03
|
0.82–1.28
|
0,82
|
Abbreviations: CI, confidence interval; PR, prevalence ratio.
Frequencies are separated by year. Values are expressed either by absolute value and
percentage or by median and interquartile range.
& with indication of interruption without labor or any obstetric indication that prevents
delivery.
Discussion
The World Health Organization (WHO) advocates that every effort should be made to
provide cesarean sections to women in need, rather than achieving a specific goal.
For low-risk conditions, cesarean delivery seems to pose more maternal risk than vaginal
delivery. Although the indications for cesarean deliveries are established, the choice
for cesarean deliveries has increased globally both in low-, middle- and high-income
countries. This trend, however, was not accompanied by significant maternal and perinatal
benefits. On the contrary, the increase in cesarean delivery rates was not associated
with any demonstrable improvement in maternal or neonatal morbidity or mortality.[3]
[4]
[5]
[6]
Advanced maternal age, defined as pregnancy in women > 35 years old, is associated
with a potential clinical risk of complications such as fetal growth restriction,
pre-eclampsia, placental abruption, preterm delivery, and stillbirth. In addition,
systematic reviews and meta-analyses have shown the association between advanced maternal
age and increased risk of cesarean delivery.[7]
[8] Our study also showed that advanced maternal age was associated with a greater number
of primary cesarean sections in 2018 compared with 2006.
Gestational diabetes mellitus confers an increased risk of serious complications during
pregnancy both for the mother and the child, including cesarean delivery, shoulder
dystocia, macrosomia, and neonatal hypoglycemia.[9] In other studies, pregnant women with GDM had overall cesarean rates of 35.3%. Simultaneously,
compared with nondiabetic pregnant women, the reported cesarean rate was 1.52 times
higher in patients with GDM.[10]
[11] In this sense, our findings are similar to what is found in the literature regarding
the greater number of pregnancies that evolved to cesarean delivery in women with
GDM. Even so, this increase may be partially explained by changes in diagnostic criteria
between the two years.[12]
Premature rupture of membranes, despite not being among the indications for primary
cesarean sections, showed a statistically significant increase when comparing the
years 2006 and 2018. We relate this fact to the possibility that other variables are
associated with the condition, such as nonreassuring fetal condition and induction
failure, among others that configure indication for primary cesarean.
Twin pregnancies were also more frequent in 2018 in the unadjusted analysis, and,
therefore, were used for matching. However, when added to the triplet pregnancies,
there was no statistically significant difference in the indications for cesarean
sections between the two years evaluated. In vitro fertilization (IVF) is a safe and
highly effective treatment for infertility.[13]
[14] However, risks of obstetric and perinatal morbidity, such as hypertensive disorders
of pregnancy, GDM, cesarean section, placenta accreta, premature delivery, and low
birthweight, have been associated with IVF. These adverse outcomes are largely due
to an increased risk of multiple pregnancies in IVF, as several perinatal complications
increase with multiple pregnancies, including fetal anomalies, pre-eclampsia, and
GDM.[13]
[14] We think that the increase in the number of twin pregnancies in 2018 is due, in
part, to the increase in assisted reproduction techniques.
According to Hannah et al.,[15] there is a consensus that planned cesarean delivery is better than planned vaginal
delivery for the delivery of the fetus at breech presentation, if the fetus is compromised,
if the fetus is large, or if it has a congenital anomaly that can cause a mechanical
problem in vaginal delivery. Also, these authors concluded that a planned cesarean
policy is substantially better for the single fetus at term breech presentation, with
the benefits being greatest in countries reporting lower perinatal mortality rates.[15] A planned cesarean policy is not associated with an increased risk of serious problems
for the mother in the 1st 6 weeks after delivery. However, some results show that a subsequent delivery after
a pelvic cesarean delivery is associated with an increase in maternal and child morbidity,
regardless of the type of the subsequent delivery.[15]
[16]
In recent years, in addition to the increase in the number of cesarean sections, there
is a trend toward an increase in the number of elective cesarean sections, many of
them occurring at the request of the mother. Despite this increase, some studies suggest
that maternal and neonatal morbidity and mortality would not be reduced.[17]
[18] Our hospital serves predominantly patients from the public health system following
strict guidelines and criteria for performing elective cesarean sections. This can
justify the findings of our study, which presented no difference between elective
and nonelective cesarean sections between 2006 and 2018.
In our study, there was no difference regarding abnormal fetal presentation as an
indication for cesarean sections in the two years evaluated.
Before matching, there was a difference in comorbidity presence between the years
of 2006 and 2018. After matching and including this variable, only thyroid disease
was more frequent in 2018 than in 2006. Thyroid disease may be related to the increasing
age of pregnant women, since there is an increase in the incidence of this disease
with age, among other factors.
In addition to the limitations intrinsic to a cross-sectional study, we can add the
loss of 22% of the given BMI, the fact that we were analyzing data from a tertiary
hospital, and a sample that was probably biased. As external validity, we considered
tertiary centers and centers in developing countries.
Conclusion
Known risk factors for adverse events during pregnancy have become more frequent,
including advanced maternal age, twin pregnancy, higher BMI, GDM, thyroid disease,
and premature rupture of membranes. The present work provides data to reinforce institutional
strategies for the prevention and proper management of morbidities in our hospital;
therefore, it could reduce complications during pregnancy, as well as indications
for primary cesarean sections.
