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imões
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.
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ssoc
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ed
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ras
2015; 61(3):196-202
routes. On the other hand, analyzing neonatal
morbidity and mortality, the authors were able to
identify more frequent respiratory complications
among those born by cesarean section (p<0.05).
6. Blanchette H, et al (
B
)
.
11
•
•
Design: concurrent observational longitudinal
study.
•
•
Population: prospective study over 4 years includ-
ing all births to women who underwent previous
cesarean delivery (n=1.481). Comparison was made
between those who chose to repeat cesarean section
(n=727) and the women who opted for TOL (n=754).
•
•
Outcome: maternal morbidity and mortality.
•
•
Results: regarding the occurrence of uterine rup-
ture, need for blood transfusion, and hysterectomy,
the authors found a higher frequency among wom-
en undergoing trial of labor. However, among these
women, the maternal mortality rate was lower com-
pared to those undergoing elective cesarean section.
7. Paterson CM, et al. (
B
)
.
12
•
•
Design: non-concurrent observational longitudi-
nal study.
•
•
Population: records of 1,059 women in singleton
labor and with a previous cesarean section.
•
•
Outcome: postnatal morbidity and mortality.
•
•
Results: 395 women underwent elective cesarean
section and 664 underwent trial of labor. 71% of
the women undergoing trial of labor gave birth by
vaginal delivery. In this study, higher maternal mor-
bidity (postnatal infection) was identified both in
patients undergoing elective cesarean delivery and
in those with cesarean section performed due to
failure to progress, compared to vaginal delivery.
8. Wen SW, et al. (
B
)
.
13
•
•
Design: non-concurrent observational longitudi-
nal study (1988 to 2000).
•
•
Population: records of 308,755 women with a his-
tory of previous cesarean section were reviewed.
•
•
Outcome: maternal morbidity and mortality.
•
•
Results: the authors found that the risk of uterine
rupture was higher among women undergoing tri-
al of labor compared to those undergoing elective
cesarean section (RR=2.59 with 95%CI: 2.31 to
2.91). Regarding the need for hysterectomy, there
was no significant difference between groups.
Analyzing the occurrence of postpartum infection
and need for blood transfusion, the authors found
a lower risk of these outcomes among women un-
dergoing trial of labor (RR=0.81 with 95%CI: 0.724
to 0.908, and RR=1.27 with 95%CI: 1.068 to 1.521).
9. McMahon MJ, et al. (
B
)
.
14
•
•
Design: non-concurrent observational longitudi-
nal study (1986 to 1992).
•
•
Population: records of 6,138 women with a histo-
ry of previous cesarean section were reviewed (un-
dergoing trial of labor [n=3,249] or elective cesar-
ean section [n=2,889]).
•
•
Outcome: maternal and neonatal morbidity and
mortality.
•
•
Results: the authors found that the risk of severe
complications including uterine rupture, hyster-
ectomy and need for surgical lesion was greater
among patients undergoing trial of labor com-
pared to those undergoing elective cesarean sec-
tion (RR=1.96 with 95%CI: 1.18 to 3.26). Regard-
ing minor complications (need for blood
transfusion, puerperal fever and surgical wound
infection), there was no significant difference be-
tween groups (RR=0.82 with 95%CI: 0.68 to 1.0).
Based on the analysis of Apgar scores, need for ad-
mission to neonatal intensive care unit and peri-
natal mortality, there was no difference between
groups.
D
iscussion
Based on the above, we have identified a lack of controlled
studies analyzing the best type of delivery in cases of cesar-
ean section in a previous pregnancy. Supported mainly by
observational studies, most of them retrospective, current
evidence analyzing the outcomes of maternal morbidity
and mortality related to the type of delivery in this clinical
context is fragile, especially on account of biases inherent
to this particular type of study (
B
)
.
6-14
Facts that contrib-
ute to the difficulty in finding definitive evidence about
the best type of delivery include: heterogeneity in terms of
methodology employed to measure the outcomes; distinct
characteristics of the women enrolled (body mass index,
age, race, obstetric history, gestational age) and their ba-
bies (especially with respect to birth weight); and different
study durations, from start to end of the intervention, plus
follow-up period (in which the conduction of labor in terms
of technologies and rates of trial of labor differed). This
creates difficulties to analyze the true magnitude of the
benefits and risks in cases of cesarean section in a previous
pregnancy, without clarifying the doubts about the real
superiority of elective cesarean section indication in these