Shoulder Dystocia
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Br J Obstet Gynaecol. 1996
Sep;103(9):868-72.
Risk factors and fetal outcome in cases of shoulder
dystocia compared with normal deliveries of a similar
birthweight.
Bahar AM.
Department of Obstetrics and Gynaecology, University of
Kuwait.
Objectives:
To compare risk factors and fetal morbidity
in deliveries complicated by shoulder dystocia with
deliveries of similar infant birthweights but not
complicated by shoulder dystocia.
Design:
A
retrospective case-controlled study.
Setting:
Kuwait
Maternity Hospital. PARTICIPANTS: Sixty-nine cases of
true shoulder dystocia and 138 controls matched for
exact infant's birthweight.
Methods:
Demographic data
and data regarding history of previous shoulder dystocia,
diabetes mellitus, labour course, method of delivery and
newborns' condition were collected from patients and
case notes following delivery. The mothers' height and
weight were measured. Oral glucose tolerance test were
performed on patients who were not known as diabetics.
The infants' head and chest circumferences and
bisacromial diameter were measured.
Results:
There were
no significant differences between cases and controls
when mean age, parity, height, weight and gestational
ages were compared. The cases demonstrated a higher
incidence of previous shoulder dystocia (P < 0.01),
diabetes mellitus (P < 0.001), use of oxytocin for
acceleration of labour (P < 0.01) and operative vaginal
deliveries (P < 0.01). Differences between cases and
controls in their newborn infants' head and chest
circumferences were not significant, but the newborns of
cases have a longer mean bisacromial diameter and a
shorter head circumference:bisacromial diameter ratio (P
< 0.001 and P < 0.001, respectively). Thirty-seven
infants (53.6%) from cases and two from controls (1.4%)
sustained birth injuries. There were two stillbirths
among the cases.
Conclusions:
Although fetal macrosomia
is the principal risk factor for shoulder dystocia,
other important risk factors include diabetes mellitus,
previous history of shoulder dystocia, prolonged labour,
delay in the second stage of labour and fetal shoulder
width which appear to be independent of fetal weight.