Risk factors for postpartum hemorrhage after vaginal delivery of twins.

Abstract

We examined vaginal deliveries of twins to identify factors most strongly associated with the increased risk of postpartum hemorrhage (estimated blood loss > or = 1,000 mL). We reviewed the obstetric records of all 171 twin vaginal deliveries at Japanese Red Cross Katsushika Maternity Hospital from January 2002 through August 2006. Of these deliveries, 41 (24%) were complicated by postopartum hemorrhage. Postpartum hemorrhage was significantly more likely in cases with gestational age > or = 39 weeks (odds ratio [OR], 3.47; 95% confidence interval [CI], 1.65-7.28), a combined birth weight of more than 5,500 g (OR, 2.53; 95% CI, 1.00-6.45), induction of labor (OR, 2.87; 95% CI, 1.38-5.98), oxytocin administration during labor (OR, 2.86; 95% CI, 1.27-6.48), or a duration of labor > or = 24 hours (OR, 2.55; 95% CI, 1.15-5.62). Postpartum hemorrhage is a frequent complication in twin pregnancies. Therefore, special attention should be given after birth to patients with induction of labor or intervened delivery especially at > or = 39 weeks gestation.

Full text

Page 1

414 J Nippon Med Sch 2007; 74 (6)
―Report on Experiments and Clinical Cases―
Risk Factors for Postpartum Hemorrhage after
Vaginal Delivery of Twins
Shunji Suzuki, Fumi Kikuchi, Nozomi Ouchi, Chiaki Nagayama,
Michiko Nakagawa, Yusuke Inde, Miwa Igarashi and Hidehiko Miyake
Department of Obstetrics and Gynecology, Japanese Red Cross Katsushika Maternity Hospital, Tokyo
Abstract
We examined vaginal deliveries of twins to identify factors most strongly associated with
the increased risk of postpartum hemorrhage (estimated blood loss ? 1,000 mL). We reviewed
the obstetric records of all 171 twin vaginal deliveries at Japanese Red Cross Katsushika
Maternity Hospital from January 2002 through August 2006. Of these deliveries, 41 (24%) were
complicated by postopartum hemorrhage. Postpartum hemorrhage was significantly more
likely in cases with gestational age ? 39 weeks (odds ratio [OR], 3.47; 95% confidence interval
[CI], 1.65―7.28), a combined birth weight of more than 5,500 g (OR, 2.53; 95% CI, 1.00―6.45),
induction of labor (OR, 2.87; 95% CI, 1.38―5.98), oxytocin administration during labor (OR, 2.86;
95% CI, 1.27―6.48), or a duration of labor ? 24 hours (OR, 2.55; 95% CI, 1.15―5.62). Postpartum
hemorrhage is a frequent complication in twin pregnancies. Therefore, special attention should
be given after birth to patients with induction of labor or intervened delivery especially at ?
39 weeks’ gestation.
(J Nippon Med Sch 2007; 74: 414―417)
Key words: twin pregnancy, postpartum hemorrhage, advanced gestational age, induction of
labor
Introduction
In deliveries of twins, overdistention of the uterus
may weaken the contraction and retraction of the
uterine muscles and increase the risk of postpartum
hemorrhage1. The average blood loss during vaginal
delivery of twins has been reported to be 935 mL
and is greater than that during delivery of a single
fetus2. Thus, both active management and careful
observation are needed during the third stage of
labor in twin pregancies. However, the potential risk
factors for postpartum hemorrhage in twin births
have not been thoroughly examined. In this case-
control study, we examined vaginal deliveries of
twins to identify the factors most strongly associated
with an increased risk of postpartum hemorrhage.
Materials and Methods
We reviewed the obstetric records of all twin
vaginal deliveries at Japanese Red Cross Katsushika
Maternity Hospital form
August 2006. Cases with cesarean section for one
January 2002through
Correspondence to Shunji Suzuki, MD, Department of Obstetrics and Gynecology, Japanese Red Cross Katsushika
Maternity Hospital, 5―11―12 Tateishi, Katsushika-ku, Tokyo 124―0012, Japan
E-mail: czg83542@mopera.ne.jp
Journal Website (http:? ? www.nms.ac.jp? jnms? )

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Postpartum Hemorrhage after Vaginal Twin Delivery
J Nippon Med Sch 2007; 74 (6) 415
twin only, with the death of one fetus, or with a
retained placenta were excluded from this analysis.
In our hospital, the guidelines for vaginal delivery of
twin pregnancy without severe complications are (1)
vertex presentation of the first twin, (2) gestational
age at delivery ? 33 weeks, and (3) estimated birth
weight of at least 1,500 g for each twin. During this
period, elective cesarean section was performed if
patients showed twin-twin transfusion syndrome
( polyhydramnion-oligohydramnion
monochorionic-monoamniotic twin pregnancies, or a
history of previous cesarean deliveries. Labor was
induced with informed consent in 75 patients (44%)
on the basis of the appropriate date of delivery in
multifetal pregnancies reported by Minakami et al.3
In our hospital, we do not administer epidural
anesthesia for vaginal deliveries. When arrest of
dilation or descent, according to Friedman, lasting 2
hours occurred during the active phase of labor,
oxytocin (intravenous administration at an initial
dosage of 1 to 2 mU? minute) or amniotomy were
used. Usually,theplacenta
controlled cord traction. In addition, all patients
received a rapid venous infusion of 5 U of oxytocin
in 500 mL of lactated Ringer’s solution following
placental deliveryto
hemorrhage.
Blood loss during vaginal delivery was calculated
by collecting and measuring the blood in collection
devices used specifically for vaginal birth and then
weighing sheets, drapes, and sponges after delivery.
Demographic information and the characteristics of
labor were extracted from patient charts. Severe
perineal laceration was defined as either third- or
fourth-degreelaceration.
defined by an Apgar score < 7 at 1 minute. In this
study,postpartumhemorrhage
estimated blood loss ? 1,000 mL based on a
previous large study by Magann et al.4.
Demographic information and the characteristics
of labor were extracted from patient charts. In this
study,potential riskfactors
hemorrhage in twin pregnancies were
according toprevious
hemorrhage in singleton pregnancies4―8: maternal
age; parity, chorionicity, gestational age at delivery,
sequence ) ,
was extractedby
prevent postpartum
Neonatalasphyxiawas
wasdefinedas
forpostpartum
selected
postpartumstudies of
presentation of the second twin, induction of labor,
intertwindelivery-time
placentas, and history of infertility, preeclampsia,
prematureruptureofmembranes,
delivery, perineal laceration, duration of labor, and
dystociaorpostpartum
pregnancies1,2,9.
interval,number of
instrumental
hemorrhageintwin
Statistical Analysis
Cases and controls were compared by means of
Student’s t-test for continuous variables, and χ2or
Fisher’s exact test for categorical variables. Odds
ratios (ORs) and 95% confidence intervals (CIs) were
also calculated. Differences with P < 0.05 were
consideredsignificant.Variables
multivariate model were those that on univariate
analysis had shown marginal significance (P < 0.3)
toward association with increased risk of postpartum
hemorrhage. Logistic regression was then performed
to identify the factors most strongly associated with
postpartum hemorrhage in a multivariate model.
usedinthe
Results
During
deliveries
postpartum blood loss in these deliveries was 675 ±
452 g. Postpartum hemorrhage (estimated blood loss
?
1,000 mL) was diagnosed in 41 (24%) of these
deliveries. In addition, 6 patients (4%) received
transfusions. The incidence
hemorrhage in twin pregnancies was significantly
higher than that in singleton vaginal deliveries
during this period (1.3%; 89 of 7,029 singleton
pregnancies, p < 0.001).
Variable studies, analyzed by the incidence of
postpartumhemorrhage,
continuous variables in Table 1 and as dichotomous
variables in Table 2. The incidence of postpartum
hemorrhage was significantly greater in cases with a
gestational age ? 39 weeks, a combined birth
weight of more than 5,500 g, induction of labor,
oxytocin administration during labor, or a duration
of labor ? 24 hours.
Using logistic regression, the best model identified
independent effects resulting from gestational age at
this
of
period,
twin
there
pregnancies.
were 171 vaginal
averageThe
ofpostpartum
are summarizedas

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S. Suzuki, et al
416 J Nippon Med Sch 2007; 74 (6)
T a b l e 1 An a l y s i s o f c o n t i n u o u s v a r i a b l e s b y t h e i n c i d e n c e o f p o s t p a r t u m
h e mo r r h a g e
P - v a l u e ( ＋ )
4 1
3 1 . 0 ±6 . 0
0 . 5 ±0 . 4
3 8 . 3 ±2 . 1
7 . 0 ±4 . 3
2 0 . 1 ±1 7
5 , 0 5 6 ±6 9 8
( － )
1 3 0
2 9 . 1 ±5 . 4
0 . 6 ±0 . 4
3 7 . 5 ±2 . 0
6 . 1 ±3 . 9
1 6 . 1 ±1 5
4 , 8 1 2 ±6 5 4
P o s t p a r t u m h e mo r r h a g e
N u mb e r
Ma t e r n a l a g e ( y e a r s )
P a r i t y
G e s t a t i o n a l a g e a t d e l i v e r y ( we e k s )
D u r a t i o n o f l a b o r ( h o u r s )
I n t e r t wi n t i me i n t e r v a l ( mi n u t e s )
C o mb i n e d n e o n a t a l b i r t h we i g h t ( g )
D a t a a r e p r e s e n t e d a s me a n ±S D .
0 . 0 5 8
0 . 1 6
0 . 0 2 9
0 . 2 1
0 . 1 5
0 . 0 4 1
T a b l e 2 An a l y s i s o f d i c h o t o mo u s v a r i a b l e s b y t h e i n c i d e n c e o f p o s t p a r t u m h e mo r r h a g e
P - v a l u e9 5 % C IC r u d e O R ( ＋ )
4 1
1 0 ( 2 4 %)
2 2 ( 5 4 %)
6 ( 1 5 %)
6 ( 1 5 %)
4 ( 1 0 %)
1 0 ( 2 4 %)
( － )
1 3 0
3 1 ( 2 4 %)
6 4 ( 4 9 %)
1 0 ( 8 %)
8 ( 6 %)
1 0 ( 8 %)
4 5 ( 3 5 %)
P o s t p a r t u m h e mo r r h a g e
N u mb e r
Ma t e r n a l a g e >
N u l l i p a r o u s
H i s t o r y o f i n f e r t i l i t y
H i s t o r y o f I V F
P r e e c l a mp s i a
Mo n o c h o r i o n i c t wi n s
G e s t a t i o n a l a g e a t d e l i v e r y
0 . 9 4
0 . 6 2
0 . 1 8
0 . 0 8 4
0 . 6 7
0 . 2 2
0 . 4 5
0 . 5 9
0 . 7 0
0 . 8 5
0 . 3 8
0 . 2 7
― 2 . 3 4
― 2 . 4 1
― 6 . 0 6
― 8 . 0 4
― 4 . 3 8
― 1 . 3 5
1 . 0 3
1 . 1 9
2 . 0 6
2 . 6 1
1 . 3 0
0 . 6 1
＿ 3 5 y e a r s
0 . 5 1
0 . 0 0 1
0 . 2 4
0 . 5 5
0 . 0 0 3
0 . 0 9 5
0 . 1 9
1 . 0 0
0 . 3 5
1 . 6 5
0 . 7 0
0 . 5 6
1 . 3 8
1 . 2 7
0 . 9 0
― 1 . 8 8
― 7 . 2 8
― 4 . 2 4
― 2 . 9 7
― 5 . 9 8
― 6 . 4 8
― 2 . 8 3
―
0 . 7 7
3 . 4 7
1 . 7 2
1 . 2 9
2 . 8 7
2 . 8 6
1 . 5 9
0
1 1 ( 2 7 %)
2 0 ( 4 9 %)
3 4 ( 8 3 %)
1 0 ( 2 4 %)
2 6 ( 6 3 %)
3 2 ( 7 8 %)
1 1 ( 2 7 %)
0 ( 0 %)
4 2 ( 3 2 %)
2 8 ( 2 2 %)
9 6 ( 7 3 %)
2 6 ( 2 0 %)
4 9 ( 3 8 %)
7 2 ( 5 5 %)
2 1 ( 1 6 %)
0 ( 0 %)
<
>
＿ 3 6 we e k s
＿ 3 9 we e k s
V e r t e x - v e r t e x p r e s e n t a t i o n
P R O M
I n d u c t i o n o f l a b o r
O x y t o c i n u s e d u r i n g l a b o r
V a c u u m/ f o r c e p s d e l i v e r y
S e v e r e p e r i n e a l l a c e r a t i o n
C o mb i n e d n e o n a t a l b i r t h we i g h t > 5 , 5 0 0 g
0 . 0 4 6
0 . 5 7
0 . 0 1 8
1 . 0 0
0 . 2 9
1 . 1 5
― 6 . 4 5
― 2 . 0 0
― 5 . 6 2
2 . 5 3
0 . 7 6
2 . 5 5
9 ( 2 2 %)
6 ( 1 5 %)
1 4 ( 3 4 %)
1 3 ( 1 0 %)
2 4 ( 1 8 %)
2 2 ( 1 7 %)
D u r a t i o n o f l a b o r < 3 h o u r s
>
＿ 2 4 h o u r s
I n t e r t wi n t i me i n t e r v a l > 3 0 mi n u t e s
0 . 2 9
0 . 2 4
0 . 6 8
0 . 3 2
― 3 . 7 0
― 1 . 3 3
1 . 5 8
0 . 6 6
1 0 ( 2 4 %)
2 1 ( 5 1 %)
2 2 ( 1 7 %)
8 0 ( 6 2 %) O n e p l a c e n t a
I V F , i n v i t r o f e r t i l i z a t i o n ; P R O M, p r e ma t u r e r u p t u r e o f t h e me mb r a n e .
T a b l e 3 F i n a l l o g i s t i c r e g r e s s i o n mo d e l
9 5 % C IAd j u s t e d O R V a r i a b l e s
G e s t a t i o n a l a g e a t d e l i v e r y
3 7
>
I n d u c t i o n o f l a b o r
N o i n d u c t i o n＊
I n d u c t i o n o f l a b o r
1 . 0
4 . 2 9
― 3 8 we e k s＊
＿ 3 9 we e k s1 . 7 7 ― 1 0 . 3 5
1 . 0
2 . 6 21 . 0 8 ― 6 . 3 6
＊R e f e r e n c e g r o u p
delivery ? 39 weeks and induction of labor (Table
3). In addition, the OR for postpartum hemorrhage
with both induction of labor and delivery at ? 39
weeks was 5.77 (95% CI, 2.28―14.58; P = 0.00021).

Page 4

Postpartum Hemorrhage after Vaginal Twin Delivery
J Nippon Med Sch 2007; 74 (6) 417
Discussion
Inthis study, theincidenceofpostpartum
hemorrhage of at least 1,000 mL during vaginal
delivery of twins was 18-fold higher than that during
a singleton delivery. Our findings support previous
studies showing that multifetal pregnancy itself is a
risk factor for postpartum hemorrhage1,4.
In singleton pregnancies, risk factors for severe
postpartumhemorrhage
uterine atony or injury of soft tissue5. Previously
reported risk factors for uterine atony include:
induction of labor, prolonged labor, retained placenta,
generalanesthesia,the
overdistention of the uterus due to multiparity, large
fetus, or hydramnion5―8. In this study, although we
could not examine the effects of retained placenta or
hydramnion, which is associated with twin-twin
transfusion syndrome, twin pregnancies that require
induction of labor or use of oxytocin or both or that
are complicated by prolonged labor or large fetuses
might be expected to cause a failure of uterine
contraction when labor ends. Thus, the present
results suggest that the mechanisms leading to
postpartum hemorrhage in twin pregnancies are
similar to those in singleton pregnancies associated
with uterine atony, such as large fetuses, induction
of labor, and prolonged labor.
In this study, gestational age of at least 39 weeks
was a risk factor for postpartum hemorrhage in twin
pregnancies. The most appropriate gestational age
for delivery of multifetal pregnancies, in terms of
fetal and neonatal mortality, is supposedly 37 to 38
weeks3. Intrauterine growth in twins stops after 39
weeks, and placental weight reaches a plateau after
37 weeks’ gestation10,11. The limitation of the maternal
supply line is suggested to contribute to these
growth patterns. Therefore, perinatal outcomes in
multifetalpregnancieshave
benefit from induction of labor at 37 to 38 weeks3,12.
In the present study, there were no significant
differences in neonatal prognostic variables between
canbe categorizedas
useofoxytocin,
beensuggested to
cases with and without postpartum hemorrhage.
However, our findings suggest that the appropriate
date of delivery in twin pregnancies is 37 to 38
weeks, in consideration of maternal outcomes.
Inconclusion,postpartum
frequentcomplication
Therefore, special attention should be given after
birth to patients who have received induction of
labor or intervened delivery especially at ? 39
weeks’ gestation.
hemorrhage
twin
isa
ofpregnancies.
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