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Systematic Review
Prevalence of placenta praevia by world region: a systematicreview and meta-analysis
Jenny A. Cresswell, Carine Ronsmans, Clara Calvert and Veronique Filippi
London School of Hygiene & Tropical Medicine, London, UK
Abstract objectives (i) To estimate the prevalence burden of placenta praevia in each world region, and
(ii) to investigate potential sources of heterogeneity.
methods Systematic review of the literature and random-effects meta-analysis. Potential sources of
heterogeneity were investigated using meta-regression.
results The overall prevalence of placenta praevia was 5.2 per 1000 pregnancies (95% CI: 4.5
5.9). However, there was evidence of regional variation (P = 0.0001); prevalence was highest among
Asian studies (12.2 per 1000 pregnancies; 95% CI: 9.515.2) and lower among studies from Europe
(3.6 per 1000 pregnancies; 95% CI: 2.84.6), North America (2.9 per 1000 pregnancies; 95% CI:
2.33.5) and Sub-Saharan Africa (2.7 per 1000 pregnancies; 95% CI: 0.311.0). The prevalence of
major placenta praevia was 4.3 per 1000 pregnancies (95% CI: 3.35.4).
conclusion The prevalence of placenta praevia is low at around 5 per 1000 pregnancies. There is
some evidence suggestive of regional variation in its prevalence, but it is not possible to determine
from existing data whether this is due to true ethnic differences or other unknown factor(s).
keywords placenta praevia, antepartum haemorrhage, systematic review, meta-analysis, maternal
health, reproductive health
IntroductionPlacenta praevia is a potentially severe obstetric compli-
cation where the placenta lies within the lower segment
of the uterus, presenting an obstruction to the cervix and
thus to delivery. Risk factors for placenta praevia include
those that increase the likelihood of uterine scar tissue
(including higher parity, prior caesarean delivery or prior
abortion) or multiple gestations (Ananth et al.1997; Faiz
& Ananth 2003; Gurol-Urganciet al. 2011).
A previous systematic review by Faiz and Ananth
(2003) of studies published between 1966 and 2000 calcu-
lated the prevalence of placenta praevia to be 4.0 per
1000 pregnancies; both the search strategy and evidence
synthesis of this review emphasised North American liter-ature. Our study, conducted as part of a larger project
aiming to quantify the global burden of maternal haemor-
rhage (Calvertet al.2012), updates these results and puts
particular emphasis on capturing and including studies
originating outside of the USA and high-income countries.
Placenta praevia can result in life-threatening maternal
complications such as haemorrhage and shock and in
adverse infant outcomes such as prematurity, stillbirth and
neonatal death (Craneet al.1999, 2000; Baharet al.
2009). National hospital surveillance data from the USAdemonstrate a case-fatality rate of 17.3 deaths per 100 000
White women with placenta praevia and 40.7 deaths per
100 000 among Black women (Tuckeret al.2007). The
case-fatality rate in low-income settings is likely to be con-
siderably higher due to reduced antenatal screening and
lack of quality emergency obstetric care. The primary
objective of this paper was to estimate the prevalence of
placenta praevia in each world region; the secondary objec-
tive was to investigate potential sources of heterogeneity.
Methods
Data sources & search strategy
This review was part of a larger study investigating the
prevalence of maternal haemorrhage and the causes of
haemorrhage (Calvertet al.2012). The databases EM-
BASE, Medline, Popline, CAB Abstracts, African Index
Medicus, Eastern Mediterranean Region Index Medicus,
Latin American and Caribbean Center on Health Sciences
Information, and Western Pacific Region Index Medicus
712 2013 John Wiley & Sons Ltd
Tropical Medicine and International Health doi:10.1111/tmi.12100
volume 18 no 6 pp 712724 june 2013
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were searched using thesaurus and free-text terms to iden-
tify literature published from 1 January 1990 onwards.
The initial search strategy identified studies published up
until 2009; the search was later updated in April 2012.
The search strategy included thesaurus and free-textterms relating to haemorrhage, placenta praevia and
bleeding. A particular effort was made to identify litera-
ture from low-income settings by searching the WHO
regional databases. The reference lists of eligible studies
were hand searched to identify further publications. The
full search strategy is available upon request.
Inclusion criteria
Studies were eligible for inclusion if they reported the
number of cases of placenta praevia, along with a suitable
denominator for the total number of deliveries or births in
the population, and the median year of the study was1990 onwards. To capture population-representative data,
facility-based studies were excluded if local or national (if
local data unavailable) skilled birth attendance was
97%) of heterogeneity was
observed for all and major cases, which remained even
after stratification by study characteristic (Table 1). Inthe meta-regression (Table 2), the only study characteris-
tic with a significant effect on prevalence of all cases of
placenta praevia was geographic region (P = 0.0001).
Although region could explain around half of the
between-study variance, there was still a very high level
of residual heterogeneity after accounting for region
(98.5%).
Discussion
Our results show that the prevalence of placenta praevia
was around 5.2 cases per 1000 pregnancies (95%
CI: 4.5
5.9); the prevalence of major placenta praeviawas 4.3 cases per 1000 pregnancies (95% CI: 3.35.4).
Heterogeneity was very high, even after stratification on
study characteristics.
Geographic region was the only study characteristic
with a significant influence on prevalence. Prevalence was
highest among Asian studies (12.2 per 1000) and lower
among studies from Europe (3.6 per 1000), North Amer-
ica (2.9 per 1000) and Sub-Saharan Africa (2.7 per
2013 John Wiley & Sons Ltd 713
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J. A. Cresswell et al. Placenta praevia by world region
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1000). This could plausibly be due to true geographic or
ethnic differences between populations; several previous
studies have found the prevalence of placenta praevia to
vary between different ethnic groups (Sheineret al. 2001;
Ananthet al. 2003), including increased prevalence
among Asian women relative to White women (Shen
et al.2005). Any biological mechanism for this associa-
tion is poorly understood; however, ethnic differences in
prematurity rates or pelvic structure are possible explana-tions. It has been observed that normal gestational length
is shorter among Black and Asian women than among
White European women (Patel et al. 2004). However, it
is also possible that the apparent importance of the geo-
graphic region variable is a marker for other (unknown)
causes of heterogeneity between the studies. The majority
of studies identified in this review did not report the
distance between the placental edge and the cervical os;
subtle differences in national diagnostic protocols or con-
ventions may account in part for the observed regional
differences.
This study has investigated the prevalence of placenta
praevia in more diverse geographic locations than previ-
ously. However, there are a number of limitations.
Despite our best efforts, we retrieved a relatively small
number of studies from low- and middle-income coun-
tries. This partially reflects an imbalance in where studieson placenta praevia are conducted; however, this was
also partially due to our a prioridecision to only include
facility-based studies where skilled birth attendance was
>95%. We acknowledge that doing so has meant that we
have very few studies from some regions, such as Sub-
Saharan Africa, and that consequently our estimates can-
not be interpreted as representative of the entire region.
Nevertheless, we believe that our strategy was preferable
Original search on haemorrhage &causes of haemorrhage to
31stDecember 20091stApril 2012
MEDLINE, Embase, PoplineMEDLINE, Embase, Popline
LILIACS, CAB, EMRIM, AIM, WPRIMLILIACS, CAB, EMRIM, AIM, WPRIM
n= 13 205
n= 5121
n= 887
n= 136
n= 785
n= 12 182
n= 102
n= 36
n= 10
n= 12
Full text obtained
n= 68Full text obtained
Full text not available
Contained potentially relevantinformation on placenta praevia
Met inclusion criteria Met inclusion criteria
Inclusion in meta-analysis n= 48
Did not contain any information
related to placenta praevia
Exclusions:Skilled birth attendance
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Table
1
Random-effectsmeta-analysisofpooledprevalenceofplacentapraevia,stratifiedbycovariates
Characteristic
No.of
Studiesk
Pooledprevalenceper1000
pregnancies
Variationdue
toStudy
Heterogeneity(I2)
n
Prevalence
(95%
CI)
Allcasesofplacentapraevia
(marginal,partialorcomplete)
GBDRegion
Asia(Hendr
icksetal.1999;Yamadaetal.2005;Fujii
etal.2010;
Huangeta
l.2011;Jangetal.2011;Matsudaetal.2
011)
6
378
856
12.2
(9.5,15.2)
97.7%
Australasia(Oliveetal.2006;Lainetal.2008;McCormacketal.2008)
3
505
82
9.5
(4.8,15.7)
95.0%
Europe(Taipaleetal.1998;DSouza2000;Vettrainoetal.2001;
Grgicetal
.2004;Loveetal.2004;Romundstadeta
l.2006;Tuzovic
2006;Papinniemietal.2007;Tataetal.2007;Milos
evicetal.2009;
VazquezRodriguezetal.2010;Daskalakisetal.2011;Rosenbergetal.
2011)
13
146
1928
3.6
(2.8,4.6)
98.1%
LatinAmeri
ca&theCaribbeanCabrera(Hernandeze
tal.1999;
Faneiteetal.2001;Rivasetal.2001)
3
400
58
5.1
(2.5,8.7)
94.4%
NorthAfrica/MiddleEast(Ismail2001;Bhatetal.200
4;Baharetal.
2009;CelikAciogluetal.2010;Davoodetal.2010;
Alshamietal.2011)
6
995
44
6.4
(5.6,7.3)
57.8%
NorthAmer
ica(Ananthetal.2001;Francoisetal.2003;Koroukian2004;
Shenetal.
2005;Predanicetal.2007;Yangetal.2009;Aliyuetal.
2011a,b;E
ichelbergeretal.2011)
8
196
88426
2.9
(2.3,3.5)
99.5%
Sub-Saharan
Africa(Prualetal.2000;Buambo-Baman
gaetal.2004)
2
405
60
2.7
(0.3,11.0)
99.2%
WorldBank
Classification
Highincome(Taipaleetal.1998;Hendricksetal.199
9;DSouza2000;
Ananthet
al.2001;Vettrainoetal.2001;Francoisetal.2003;
Bhatetal.
2004;Koroukian2004;Loveetal.2004;Shenetal.2005;
Yamadaet
al.2005;Oliveetal.2006;Tuzovic2006;Romundstadetal.
2006;Papinniemietal.2007;Predanicetal.2007;Tataetal.2007;
McCormac
ketal.2008;Baharetal.2009;Yangetal.2009;Braggetal.
2010;Fujii
etal.2010;VazquezRodriguezetal.2010;Aliyuetal.
2011a,b;A
lshamietal.2011;Daskalakisetal.2011;Eichelbergeretal.
2011;Jang
etal.2011;Matsudaetal.2011;Rosenbergetal.2011)
30
215
59572
5.2
(4.4,6.0)
99.6%
Upper-middleincome(CabreraHernandezetal.1999;
Faneiteetal.2001;
Ismail2001;Rivasetal.2001;Grgicetal.2004;Milosevicetal.2009;
CelikAciogluetal.2010;Davoodetal.2010;Huangetal.2011)
9
149
822
5.8
(3.5,8.8)
97.8%
LowandLo
wer-middleincome(Prualetal.2000;Bua
mbo-Bamangaetal.
2004)
2
405
60
2.7
(0.3,11.0)
99.2%
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Table1
(continued)
Characteristic
No.of
Studiesk
Pooledprevalenceper1000
pregnancies
Variationdue
toStudy
Heterogeneity(I2)
n
Prevalence
(95%
CI)
Languageof
Publication
English(Taipaleetal.1998;Hendricksetal.1999;D
Souza2000;
Ananthet
al.2001;Ismail2001;Francoisetal.2003;Bhatetal.2004;
Koroukian
2004;Loveetal.2004;Shenetal.2005;Yamadaetal.2005;
Oliveetal
.2006;Romundstadetal.2006;Tuzovic2
006;Tataetal.
2007;Papinniemietal.2007;Predanicetal.2007;M
cCormacketal.
2008;Baharetal.2009;Yangetal.2009;Braggeta
l.2010;Davood
etal.2010
;Fujiietal.2010;Aliyuetal.2011a,b;Alshamietal.2011;
Daskalakis
etal.2011;Eichelbergeretal.2011;Huangetal.2011;
Jangetal.
2011;Matsudaetal.2011;Rosenbergetal.2011)
31
215
90322
5.5
(4.7,6.3)
99.6%
Non-English
(CabreraHernandezetal.1999;Prualet
al.2000;
Faneiteetal.2001;Rivasetal.2001;Vettrainoetal.2001;
Buambo-Bamangaetal.2004;Grgicetal.2004;Milosevicetal.2009;
CelikAciogluetal.2010;VazquezRodriguezetal.2
010)
10
159
622
4.2
(2.7,6.2)
96.5%
StudySetting
Facility-base
d(Taipaleetal.1998;CabreraHernandez
etal.1999;
Hendricks
etal.1999;DSouza2000;Faneiteetal.2
001;Ismail2001;
Rivasetal
.2001;Vettrainoetal.2001;Francoiseta
l.2003;
Bhatetal.
2004;Buambo-Bamangaetal.2004;Grgicetal.2004;
Loveetal.
2004;Yamadaetal.2005;Oliveetal.2006;Tuzovic2006;
Papinniemietal.2007;Predanicetal.2007;McCorm
acketal.2008;
Baharetal.2009;Milosevicetal.2009;CelikAciogluetal.2010;
Davoodet
al.2010;VazquezRodriguezetal.2010;Alshamietal.2011;
Daskalakis
etal.2011;Eichelbergeretal.2011;Jang
etal.2011)
28
547
893
5.2
(4.3,6.2)
95.9%
Population-based(Prualetal.2000;Ananthetal.2001;Koroukian2004;
Shenetal.
2005;Romundstadetal.2006;Tataetal.2007;
Yangetal.2009;Braggetal.2010;Fujiietal.2010;Aliyuetal.2011a,b;
Huangeta
l.2011;Matsudaetal.2011;Rosenberget
al.2011)
13
212
02060
5.0
(3.9,6.3)
99.8%
716 2013 John Wiley & Sons Ltd
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J. A. Cresswell et al. Placenta praevia by world region
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Table1
(continued)
Characteristic
No.of
Studiesk
Pooledprevalenceper1000
pregnancies
Variationdue
toStudy
Heterogeneity(I2)
n
Prevalence
(95%
CI)
Confirmation
ofPlacenta
Praevia
Diagnosis
Confirmeda
tdelivery(Taipaleetal.1998;CabreraHernandezetal.1999;
Hendricks
etal.1999;DSouza2000;Ananthetal.2
001;
Rivasetal
.2001;Francoisetal.2003;Buambo-Bamangaetal.2004;
Oliveetal
.2006;Romundstadetal.2006;Papinniem
ietal.2007;
Baharetal.2009)
13
161
7940
4.4
(3.2,5.7)
98.9%
Presentatla
stultrasoundpriortodelivery(Faneiteetal.2001;Ismail
2001;Bhatetal.2004;Loveetal.2004;Yamadaet
al.2005;
Tuzovic20
06;Predanicetal.2007;Daskalakisetal.
2011;
Eichelbergeretal.2011;Jangetal.2011;Matsudaetal.2011;
Rosenberg
etal.2011)
11
626
884
6.1
(3.7,9.1)
99.4%
Notreported(Prualetal.2000;Vettrainoetal.2001;
Grgicetal.2004;
Koroukian
2004;Shenetal.2005;Tataetal.2007;McCormacketal.
2008;Milo
sevicetal.2009;Yangetal.2009;Bragg
etal.2010;Celik
Aciogluet
al.2010;Davoodetal.2010;Fujiietal.2
010;Vazquez
Rodriguez
etal.2010;Aliyuetal.2011a,b;Alshamietal.2011;
Huangeta
l.2011)
17
195
05130
5.2
(4.3,6.2)
99.5%
Definitionof
denominator
Alldeliveries(CabreraHernandezetal.1999;Prualet
al.2000;
Faneiteetal.2001;Ismail2001;Rivasetal.2001;Vettrainoetal.2001;
Francoisetal.2003;Bhatetal.2004;Buambo-Bamangaetal.2004;
Grgicetal
.2004;Loveetal.2004;Shenetal.2005;
Yamadaetal.
2005;Oliveetal.2006;Tuzovic2006;Tataetal.20
07;Milosevicetal.
2009;Brag
getal.2010;CelikAciogluetal.2010;D
avoodetal.2010;
Rosenberg
etal.2011)
21
174
9648
4.6
(3.6,5.7)
98.5%
AllLiveBirths(Huangetal.2011)
1
212
34
17.5
(15.8,19.4)
Allsingleton
deliveries(Taipaleetal.1998;Hendricks
etal.1999;
DSouza2000;Romundstadetal.2006;Papinniemietal.2007;
Predanicetal.2007;McCormacketal.2008;Baharetal.2009;
Fujiietal.
2010;VazquezRodriguezetal.2010;Aliy
uetal.2011a,b;
Alshamiet
al.2011;Daskalakisetal.2011;Eichelbergeretal.2011;
Jangetal.
2011;Matsudaetal.2011)
16
260
7980
5.8
(4.0,8.0)
99.7%
AllSingletonLiveBirths(Ananthetal.2001;Koroukian2004;Yangetal.
2009)
3
173
71092
3.5
(2.4,4.8)
99.6%
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Table1
(continued)
Characteristic
No.of
Studiesk
Pooledprevalenceper1000
pregnancies
Variationdue
toStudy
Heterogeneity(I2)
n
Prevalence
(95%
CI)
Overall
41
21749954
5.2
(4.5,5.9)
99.5%
Majorplacentapraevia(partialorcomplete)
GBDRegion
Asia(Hendr
icksetal.1999;Hungetal.2007;Sumiga
maetal.2007;
Hasegawa
etal.2009;Jangetal.2011)
5
164
559
8.0
(6.0,10.3)
95.6%
Australasia
0
Europe(Taipaleetal.1998;DSouza2000;Beckeret
al.2001;Grgicetal.
2004;Loveetal.2004;Guarigliaetal.2006;Daskalakisetal.2011)
7
127
485
3.2
(1.9,4.8)
94.9%
LatinAmerica&theCaribbeanCabrera(Hernandeze
tal.1999;Faneite
etal.2001
;Rivasetal.2001)
3
400
58
3.3
(1.3,6.1)
93.8%
NorthAfrica/MiddleEast(Bhatetal.2004;Bahareta
l.2009)
2
514
94
4.1
(3.6,4.7)
0.0%
NorthAmer
ica(Craneetal.2000;Cleary-Goldmanet
al.2005;
Predanicetal.2007;Eichelbergeretal.2011)
4
166
458
3.0
(1.5,5.0)
97.1%
Sub-Saharan
Africa(Buambo-Bamangaetal.2004)
1
202
34
5.3
(4.4,6.4)
Worldbank
classification
Highincome(Taipaleetal.1998;Hendricksetal.199
9;Craneetal.
2000;DSo
uza2000;Beckeretal.2001;Bhatetal.2
004;Loveetal.
2004;Clea
ry-Goldmanetal.2005;Guarigliaetal.2006;Predanicetal.
2007;Sumigamaetal.2007;Baharetal.2009;Hasegawaetal.2009;
Daskalakis
etal.2011;Eichelbergeretal.2011;Jang
etal.2011)
16
463
284
4.3
(3.3,5.4)
96.3%
Upper-middleincome(CabreraHernandezetal.1999;
Faneiteetal.2001;
Rivasetal
.2001;Grgicetal.2004;Hungetal.2007
)
5
867
70
4.1
(1.1,8.7)
98.6%
LowandLo
wer-middleincome(Buambo-Bamangaet
al.2004)
1
202
34
5.3
(4.4,6.4)
Languageof
Publication
English(Taipaleetal.1998;Hendricksetal.1999;Cr
aneetal.2000;
DSouza2000;Beckeretal.2001;Bhatetal.2004;L
oveetal.2004;
Cleary-Goldmanetal.2005;Hungetal.2007;Preda
nicetal.2007;
Sumigama
etal.2007;Baharetal.2009;Hasegawaetal.2009;
Daskalakis
etal.2011;Eichelbergeretal.2011;Jang
etal.2011)
16
473
560
4.5
(3.3,6.0)
97.7%
Non-English
(CabreraHernandezetal.1999;Faneiteetal.2001;Rivas
etal.2001
;Buambo-Bamangaetal.2004;Grgiceta
l.2004;
Guarigliae
tal.2006)
6
967
28
3.6
(2.2,5.4)
94.2%
718 2013 John Wiley & Sons Ltd
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J. A. Cresswell et al. Placenta praevia by world region
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Table1
(continued)
Characteristic
No.of
Studiesk
Pooledprevalenceper1000
pregnancies
Variationdue
toStudy
Heterogeneity(I2)
n
Prevalence
(95%
CI)
StudySetting
Facility-base
d(Taipaleetal.1998;CabreraHernandez
etal.1999;
Hendricks
etal.1999;DSouza2000;Beckeretal.2001;Faneiteetal.
2001;Riva
setal.2001;Bhatetal.2004;Buambo-Bamangaetal.2004;
Grgicetal
.2004;Loveetal.2004;Cleary-Goldman
etal.2005;
Guarigliae
tal.2006;Hungetal.2007;Predaniceta
l.2007;Sumigama
etal.2007
;Baharetal.2009;Hasegawaetal.2009;
Daskalakisetal.
2011;Eichelbergeretal.2011;Jangetal.2011)
21
476
292
4.3
(3.3,5.5)
97.1%
Population-based(Craneetal.2000)
1
939
96
3.2
(2.9,3.6)
Confirmation
ofPlacenta
Praevia
Diagnosis
Confirmeda
tdelivery(Taipaleetal.1998;CabreraHernandezetal.1999;
Hendricks
etal.1999;Craneetal.2000;DSouza20
00;
Beckereta
l.2001;Rivasetal.2001;Buambo-Baman
gaetal.2004;
Cleary-Goldmanetal.2005;Guarigliaetal.2006;Baharetal.2009)
13
366
688
4.5
(3.2,6.0)
97.4%
Presentatla
stultrasoundpriortodelivery(Faneiteet
al.2001;
Bhatetal.
2004;Loveetal.2004;Predanicetal.2007;
Sumigama
etal.2007;Hasegawaetal.2009;Daskalakisetal.2011;
Eichelbergeretal.2011;Jangetal.2011)
8
194
590
4.4
(2.6,6.4)
97.2%
Notreported(Grgicetal.2004;Hungetal.2007)
1
901
0
1.3
(0.7,2.2)
Definitionof
denominator
Alldeliverie
s(CabreraHernandezetal.1999;Cranee
tal.2000;
Beckereta
l.2001;Faneiteetal.2001;Rivasetal.2001;
Bhatetal.
2004;Buambo-Bamangaetal.2004;Grgicetal.2004;
Loveetal.
2004;Guarigliaetal.2006;Sumigamaet
al.2007;
Hasegawa
etal.2009)
12
322
601
4.1
(3.0,5.3)
95.8%
Alllivebirths
0
Allsingleton
deliveries(Taipaleetal.1998;Hendricks
etal.1999;
DSouza2000;Cleary-Goldmanetal.2005;Hungeta
l.2007;
Predanicetal.2007;Baharetal.2009;Daskalakisetal.2011;
Eichelbergeretal.2011;Jangetal.2011)
10
247
687
4.6
(2.8,6.7)
98.1%
AllSingletonLiveBirths
0
Overall
22
570288
4.3
(3.3,5.4)
97.2%
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Table
2
Meta-regression
Studycharacteristic
OR
[95%
confidence
interval]
Testforc
ovariate
withKnapp-Hartung
modification
Proportion
ofbetween-study
varianceexplained
(AdjustedR2)
Residual
variation
duetostudy
heterogeneity
(ResidualI2)
Allcasesofplacentapraevia
(marginal,partialorcomplete)
GBDRegion
Asia
1.00
F
=
6.96;
P
=
0.00
01
50.4%
98.5%
Australasia
0.78
[0.361.68]
Eu
rope
0.29
[0.170.49]
La
tinAmerica&theCaribbean
0.42
[0.190.90]
NorthAfrica/MiddleEast
0.55
[0.301.03]
NorthAmerica
0.24
[0.130.42]
Su
b-SaharanAfrica
0.19
[0.080.46]
WorldBank
Classification
Highincome
1.00
F
=
1.32;
P
=
0.27
86
Upper-middleincome
1.13
[0.641.99]
Lo
wandLower-middleincome
0.44
[0.141.33]
Languageof
Publication
En
glish
1.00
F
=
0.89;
P
=
0.35
22
Non-English
0.77
[0.451.34]
StudySetting
Fa
cility-based
1.00
F
=
0.49;
P
=
0.48
89
Po
pulation-based
0.84
[0.511.39]
Confirmation
ofPlacenta
PraeviaDiagnosis
Confirmedatdelivery
1.00
F
=
0.56;
P
=
0.57
54
Pr
esentatlastultrasoundpriortodelivery
1.38
[0.742.56]
Notreported
1.11
[0.631.93]
Definitionof
Denominator
Alldeliveries
1.00
F
=
1.70;
P
=
0.18
46
Alllivebirths
4.22
[0.9618.49]
Allsingletondeliveries
1.28
[0.782.08]
Allsingletonlivebirths
0.82
[0.342.00]
Majorplacenta
praevia(partial
orcomplete)
GBDRegion
Asia
1.00
F
=
2.64;
P
=
0.05
33
30.9%
95.3%
Eu
rope
0.39
[0.210.75]
La
tinAmerica&theCaribbean
0.40
[0.180.90]
NorthAfrica/MiddleEast
0.53
[0.211.31]
NorthAmerica
0.36
[0.170.75]
Su
b-SaharanAfrica
0.67
[0.212.18]
WorldBank
Classification
Highincome
1.00
F
=
0.16;
P
=
0.85
48
Upper-middleincome
0.89
[0.441.81]
Lo
wandLower-middleincome
1.31
[0.335.19]
Languageof
Publication
En
glish
1.00
F
=
0.48;
P
=
0.49
59
Non-English
0.81
[0.431.53]
720 2013 John Wiley & Sons Ltd
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J. A. Cresswell et al. Placenta praevia by world region
8/13/2019 Articulo de Placent Previa
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to any alternative to enhance the validity of our esti-
mates.
The true prevalence of placenta praevia is likely to lie
somewhere between that estimated by the facility-based
and population-based designs. Facility-based studies mayoverestimate prevalence because of referral patterns. Con-
versely, estimates from population-based studies may
underestimate the prevalence of placenta praevia due to
the increased potential for missing cases. Population-
based studies are more likely to lack detailed information
on the grade of the placenta praevia, and clinical diagno-
sis procedures and many population-based studies restrict
the denominator to live births, which excludes cases of
placenta praevia accompanied by stillbirth.
Placenta praevia is a rare condition and may have been
subject to differential under-reporting depending on local
antenatal routines, which are difficult to ascertain at the
aggregate level. For example, one Sub-Saharan studyPrualet al. 2000 reported a substantially lower preva-
lence (0.59 cases per 1000 pregnancies) than other studies
in this review. This study predominantly identified cases
of placenta praevia that were accompanied by a maternal
haemorrhage, and likely missed those with less serious
outcomes, which would be identified in well-resourced
settings where women may have multiple ultrasounds
during pregnancy.
We observed very high levels of heterogeneity in this
review. Most of the studies included in this review had
large sample sizes that produced very precise estimates.
Because within-study variance was very small compared
to between-study variance, high I2 values were observed.Statistically significant differences between study esti-
mates were not necessarily clinically significant.
In conclusion, the prevalence of placenta praevia is
low, but remains a serious obstetric complication with a
high case-fatality rate. There is some evidence to suggest
regional variation in the prevalence of placenta praevia,
although it is not possible to determine from studies such
as this whether this is due to true population differences
or some unknown factor.
Acknowledgements
This project was funded by a grant from the Bill andMelinda Gates Foundation to the US Fund for UNICEF to
support the Child Health Epidemiology Reference Group
(PI: Robert E Black). The authors acknowledge the valu-
able contributions of Alma Adler, Sara Thomas and Karen
Wagner to the project. The authors would like to thank
Fernanda Boueri, Kathryn Church, Xing Lin Feng, Sylvia
Marinova, Ana Montoya, Yusuke Shimakawa and Kate-
rini Storeng for their help translating articles.Table2
(continued)
Studycharacteristic
OR
[95%
confidence
interval]
Testforc
ovariate
withKnapp-Hartung
modification
Proportion
ofbetween-study
varianceexplained
(AdjustedR2)
Residual
variation
duetostudy
heterogeneity
(ResidualI2)
Confirmation
ofPlacentaPraevia
Diagnosis
Confirmedatdelivery
1.00
F
=
1.43;
P
=
0.26
30
Pr
esentatlastultrasoundpriortodelivery
0.96
[0.541.69]
Notreported
0.32
[0.081.31]
Definitionof
Denominator
Alldeliveries
1.00
F
=
0.10;
P
=
0.75
57
Allsingletondeliveries
1.09
[0.621.92]
2013 John Wiley & Sons Ltd 721
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J. A. Cresswell et al. Placenta praevia by world region
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Supporting Information
Additional Supporting Information may be found in the
online version of this article:
Appendix S1. Description of eligible studies.
Corresponding AuthorJenny A. Cresswell, London School of Hygiene & Tropical Medicine, Keppel St, London WC1E 7HT,
UK. E-mail: [email protected]
724 2013 John Wiley & Sons Ltd
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J. A. Cresswell et al. Placenta praevia by world region