Variations in very preterm birth rates in 30 high-income countries: are valid international comparisons possible using routine data?
OBJECTIVE
Concerns about differences in registration practices across countries have limited the use of routine data for international very preterm birth (VPT) rate comparisons.


METHODS
Population-based study.


METHODS
Twenty-seven European countries, the United States, Canada and Japan in 2010.


METHODS
A total of 9 376 252 singleton births.


METHODS
We requested aggregated gestational age data on live births, stillbirths and terminations of pregnancy (TOP) before 32 weeks of gestation, and information on registration practices for these births. We compared VPT rates and assessed the impact of births at 22-23 weeks of gestation, and different criteria for inclusion of stillbirths and TOP on country rates and rankings.


METHODS
Singleton very preterm birth rate, defined as singleton stillbirths and live births before 32 completed weeks of gestation per 1000 total births, excluding TOP if identifiable in the data source.


RESULTS
Rates varied from 5.7 to 15.7 per 1000 total births and 4.0 to 11.9 per 1000 live births. Country registration practices were related to percentage of births at 22-23 weeks of gestation (between 1% and 23% of very preterm births) and stillbirths (between 6% and 40% of very preterm births). After excluding births at 22-23 weeks, rate variations remained high and with a few exceptions, country rankings were unchanged.


CONCLUSIONS
International comparisons of very preterm birth rates using routine data should exclude births at 22-23 weeks of gestation and terminations of pregnancy. The persistent large rate variations after these exclusions warrant continued surveillance of VPT rates at 24 weeks and over in high-income countries.


CONCLUSIONS
International comparisons of VPT rates should exclude births at 22-23 weeks of gestation and terminations of pregnancy.
Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Centre for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in Pregnancy, Paris Descartes University, Paris, France.
M
M
Delnord
Department Child Health, TNO, The Netherlands Organisation for Applied Scientific Research, Leiden, The Netherlands.|Department Public Health, Faculty of Medical Sciences, Anton de Kom University of Suriname, Paramaribo, Suriname.
A D
AD
Hindori-Mohangoo
The Infant Mortality and Morbidity Studies Group (TIMMS), Department of Health Sciences, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK.
L K
LK
Smith
Department of Epidemiology and Biostatistics, National Research Institute of Mother and Child, Warsaw, Poland.
K
K
Szamotulska
Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
J L
JL
Richards
Surveillance and Epidemiology Division, Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, ON, Canada.
P
P
Deb-Rinker
Surveillance and Epidemiology Division, Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, ON, Canada.
J
J
Rouleau
Institute for the Care of Mother and Child, Prague, Czech Republic.
P
P
Velebil
Centre for Disease Prevention and Control of Latvia, Riga, Latvia.
I
I
Zile
Estonian Institute for Population Studies, Tallinn University, Tallinn, Estonia.
L
L
Sakkeus
THL National Institute for Health and Welfare, Helsinki, Finland.|Karolinska Institute, Department of Neurobiology, Care Sciences and Society, Division of Family Medicine, Stockholm, Sweden.
M
M
Gissler
Department of Lifecourse Epidemiology, Department of Social Medicine, National Centre for Child Health and Development, Setagayaku, Tokyo, Japan.
N
N
Morisaki
Department of Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA.
S M
SM
Dolan
Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
M R
MR
Kramer
Departments of Pediatrics and of Epidemiology, Biostatistics and Occupational Health, McGill University Faculty of Medicine, Montreal, QC, Canada.
M S
MS
Kramer
Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Centre for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in Pregnancy, Paris Descartes University, Paris, France.
J
J
Zeitlin
D001723:Birth Rate; D002170:Canada / Q000453:epidemiology; D019049:Developed Countries; D005060:Europe / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology
Euro-Peristat; international comparisons; preterm birth; stillbirths; very preterm