title: Variations in Multiple Birth Rates and Impact on Perinatal Outcomes in Europe.
abstract: OBJECTIVE
  Infants from multiple pregnancies have higher rates of preterm birth, stillbirth and neonatal death and differences in multiple birth rates (MBR) exist between countries. We aimed to describe differences in MBR in Europe and to investigate the impact of these differences on adverse perinatal outcomes at a population level.
  
  
  METHODS
  We used national aggregate birth data on multiple pregnancies, maternal age, gestational age (GA), stillbirth and neonatal death collected in the Euro-Peristat project (29 countries in 2010, N = 5 074 643 births). We also used European Society of Human Reproduction and Embryology (ESHRE) data on assisted conception and single embryo transfer (SET). The impact of MBR on outcomes was studied using meta-analysis techniques with random-effects models to derive pooled risk ratios (pRR) overall and for four groups of country defined by their MBR. We computed population attributable risks (PAR) for these groups.
  
  
  RESULTS
  In 2010, the average MBR was 16.8 per 1000 women giving birth, ranging from 9.1 (Romania) to 26.5 (Cyprus). Compared to singletons, multiples had a nine-fold increased risk (pRR 9.4, 95% Cl 9.1-9.8) of preterm birth (<37 weeks GA), an almost 12-fold increased risk (pRR 11.7, 95% CI 11.0-12.4) of very preterm birth (<32 weeks GA). Pooled RR were 2.4 (95% Cl 1.5-3.6) for fetal mortality at or after 28 weeks GA and 7.0 (95% Cl 6.1-8.0) for neonatal mortality. PAR of neonatal death and very preterm birth were higher in countries with high MBR compared to low MBR (17.1% (95% CI 13.8-20.2) versus 9.8% (95% Cl 9.6-11.0) for neonatal death and 29.6% (96% CI 28.5-30.6) versus 17.5% (95% CI 15.7-18.3) for very preterm births, respectively).
  
  
  CONCLUSIONS
  Wide variations in MBR and their impact on population outcomes imply that efforts by countries to reduce MBR could improve perinatal outcomes, enabling better long-term child health.
authors.affiliation: THL National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Anna
authors.initials: A
authors.lastname: Heino
authors.affiliation: THL National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: TNO, Netherlands Organisation for Applied Scientific Research, Department Child Health, Leiden, The Netherlands.|Anton de Kom University of Suriname, Faculty of Medical Sciences, Department Public Health, Paramaribo, Suriname.
authors.forename: Ashna D
authors.initials: AD
authors.lastname: Hindori-Mohangoo
authors.affiliation: INSERM, Obstetrical, Perinatal and Paediatric Epidemiology Research Team, Centre for Epidemiology and Biostatistics (U1153), Paris-Descartes University, Paris, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Blondel
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen and Medical Birth Registry of Norway, Norwegian Institute of Public Health, 5018, Bergen, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsøyr
authors.affiliation: Ljubljana University Medical Center, Ljubljana, Slovenia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Verdenik
authors.affiliation: Department of Epidemiology, National Research Institute of Mother and Child, Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Mierzejewska
authors.affiliation: Institute for the Care of Mother and Child, Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Velebil
authors.affiliation: Department of Obstetrics and Gynaecology, Landspitali University Hospital, Reykjavik, Iceland.
authors.forename: Helga
authors.initials: H
authors.lastname: Sól Ólafsdóttir
authors.affiliation: Centre for Maternal and Child Health Research, School of Health Sciences, City University London, London, Great Britain.
authors.forename: Alison
authors.initials: A
authors.lastname: Macfarlane
authors.affiliation: INSERM, Obstetrical, Perinatal and Paediatric Epidemiology Research Team, Centre for Epidemiology and Biostatistics (U1153), Paris-Descartes University, Paris, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Zeitlin
mesh_terms: D000328:Adult; D001723:Birth Rate; D005060:Europe / Q000453:epidemiology; D005260:Female; D005313:Fetal Death; D046689:Fetal Mortality; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D008423:Maternal Age; D066087:Perinatal Death; D011247:Pregnancy; D011272:Pregnancy, Multiple; D047928:Premature Birth / Q000453:epidemiology* / Q000401:mortality; D050497:Stillbirth / Q000453:epidemiology*