Purpose of reviewIn countries with comparable levels of development and healthcare systems, preterm birth rates vary markedly – a range from 5 to 10% among live births in Europe. This review seeks to identify the most likely sources of heterogeneity in preterm birth rates, which could explain differences between European countries.Recent findingsMultiple risk factors impact on preterm birth. Recent studies reported on measurement issues, population characteristics, reproductive health policies as well as medical practices, including those related to subfertility treatments and indicated deliveries, which affect preterm birth rates and trends in high-income countries. We showed wide variation in population characteristics, including multiple pregnancies, maternal age, BMI, smoking, and percentage of migrants in European countries.SummaryMany potentially modifiable population factors (BMI, smoking, and environmental exposures) as well as health system factors (practices related to indicated preterm deliveries) play a role in determining preterm birth risk. More knowledge about how these factors contribute to low and stable preterm birth rates in some countries is needed for shaping future policy. It is also important to clarify the potential contribution of artifactual differences owing to measurement.
Quantifying the burden of stillbirths before 28 weeks of completed gestational age in high income countries: a population based study of 19 European countries.
Objective
Concerns about differences in registration practices across countries have limited the use of routine data for international very preterm birth (VPT) rate comparisons.
Design
Population-based study
Setting
27 European countries, the United States, Canada and Japan in 2010.
Population
9,376,252 singleton births.
Method
We requested aggregated gestational age data on live births, stillbirths and terminations of pregnancy (TOP) under 32 weeks, and information on registration practices for these births. We compared VPT rates and assessed the impact of births at 22-23 weeks GA, and different criteria for inclusion of stillbirths and TOP on country rates and rankings.
Main outcome measures
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 22-23 weeks (between 1% and 23% of very preterm births) and stillbirths (between 6% and 40% of very preterm births). After excluding births 22 to 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 GA 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.
IMPORTANCE-Clinicians have been urged to delay the use of obstetric interventions (eg, labor induction, cesarean delivery) until 39 weeks or later in the absence of maternal or fetal indications for intervention.OBJECTIVE-To describe recent trends in late preterm and early term birth rates in 6 highincome countries and assess association with use of clinician-initiated obstetric interventions. EXPOSURES-Use of clinician-initiated obstetric intervention (either labor induction or prelabor cesarean delivery) during delivery.
DESIGN-Retrospective
MAIN OUTCOMES AND MEASURES-Annual country-specific late preterm (34-36 weeks)and early term (37-38 weeks) birth rates. 2006-2014 (6.0% late preterm; 26.9% early term). Late preterm birth rates decreased in Norway (3.9% to 3.5%) and the United States (6.8% to 5.7%). Early term birth rates decreased in Norway (17.6% to 16.8%), Sweden (19.4% to 18.5%), and the United States (30.2% to 24.4%). In the United States, early term birth rates decreased from 33.0% in 2006 to 21.1% in 2014 among births with clinicianinitiated obstetric intervention, and from 29.7% in 2006 to 27.1% in 2014 among births without clinician-initiated obstetric intervention. Rates of clinician-initiated obstetric intervention increased among late preterm births in Canada (28.0% to 37.9%), Denmark (22.2% to 25.0%), and Finland (25.1% to 38.5%), and among early term births in Denmark (38.4% to 43.8%) and Finland (29.8% to 40.1%).
RESULTS-TheCONCLUSIONS AND RELEVANCE-Between 2006 and 2014, late preterm and early term birth rates decreased in the United States, and an association was observed between early term birth rates and decreasing clinician-initiated obstetric interventions. Late preterm births also decreased in Norway, and early term births decreased in Norway and Sweden. Clinician-initiated obstetric interventions increased in some countries but no association was found with rates of late preterm or early term birth.Late preterm and early term births are of emerging clinical and public health importance and concern due to the associated risks of adverse neonatal and childhood outcomes. 1,2 Preterm and early term births may occur spontaneously or be initiated by clinicians through the use of obstetric interventions such as labor induction or cesarean delivery. In the case of Increasing US preterm birth rates from the 1990s to the mid-2000s were attributed in part to changes in the use of obstetric interventions. [5][6][7][8] Recently, declines in both spontaneous preterm births and preterm births that involved induction or cesarean delivery were documented in the United States over 2005-2012. 9 Several recent US-based hospital and regional studies have documented reductions in elective obstetric intervention at early term gestations, 10-12 but these trends have not been examined at the national level. The relationships between use of obstetric interventions and national-level late preterm and early term birth rates have not been examined in other high-income countries where obstetric interven...
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