BJOG. 2007 Sep;114(9):1097-103.
Variation in rates of postterm birth in Europe: reality or artefact?
Zeitlin J, Blondel B, Alexander S, Br?rt G; PERISTAT Group.
INSERM, UMR S149, Epidemiological Research Unit on Perinatal and Women's
Health, Paris, France. zeitlin@cochin. Inserm.fr
Objectives:
To compare rates of postterm birth in Europe.
Design:
Analysis of
data from vital statistics, birth registers, and national birth samples
collected for the PERISTAT project.
Setting:
Thirteen European countries.
POPULATION: All live births or representative samples of births for the year
2000 or most recent year available.
Methods:
Comparison of national and
regional rates of postterm birth. Other indicators (birthweight, deliveries
with a non-spontaneous onset and mortality) were used to assess the validity
of postterm rates. MAIN OUTCOME MEASURES: The proportion of births at 42
completed weeks of gestation or later.
Results:
Postterm rates varied
greatly, from 0.4% (Austria, Belgium) to over 7% (Denmark, Sweden) of
births. Higher postterm rates were associated with a greater proportion of
babies with birthweight 4500 g or more. Fetal and early neonatal mortality
rates were higher among postterm births than among births at 40 weeks.
Countries with higher proportions of births with a nonspontaneous onset of
labour had lower postterm birth rates. The shapes of the gestational-age
distributions at term varied. In some countries, there was a sharp cutoff in
deliveries at 40 weeks, while elsewhere this occurred at 41 weeks.
Conclusions:
These results suggest that practices for managing pregnancies
continuing beyond term differ in Europe and raise questions about the health
and other impacts in countries with markedly high or low postterm rates.
Some variability in these rates may also be due to methods for determining
gestational age, which has broader implications for international
comparisons of gestational age, including rates of postterm and preterm
births and small-for-gestational-age newborns.
