A preterm birth is a birth occurring before the normal end or term of pregnancy. The normal duration of pregnancy is 40 to 41 weeks. Nonetheless, there are degrees of preterm birth; these are defined according to recommendations of the World Health Organization (WHO).

What we know

The information below reflects the state of knowledge in 2010, prior the launch of the Epipage2 cohort study.


In industrialized countries, between 5% and 12% of births occur before the normal term of pregnancy. In France, there are 60 000 each year, 10 000 (1.2%) before 32 weeks of gestation, and their numbers have been growing regularly. One of every 5 preterm babies is very premature. 

Epipage 1 study

This study, a precursor, so to speak, of Epipage 2, began in 1997. Epipage 1 studied all births before 33 weeks of gestation in 9 regions of France, together with two other samples of children, one born at 33-34 weeks and the other at term.

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