[Levels of low birth-weight in Europe: registration problems and effects of medical interventions].

The rate of low birthweight births, percentage of live births weighing less than 2500 grams is one of the perinatal health indicators recommended by the World Health Organisation. A review of the literature has revealed numerous problems related to this indicator. Some countries, including France and the Netherlands do not collect birthweight data. Elsewhere, there are more than 10% "unknown birthweight". The poorest registration is for birthweights below 1000 grams. Exclusion of babies who were registered as stillborn, when in fact they died shortly after birth can cause underregistration of low birthweights. Conversely, inclusion of true stillbirths will bring on an overestimation of low birthweight rate. Some countries have too few births to deliver accurate rates. Rates of medical interventions, such as infertility treatment and elective induction should be taken into account when analyzing differences between countries. Improvement in quality of registration and caution in the use of this indicator are warranted.