Low birth weight is defined by the World Health Organisation (WHO) as the weight of an infant at birth of less than 2 500 grams (5.5 pounds) irrespective of the gestational age of the infant. This cut‐off figure is based on epidemiological observations
regarding the increased risk of death to the infant and serves for international comparative health statistics. The number of low birth weight births is then expressed as a percentage of total live births. The majority of the data comes from birth registers; however,
in the case of the Netherlands the source is a national health interview survey.