Historically, the definition of prematurity was 2500 grams (about 5 1/2 pounds) or less at birth. The current World Health Organization definition of prematurity is a baby born before 37 weeks of gestation, counting from the first day of the Last Menstrual Period (LMP).
PREMATURITY
Meaning of PREMATURITY in English
English dictionary of medicine. Английский словарь медицины. 2012