A recommendation for the definition of "late preterm" (near-term) and the birth weight-gestational age classification system.

Determination of gestational age is important to assess risks for morbidity and mortality in neonates. Definitions for preterm, term and postterm have been precisely defined although definitions for subgroups of infants within these categories have not been well defined. More precise definitions for the subgroup of infants born "near-term" is especially important because of the rapid increase in percentage of births attributed to this subgroup. It is recommended that "late preterm" replace "near-term" because it better reflects the higher risk for complications of preterm birth experienced by this subgroup of preterm infants. Furthermore, it is proposed that "late preterm" be defined as beginning on the 239th day (34 0/7 weeks' gestation) and ending on the 259th day (36 6/7 weeks' gestation) since the first day of the mother's last normal menstrual period.