Extensive physiologic changes accompany the birth process, sometimes revealing conditions that posed no problem during intrauterine life. For that reason, a person with resuscitation skills must attend each birth. Each neonate is classified as premature, full-term, or postmature to help determine the risk of various complications.
Gestational age, the primary determinant of organ maturity, can be determined in the days immediately after birth using the Ballard score (see Fig. 1: Approach to the Care of Normal Infants and Children: Assessment of gestational age—new Ballard score.). Through plotting of weight vs gestational age (see Fig. 1: Perinatal Problems: Level of intrauterine growth based on birth weight and gestational age of liveborn, single, white infants.), each infant is classified as small, appropriate, or large for gestational age. Head circumference and length are also plotted against gestational age (see Fig. 2: Perinatal Problems: Level of intrauterine growth based on gestational age, body length (A), and head circumference (B) at birth.). These parameters are influenced by genetic factors and intrauterine conditions. They also help to predict subsequent growth and development.
Last full review/revision March 2007 by James W. Kendig, MD