APA Dictionary of Psychology

the first measured weight of a newborn, taken within an hour of the child’s birth. The birth weight of the majority of babies is between 5.5 and 10 lbs (2,500 and 4,500 g). Birth weight under 5.5 lbs can usually be explained by prematurity or by a slow prenatal growth rate; it is associated with numerous short- and long-term complications (see low birth weight). Birth weight over 10 lbs is usually explained in terms of large size for gestational age. High birth weight babies are often born to women with diabetes mellitus, gestational diabetes, or obesity. These infants are at elevated risk for labor complications, birth injuries, and morbidity; they have an increased risk of hypoglycemia during the neonatal period (regardless of the mother’s diabetic status) and of obesity later in life.