GROWTH ASSESSMENT OF THE NEONATE
Serial measurements of weight, length, and head circumference allow for evaluation of growth patterns.
Weight. Birthweight is reflective of maternal, placental, and fetal environment. During the first week of life, weight loss of 10–20% of birthweight is expected because of changes in body water. Preterm infants lose more weight and regain birthweight slower than term infants. Weight gain generally begins by the second week of life. Average daily weight gain based on normal intrauterine growth is 10–20 g/kg/d (1–3% of body weight/d).
Length. Length is a better indicator of lean body mass and long-term growth and is not influenced by fluid status. Weekly assessment is recommended. Average length gain in preterm infants is 0.8–1.0 cm/wk, whereas term infants average 0.69–0.75 cm/wk.
Head circumference. Intrauterine head growth is 0.5–0.8 cm/wk and is an indicator of brain growth. Premature infants exhibit catch-up growth in head circumference that may exceed normal growth rate, but an increase in head circumference >1.25 cm/wk may be abnormal and associated with hydrocephalus or intraventricular hemorrhage. Average head circumference growth is 0.9 cm/wk in very low birthweight (VLBW) infants. Head circumference is correlated with long-term neurodevelopment.
Weight for length. This can be used to determine symmetry of growth. Current weight expressed as a percentage of ideal weight for length can identify infants at risk for under or over nutrition. Catch-up growth occurs faster if only weight is lagging compared with length and head circumference. Weight gain is slower in large for gestational age infants.
Measurements. Measurements of weight, length, and head circumference are plotted on growth charts to facilitate comparison with established norms. This can help to identify special needs.
Growth charts. Provide longitudinal assessment of an infant's growth. Growth charts for term boys and girls are available from the Centers for Disease Control (CDC) (www.cdc.gov/growthcharts) and from the World Health Organization (WHO). The CDC growth charts are population-based growth reference charts, whereas the WHO charts are growth standards. The WHO charts are based on infants breast-fed from healthy women growing in an ideal socioeconomic environment. Postnatal growth differs between breast-fed and formula-fed infants. The two charts are now merged; the WHO centiles are used before 2 years and the CDC after 2 years (www.who.int/childgrowth/standards/en).
Two types of charts exist for VLBW infants: those based on intrauterine growth and those based on postnatal growth. Intrauterine growth charts provide reference standards. Variations exist in the reference populations for the various growth charts. Intrauterine growth charts are found in Chapter 5. Postnatal growth charts are limited as they do not show the “catch-up growth” or the growth velocity relative to the fetus. Assessment of postnatal growth failure is better reflected on postnatal growth charts. Normal growth customarily falls between the 10th and 90th percentiles when adjusted for gestational age. Recently, population-specific customized growth charts have been developed ...