Babson’s growth chart (entitled GROWTH RECORD FOR INFANTS and located on the reverse side of the Ballard exam page (NEWBORN MATURITY RATING)) is included in every infant’s chart. Every infant’s growth parameters (weight, length, and head circumference) should be plotted against gestational age on admission. Classifying an infant as AGA (appropriate for gestational age), SGA (small for gestational age), or LGA (large for gestational age) can help the physician anticipate problems the newborn may encounter.

Every Tuesday at midnight, infants in the NICU have their length and head circumference measured in addition to their q24 hour weighing. These weekly growth measurements should be plotted on Babson’s growth chart to visually assess whether the infant’s growth is appropriate.

Extremely-low-birth-weight infants should have their growth monitored even more closely, and a growth chart designed by Ehrenkranz is included in these infant’s charts. Infants < 1000g birthweight should have their weights plotted qod and their head circumferences plotted q week on this chart also. Meticulous attention to body weight will assist with fluid management in this extremely sensitive population.

Also on Tuesdays, housestaff should calculate the each infant’s growth rate over the past week in "grams gained per kg per day."

Calculation:

1. Calculate the baby’s average weight for the week by adding the baby’s current weight to last Tuesday’s weight and dividing by 2.
2. Subtract last Tuesday’s weight from the present day’s weight to calculate total weight gain for the week.
3. Divide the total weight gain for the week by the baby’s average weight for the week expressed in kg. Then divide the result by 7 days in the week.

The classic goal is to achieve a rate of growth that matches the fetal growth rate of 15 g/kg/day.

However, extremely preterm infants usually experience some degree of postnatal growth failure given the difficulties encountered in providing them with adequate calories particularly early in postnatal life. Almost all of our ELBW population will be discharged home near-term post-conceptual age but with a discharge weight that would be considered SGA if the baby had been growing in utero. Therefore, weight gain rates of 20 - 25 g/kg/day may be desirable if attributable to "catch-up growth" signifying adequate caloric intake. However, such growth rates may also be due to fluid retention, and the baby should be examined for edema and the growth charts examined for an inappropriate pattern.

Growth of < 10 - 15 g/kg/day is inadequate and usually reflects inadequate nutrition. Volume depletion may also account for poor growth rates. The infant and the growth chart should be examined.

Obviously, growth rate calculations are really only useful once an infant is growing and gaining weight. All infants can be expected to lose weight after delivery with their physiologic diuresis and natriuresis. Term infants lose up to 10% of their body weight in the first week of life, while preterm infants may lose up to 15%. In the first week of life reporting "percent below birth weight" on rounds may be more useful than the aforementioned calculation.

Given adequate caloric intake, infants should regain their birthweight by 2 weeks of age. This is also an important milestone to note and report on rounds.

Resolved at Clinical Division Meeting 2/21/99.

References:

Babson SG, Benda GI. Growth graphs for the clinical assessment of infants of varying gestational age. J Pediatr 1976; 89: 814-20.

Ehrenkranz RA, et al. Longitudinal growth of hospitalized very low birth weight infants. Pediatrics 1999; 104: 280-289.