Birth weight percentile charts based on daily measurements for very preterm male and female infants at the age of 154–223 days

Abstract

Birth weight percentiles based on weekly measurements are used to assess the nutritional status of preterm infants. However, as preterm infants exhibit a rapid growth rate (up to 20 g/kg/day), their body weight can increase by 15% per week. We calculated birth weight percentiles based on daily measurements, to more precisely classify very preterm infants (gestational age of 154-223 days). Data of 23,864 (10,720 females and 13,144 males) very preterm singleton infants with a gestational age of 154-223 days (22-31 completed weeks) were retrieved from the German perinatal statistics of 1995-2000. Percentile curves based on the empirical birth weight data were subjected to three statistical smoothing procedures: cubic regression, local regression (LOESS smoothing), and the LMS method. Smoothing of the birth weight percentiles using cubic regression produced the smallest residual variance. Birth weight percentiles based on daily averages allow a more precise assessment of the somatic development of preterm infants.