Z Geburtshilfe Neonatol 2004; 208 - 146
DOI: 10.1055/s-2004-829351

New and improved population-based German reference data for preterm infants growth

W Mihatsch 1, F Polandt 1, K Koetting 2, M Voigt 3
  • 1Division of Neonatology and Pediatric Critical Care, Department of Pediatrics
  • 2Department of Biometry and Medical Documentation, Ulm University, Ulm
  • 3Department of Neonatology und Pediatric Critical Care, Department of Pediatrics, Greifswald University (Ulm, Greifswald, Germany)

Background: Preterm infants growth is best described in form of standard deviation scores (SD scores or z-scores). Effects of nutritional interventions are assessed easily with z-scores. The z-score of a measurement such as weight indicates how far and in what direction that measurement deviates from its distribution's mean, expressed in units of its standard deviation. However, there are no pertinent German population based reference curves available enabling clinicians to easily convert preterm infants growth status into z-scores.

Objective: Aim of the present study was to provide an updated German growth reference for preterm infants.

Methods: Normalized growth standards were constructed by the LMS method1 from a cohort of 1.8 million German singleton newborns born from 1995 to 1997. Data were divided into distinct gestational age groups according to completed weeks of gestation. The power (L), mean (M) and coefficient of variation (S) were calculated for each week of gestation for the variables birth weight, length, head circumference, and weight for length.. Finally smoothed L, M and S curves were computed by standard mathematical procedures.

Results: From 20 to 43 weeks of gestation the L, M and S values for the assessed variables will be presented together with corresponding smoothed curves. If A is the measured anthropometry for the preterm infant, then the z-score is calculated as: z=((A/M)L-1)/(LS). For example for the weight of boys at 25 weeks of postmenstrual age M=790g, L=0.229, and S=0.203. An actual body weight of 500g would correspond to a z-score of –2.136. The full set of data does not fit in this abstract and will be presented at the convention.

Conclusion: The presented data help to assess the growth of preterm infants.

References

Literature: (1) Cole TJ. The LMS method for constructing normalized growth standards. Eur J Clin Nutr 1990;44(1):45–60.

The biometrical evaluation was supported by MilupaR Germany.