Birthweigh by gestational age in preterm babies according to a gaussian mixture model

Abstract

Objectives. A statistically sound criterion for identifying implausible birthweights for gestational age. Methods. Data are from Italian 1990-94 vital statistics, and concern 42063 single first and second liveborn preterm babies. Two-component Gaussian mixture models are used to describe the birthweight distributions stratified by gestational age. Implausibly large babies are identified through model-based probabilistic clustering. Results. Gestational age appears underestimated of about six weeks in 12.3% of the cases. Large babies are equally present in males and females, but are more frequent among the second borns than in the first borns, even when parity specific models are fitted. Conclusions. The approach allows for a quantification of the gestational age underestimate error and data correction through model-based clustering. Correct birthweigh distributions and growth curves are also provided