Neonatal anthropometric charts for italian twins

Introduction: This paper aims to present reference data for weight, length and head circumference for Italian twin neonates. Data were obtained as a subproject of the National Prospective Multicentre Study promoted by the Italian Neonatal Society, the Italian Society of Medical Statistics and Clinical Epidemiology, and the Italian Society of Pediatric Endocrinology and Diabetology. Subjects and Methods: Data on 2,814 twins born between 2005 and 2007 were provided by 34 Italian centres. Stillbirths, fetal hydrops, major congenital anomalies were excluded from data collection. Neonates with unreliable gestational age or born to non-Italian parents were also excluded, so that charts were based on data from 1,282 girls and 1,239 boys born between 23 and 39 weeks of gestation. The rationale for inclusion and exclusion criteria specified in the study protocol is discussed elsewhere1. An ad-hoc function was used to smooth raw centiles of the distribution of anthropometric traits. Results: With increasing gestational age twins are progressively smaller than singletons: at 37 weeks body weight is lower by about 275 g (9%), crown-heel length by 1.1 cm (2%), and head circumference by 0.3 cm (1%). The effects exerted on size at birth by gender and parity are proportional to those observed in singletons. Conclusion: Given the differences between singletons and twins, the use of reference charts specific for twins is recommended.