The effective identification of high-risk neonates with abnormal fetal growth plays an important role in health risk prediction, Prognosis assessment and early intervention [1].

Small for Gestational Age (SGA) and Large for Gestational Age (LGA) describe neonates born with a birth weight below or above defined cut-offs for gestational age (generally the 10th and the 90th centile respectively). This classification identified two categories of neonates having a higher risk for postnatal multiple diseases, not only linked to growth [2, 3]. Indeed, SGA and LGA intercept many neonates with possible intrauterine growth restriction or overgrowth. However, not all the intrauterine restricted growths and overgrowths result in SGA and LGA neonates, and, in contrariwise, some SGA and LGA neonates are constitutionally small or large. The diagnosis of abnormal fetal growth depends on multiple factors, including fetal parameters and accuracy in identifying SGA and LGA neonates. Regarding the latter aspect, the definition of SGA and LGA requires knowledge of gestational age, precise anthropometric measurements at birth, and appropriate reference data for birth weight. Country- or ethnic-specific normative data are important for identifying those at risk. The International Consensus Guideline on SGA [2] recommends the use of national growth charts, when available, or the careful selection of the most appropriate for the region and ethnic-specific population [4], and similar rules should be followed for the identification of LGA.

In 2010, neonatal charts specific for Italian singletons born between 23 and 42 gestational weeks, known as INeS charts, were published [5, 6]. These charts have been widely used for the assessment of neonates and were derived from a nationwide study with a prospective data collection carried out in Italy between 2005 and 2007. The reference set consists of 22,087 girls and 23,375 boys, from 34 centers with a neonatal intensive care unit and neonatology.

The INeS charts were traced separately for first-born and later-born neonates due to a 3% difference in birthweight (BW). To draw these smooth INeS charts, the extended mechanistic growth function (EMGF) method was applied [5]: these charts are completely defined by a function with 10 constants (EGLF-4+1 function), which express the mean pattern of the relation of BW to Gestational Age (GA) according to a prefixed growth model, as well as the conditional standard deviation and skewness of BW. One of the 10 parameters models the difference between first-born and later-born distributions. In a subsequent paper [7], the EMGF approach used to trace the INeS charts was described in detail, and the parameter values of EGLF4 (which differs from EGLF-4+1 only in the absence of the birth-order parameter) were reported.

In some social or emergency contexts, it is not possible to know at the time of delivery the information related to parity. However, on the basis of the above considerations, it is mandatory for the clinical implications to attribute a definition of “high-risk newborn” as reliable as possible.

The aim of this paper, starting from the EGLF-4 function, is to trace birthweight INeS charts for the whole population, i.e., not separated by birth-order. These resulting neonatal charts will serve as a reference when information on parity is unavailable or unreliable, or for better comparisons with other neonatal charts that are not separated by birth-order.