Customized and non-customized live-born birth-weight curves of single and uncomplicated pregnancies from the Burgundy perinatal network. Part I - methodology.

OBJECTIVES: To establish non-customized and customized birth-weight curves of single and uncomplicated pregnancies according to gestational age. MATERIALS AND METHODS: We used data for 64,173 mother-infants pairs from the Burgundy perinatal network database (France) over the period 2005-2013. A validated procedure was used to link mothers with their newborns, and maternal and fetal pathologies likely to affect birth weight were excluded. Multiple regression analysis with covariate selection was used to build a customized growth curve with maternal and fetal parameters. RESULTS: Using this methodology, three different curves were generated: an unadjusted curve for birth weight, named B0, an curve adjusted for fetal gender, named B1 and a curve adjusted for fetal and maternal parameters (fetal gender, maternal height, weight and parity), named B2. CONCLUSION: We present curves showing an original distribution of birth weights for the French population in order to improve the diagnosis of small for gestational age. These curves are not based on the Gardosi in utero growth model but on actual birth weights, thus limiting bias. Nevertheless, the minimum gestational age was 25weeks as there was an insufficient number of live-borns in small gestational ages.