Birthweight percentiles by gestational age in Georgia

Abstract

Background: Development of country specific birthweight percentile by gestational age chart has been suggested to identify small for gestational age (SGA) or large for gestational age (LGA) babies who are at a risk of perinatal and neonatal mortality and morbidity. Objectives: The objective of this study was to construct sex-specific standard birthweight by gestational age chart for Georgia. Methodology: A cross-sectional study was conducted using the Georgia Birth Registry (GBR) for the period of May 2016 to February 2017. All singleton births with complete gestational weeks from 23 to 44 was included in the study. Gestational age were assessed by last menstrual period or ultrasound examination. For constructing the standard chart for newborn only those pregnant women and the newborn who meet the standard eligibility criteria were selected. Altogether,14,230 livebirths were included after exclusion and removal of outliers for analysis. Data from the GBR were analysed using R 3.2.5 software. Birthweight percentiles by gestational age were computed for each completed gestational age week and sex. Generalised Additive Model for Location Scale and Shape (GAMLSS) was used for smoothening of birthweight percentile curves. Results: The mean birthweight was 3276 g and the mean gestational age at birth was 38.76 weeks. 95% of the babies had a birthweight ranging from 2500 g to 4499 g and most of the babies (94.6%) were born during the gestational age 37 to 41 (term week). Generally, males were heavier than females at all gestational ages except at 24 and 29 weeks of gestation. The 3rd, 10th, 50th, 90th and 97th percentile curves were created according to gestational age and sex. The 10th and 90th percentile values of birthweight were higher for males at most of the gestational ages except for few weeks. Conclusion: This is the first study constructing sex-specific standard birthweight percentile chart and curve by gestational age for Georgia. Comparison of the birthweight percentile chart with other countries showed that the 10th and 90th percentile values of Georgia was higher in preterm weeks compared to Norway and Australia. However, the cut-off values for SGA and LGA in term weeks were higher for Georgia compared to WHO, Brazil, Ukraine and Turkey.