Customized birth weight standards for a population in Nanjing, China

Objective To investigate the customized birth weight standards for a population in Nanjing,China.Methods A total of 6 992 women with full-term delivery and singleton pregnancy without fetal abnormalities and pregnant complications admitted to the Drum Tower Hospital,Nanjing,China,between January 2011 and May 2013,were enrolled.At 20-24 weeks of gestation,maternal age,weight,height,origin,history of smoking and alcoholism,gravity and parity were recorded at the antenatal visit,and follow up information in neonatal birth weight,gender and gestational age at delivery was acquired.The customized birth weight equation in Nanjing was established using stepwise multiple regression model.Results The average maternal age,height and weight of the 6 992 women were (27.9±3.8) years,(161.6±4.6) cm and (60.8 ± 7.9) kg,respectively.The average neonatal gestational age and birth weight were (277.4 ± 6.8) d and (3 418.5±353.3) g (2 290-4 810 g).The optimal equation for customized neonatal birth weight=3 410.9+8.87× (height-161.6) +13.42× (weight-60.8)-0.28× (weight-60.8) 2+14.39× (gestational age-280) + 0.02× (gestational age-280) 3+38.47 (gravity 2) or 69.74 (gravity 3) or 34.15 (gravity ≥ 4) +36.60 (parity 1) or 234.37 (parity 2) +105.0 (male neonates).The 10th percentile of neonatal birth weight ≈ 0.87 × the customized neonatal birth weight,and the 90th percentile of neonatal birth weight ≈ 1.13 × the customized neonatal birth weight.Conclusions In Nanjing,China,the customized birth weight of female neonates delivered at 280 days for an average sized primiparous mother (161.6 cm in height and 60.8 kg in weight) is 3 410.9 g,and 2 967.5 and 3 854.3 g at the 10th and 90th percentile,while that of male neonates is 3 515.9,3 058.8 and 3 973.0 g,respectively. Key words: Birth weight;  Infant, newborn;  Fetal development