The Preliminary Development Of A Customized Birthweight Standard For Ethnic Chinese Subjects In Nanjing Area

Objective To analyze the physiologic factors affecting birthweight so as to derive the customized birth weight standards for a Mainland Chinese population in Nanjing.Methods This was a consistent cohort study of 6 992 singleton pregnancies between January in 2011 and May in 2013 from Prenatal Diagnosis Center of Drum Tower Hospital Affiliated to Nanjing University Medical School for ultrasound scan to identify fetal structure abnormalities at gestation 20～24 weeks. Maternal weight at booking, height were measured and recorded, at the same time we recorded their ID card number, origin, smoking habits, as well as gravity and parity. After their delivery, we recorded their fetal birthweight, gender and gestational age at delivery. Stepwise multiple regressions were applied to determine the coefficients.Results Total 6 992 cases were eligible to make up the study population. The average maternal age, height, booking weight and BMI of the study group were (27.9±3.8) years, (161.6±4.6) cm, (60.8±7.9) kg, (23.25±2.74) kg/m2, respectively. The newborn average gestational age and birthweight were (277.4±6.8) days, (3 418.5±353.3) g, respectively. The customized fetal weight=3410.9± 8.87*(height-161.6)+13.42*(booking weight-60.8)-0.28*(booking weight-60.8)2+ 14.39*(gestational age-280)+0.02*(gestational age-280)3+gravity (38.47*gravity 2 +69.74*gravity3+34.15*gravity≥4)+parity (36.60* parity 1+234.37* parity 2)+ 105.0* male fetal. The expected female fetal birthweight at 280 days for an average size primiparous mother (161.6 cm,60.8 kg, and non-smoker) for Chinese origin in an uncomplicated pregnancy was 3410.9 g,10th and 90th were±13.23%, this is Y10th≈ 0.87*Y50th, Y90th ≈1.13*Y50th. Male babies were 105.0 g heavier than females. Babies from women who were gravity 2, gravity 3, and gravity≥4 weighed 38.47 g, 69.74 g,34.15 g more than gravity 1, respectively; babies from women who had one or two previous over 20 weeks’deliveries weighed 36.60 g,234.37 g more than the nulliparous.Conclusion In a mainland Chinese population, physiological factors of maternal height, weight at booking, gravity, parity, and fetal gender, gestational age at delivery are important to fetal birthweight. The expected female fetal birthweight at 280 days for an average size primiparous mother (161.6 cm,60.8 kg, and non-smoker) for Chinese origin in an uncomplicated pregnancy was 3410.9 g,10th and 90th were 2 967.5 g and 3854.3 g; The expected male fetal birthweight at 280 days for an average size primiparous mother (161.6 cm,60.8 kg, and non-smoker) for Chinese origin in an uncomplicated pregnancy was 3515.9 g,10th and 90th were 3058.8 g and 3973.0 g。...