Study On Predicting Fetal Birth Weight And Individualized Fetal Birth Weight In Mid - Pregnancy Period

Objective:To evaluate the factors of predicting birth weight and develop a mathematical equation to predict birth weight on the pregnant women characteristics and fetal parameters at20-24weeks of gestation.Methods:235healthy singleton pregnancy women were recruited at Prenatal Diagnosis Center of Jiangsu province from March to May in2011. All pregnant women were in20to24weeks gestational age. They all had regular menstrual cycle of28days before pregnancy. Maternal weight (pre-pregnancy, mid-pregnancy, and at delivery) and body mass index (BMI), maternal age, height, newborn birth weight, the interval from ultrasound examination to term delivery were recorded. At the same time, the fetal biometrics including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and humerus length (HL) were measured. Stepwise multiple regression analysis was used to develop the equation for term birth weight estimation by173women’s data, the left62cases were used to verify the equation.Results:Maternal weight (pre-pregnancy, mid-pregnancy and at delivery) and body mass index (BMI), fetal AC, FL, HL, gestation at birth and the interval from ultrasound scan to term delivery were factors affecting birth weight significantly(P≤0.10). Using the stepwise regression analysis, an optimal formula was derived:estimated birth weight=-501.14+12.52×(time interval from mid-pregnancy to term+34.19x (mid-pregnancy BMI)+8.61×(abdominal circumference) Validation the regression equation, in62cases, there were56cases had absolute error less than±250g (90.32%,56/62). The cases which had an average error below10%between predictive and actual birth weight accounted for91.93%(57/62).Conclusion:Mid-pregnancy BMI, meanwhile fetal abdominal circumference and time interval from mid-pregnancy to term delivery were significant factors for birth weight estimation than other factors in this study. Objective:To develop customized birth weight standards for Nanjing population. Methods:9,484pregnant women were included at their first prenatal examination between18to24weeks of gestation during June2009to December2011.6,754normal singleton pregnancies without recognized risk factors for accelerating or retarding fetal growth were evaluated for maternal characteristics (age, height, booking weight, smoking habits, gravidity and parity) and fetal features (sex, gestational age, birth weight). Stepwise multiple regression analysis was used to determine applicable coefficients.Results:The expected fetal280-day weight of defined standard mother (160cm,59kg, non-smoker, primigravida, Nanjing residents) was3439.1g. Birth weight was correlated with maternal height, maternal booking weight, gestation at delivery with efficient at1.9,10.3,11.4respectively. It also positively correlated with gravidity number (2,+22.5g;3,+38.5g;4,+26.3g). Male newborns were78.5g heavier than female at the same gestational age.Conclusion:Gestational age, gravidity, maternal height, booking weight, and fetal sex are important factors associated with birth weight in Nanjing population.