Growth Level Of Urban Chinese Infants From Birth To2Years, Body Mass Index Z Scores’ Predicting Model And Its Age Trajectory In Relation To Maternal Pre-pregnancy Body Weight Status

Objectives: To understand the current growth status of the urban Chinese infants0-2years of age and to investigate the effect of factors such as maternalpre-pregnancy body weight status, on the Z score of body-mass index and itstrajectory.Methods: With stratified multi-stage sampling, neonates, born between April1,2009and March31,2010in three Chinese cities Shenyang, Wuhan and Guangzhou,were recruited after their parents had given their consent to participate in the study.Data were obtained on physical examination and from the parents’ administeredquestionnaires regarding feeding and sleeping pattern, etc. The subjects were followedup until the age of2years. Database was established on Epidata3.1with all dataanalyses performed using SAS9.1. Linear mixed modeling method was adopted toestablish the predicting model and the age trajectory of BMI_Z scores.Results:(1) General: A total of2,220neonates were recruited with the ratio ofboys to girls being1.08:1; Follow-ups of11,455person times were carried out whichrepresented a follow-up rate of73.71%.(2) Growth: a) Boys had significant greater values than girls in height, weightand BMI; b) The values of WT_Z, HT_Z and BMI_Z were observed moving towards the right side; c) For both boys and girls between0and2years, the rates ofhigh/higher BMI increased gradually with age, reaching a peak at1year of age, andboys had a significantly higher rate of overweight/obesity than girls at2years old (p=0.0467).(3) The predictors of BMI_Z: a) Infants born to mothers being overweight/obesein pre-pregnancy had, on average, a BMI_Z score of0.30higher than those tomothers with normal body weight in pre-pregnancy; whereas infants to mal-nutritionmothers in pre-pregnancy had a BMI_Z score of0.17lower than their peers tomothers in normal weight group; b) The effect of breastfeeding on BMI_Z at3months varied depending on times: at3months, breastfed infants had a BMI_Z scoreof0.07higher than the bottle-fed peers; the scores were similar between the twofeeding groups at6months, while at year2, breastfed infants had a score of0.30lower than their bottle-fed counterparts which was statistically significant; c) Otherfactors such as paternal body weight status, gestational age, delivery mode were alsofound to be affecting the BMI_Z in children.(4) The trajectory of BMI_Z: Significant effects of maternal pre-pregnancy bodyweight status were observed on the crude BMI_Z for both boys and girls agedbetween0to2years; after adjustment of co-variants, the effects were only found tobe significant for boys but not for girls.Conclusion: a) The growth level of urban Chinese infants is within standards,even beyond the standards set by WHO, and continue to show the secular growthtrend; b) The improved growth level in Chinese children is accompanied with theright-side shift of BMI_Z scores indicating the emergence of obesity problems; c)Maternal pre-pregnancy body weight status has a significant impact on the trajectoryof BMI_Z for boys; and d) paternal body weight status, delivery mode, gestationalage and early life feeding pattern are find to be important predictory factors forBMI_Z score in the urban Chinese infancts.