Objective: To analyze the connection between the age of the mother and the birth weight of the new born baby as well as the impact of weight index during pregnancy on the birth weight of the new born baby.Method: Analyze the weight of the 1301 new born babies delivered from January to December 2005 in the First Affiliated Hospital of Chongqing University of Medical Sciences;analyze 576 first time lying-in women who had normal vagina delivery in the First Affiliated Hospital of Chongqing University of Medical Sciences from January 1999 to July 2003

among which there were 184 samples of corpulence during early period of pregnancy with BMI equal to or higher than 24 and 152 samples of corpulence during confinement with BMI equal to or higher than 27.Observe the connection between the birth weight and the age and BMI of pregnant women.Results: Excluding gestational diabetes

non-full-month gestation

double and triple embryo gestation

the average birth weight of 1301 new born babies was 3396g with the average birth weight of 3453g for male babies and 3397g for female babies respectively

among which only those women at the age between 20 and 24 had the new born babies with the weight lower than the average.Compared the corpulent during early period of pregnancy with the compared group

the happening rate of huge baby is evident.Compared the corpulent during confinement with the compared group

the happening rate of huge baby is evident.Compared the weight increase equal to or higher than 15kg during early period of pregnancy with the weight increase lower than 15kg

the happening rate of huge baby is evident.Conclusion: Too young the age of the mother has negative impact on the development of fetus.Too much increase of weight during pregnancy results in increasing happening rate of huge baby.