Relationship Between Body Mass Index, Weight Gain During Pregnancy and Birth Weight of Infants

Birth weight is one of the most important indicators for growth in infants. Therefore identifying the associated risk factors of abnormal birth weight is necessity. This study has been designed to detect body mass index, weight gain during pregnancy and its correlation with birth weight of infants.

Between October 2010 and October 2011 in a cross sectional and descriptive study 1376 pregnant women age range between 18-35 years and gestational age <12 weeks of pregnancy were enrolled. BMI was measured at first prenatal visit and prenatal care was done according to health ministry curriculum. A questionnaire that included demographic, medical history and midwifery data was filled up for each case and preterm delivery cases were recorded. The collected data were analyzed using the SPSS software, logistic regression, student t-test, Fisher’s exact chi-square test.

Univariate analysis showed that LBW was related to mothers in overweight groups, although the differences was not statistically significant (P=1.00). Also the incidence of childbirth with birth weight above 4 kg in overweight and obese mothers was more (P=0.001). On the other hand our statistical analysis results showed an important role for abnormal weight gain during pregnancy, so that weight gain during pregnancy as BMI was affective to predict birth weight of infants (P=0.000, P=0.004).

Results of this study showed an association between abnormal BMI, weight gain during pregnancy and abnormal birth weight. Therefore consultation with a specialist in nutrition for women in reproductive aged could reduce the chance of LBW.