Influential factors on growth parameters in infants using quantile regression analysis

Infant's growth health is one of the important elements effectively on social health. Accordingly, recognizing effective factors on infant's physical growth as well as identifying essential procedures to preserve and improve their health matters is very important. The aim of this study was to determine influential factors on growth parameters including height, weight and head circumference of infants using quantile regression analysis. This cohort analytic descriptive study was conducted in Islamic research committee of Shahrekord University of Medical Sciences from Ramadan 2006 to 2009. 92 healthy infants including entrance criteria were studied. The impacts of effective factors on growth parameters like height, weight and head circumference in various quantiles were compared using quantile regression model. Growth parameters have a direct relationship with the birth weight of infants. The direct relationship of mother's age was pretty apparent up to 6th month. Birth rank had a reverse effect on growth parameters. Iron consumption at the 20 and 40 quantiles of height and feeding of mother’s milk at the second deciles of head circumference was significant (P<0.05). Due to fit of various regression lines, obtained results indicated that quantile regression is more comprehensive than a linear regression model. Effectiveness of variables of father's education, birth rank, mother's Body Mass Index, the number of family members, iron intake, vitamin and feeding mother milk was not observed by linear regression. Meanwhile, a greater attention is needed to girl's growth especially during the first 6 month after birth.