摘要:In a case control study the effects of literacy, socio-economic status and the fertility behavior of mothers were fully investigated in two groups. Out of 13123 babies born in 17 hospitals during almost 8 months in 1988-1989 in Tehran 730 had a low birth weight (less than 2500 gr). As a control group, 1460 births were randomly selected from normal weight births. Some basic findings are as follows: 1)Mothers who become pregnant in either age group of “less than 20” or “35 and over” will eventually have a higher chance of delivering a low birth weight baby, and as a result, such babies will gave a higher probability mortality in the first week and first month of their lives. 2) Age at marriage is positively correlated with the level of education. 3) The number of children born alive is negatively correlated with the level of education of mothers. 4) The socio-economic status of the family has a significant impact upon child spacing, and that will affect the probability of having a low birth weight newborn, and finally, will increase the mortality rate of babies.