risk factors in pregnancy and their relation to birth weight

in 17 hospitals, 13123 new births were born during 1989 in tehran. some well-trained personnel observed the events, filling the required questionnaires, interviewing, and collecting necessary information. among them 730 newborns was low birth weight (less than 2500 grams) which was considered as cases. immediately after each case was born, two normal newborn were randomly selected as controls. so at the end of data collection, a total of 1460 births were considered controls. in a case-control study the effect of some risk factors during pregnancy of mothers on birth weight and death rate of newborn during first 4 weeks of their life were fully investigated. some of the findings are as follows: the past history of miscarriages will decrease the birth weight of the newborn and thereby will increase the death rate in the first 28 days of their life. in this respect the difference between case and control was highly significant. other variables like past history of premature birth, chronic diseases, hemorrhage and severe vomiting showed the same results.