Low birth weight frequency and risk factors in Tehran

A case-control study was conducted in Tehran to define the prevalence of low birth weight (L.B.W-weight less than 2500gr) and its associated risk factors during Feb. 1996 to Jun. 1997. Out of 5893 deliveries in eight hospitals, 263(4.4%) resulted in L.B.W. These cases versus 277 controls who were born after every case composed the study sample. There was significant association between mother's age and rate of low birth weight infants (P<O.O I). Birth order was an important risk factor and primigravidity was a greater risk factor for L.B. W delivery than muligravidity (odds ratio= 1.48, 95% CI= 1.04-2. l l). Mother's education level and household socioeconomic status have shown significant association with L.B.W. Variables such as mother's age at. marriage, abortion history and smoking did not show statistical significant association with L.B.W.