The study objectives were to assess multiple factors associated with the use of contraceptives among married women living in a low income community in Karachi. The study was a cross sectional survey of 608 women between the ages of 15 and 49 years. The mean number of living children per woman was 3.7 (confidence intervals 3.49-3.9). The literacy rate was 53%. The current use of contraceptives was 29%. Among many variables examined and in consistence with studies in other countries, women were 4 to 5 times more likely to use contraceptives if they had 3 or more living children than if they had two or fewer living children (p = .000). These results strongly suggest that the number of surviving children and women's education are key determinants in decision-making about contraceptive use and as such are intervention points to increase contraceptive use. Stronger policies focused on improving child survival, reducing the perceived ideal family size through increased female education will be more likely to reduce fertility.