- Each community-cluster (Mahalla) has an average population of 70,000 and an expected crude birth rate of 4.3 per 1000 total population over 6 months [based on CBR for urban Bangladesh of 25.8/1000 population over 36 months from 2004 BDHS thus giving an average expected number of births of 150 over a 3 month period per Mahalla cluster.