Fertility analysis is at central importance in demographic analysis as births are a vital component of population growth. The study of fertility also provides important information about women reproductive behavior and attitudes. The term fertility is related to the population projection. The population projection has become one of the most important problems in the world. Population size and growth in a country influence the situation of economy, policy, culture, education and environment etc. of this country and determine exploring and cost of natural sources. The literacy rate is highest in Jorhat district (77.91 %) and is lowest in Dhuburi district (49.86%). (Census 2001). In the census report of 2011, it is seen that the highest growth of population at the district level is Dhuburi which is 24.44. The analysis is based on district level census data of Assam. The analysis shows that the proportion of Muslim population has been rising rapidly in some districts whereas the Hindu population is declining and losing their share in all the districts of Assam. The differential in growth can mostly be explained by large scale migration of people from the neighboring country Bangladesh.