 Projections for after 2050 have usually assumed that fertility rates will have declined by then and the population will be stable or will decrease.However, a study in 2014 found that fertility rates in Africa have leveled off at around 4.6 instead of continuing to decline, and that consequently world population may be as high as 12 billion by 2100.Reasons for the continuing high birth rate include better survival rates with respect to HIV, and contraception shortage.