Even the more developed countries as a region are projected to be home to growing numbers of people in this age group from 2021 until the early 2030s, when their numbers will crest under the medium-fertility scenario at about 219 million. The growth trend in the numbers of young people is most pronounced in the least developed countries, where no peak at all is projected for the foreseeable future. In some sub-Saharan African countries, fertility is barely declining, while the number of women of childbearing age is rising significantly—leading to larger cohorts of young children and adolescents. The United Nations constructs several projections varying by assumptions about fertility, migration and mortality rates.