Let's think together : Every week the World Bank team in Tanzania wants to stimulate your thinking by sharing data from recent official surveys in Tanzania and ask you a couple of questions. This post is also published in the Tanzanian newspaper The Citizen every Sunday.

Tanzania has experienced an exceptionally high population growth – from 11 million in 1963 to over 45 million in 2012. Among the factors that have contributed to this increase –one of the fastest in the world– is the falling mortality rate. Life expectancy in Tanzania has increased over the past two decades from 50 to 58 years.

In addition, Tanzanian women have continued to have many children (5.4 per woman in 2010), which is higher than Kenya and Rwanda (4.6) as well as other sub-Saharan countries with the exception of Uganda.

Since 1991, this rate has only declined by 13 percent in Tanzania against 26 and 31 percent in Rwanda and Kenya, respectively. Several other factors have also contributed to the high population growth rate that Tanzania is experiencing:

Infant mortality has halved over the last 25 years.

Early marriage: the median age at first marriage in 2010 was 18.8 years in Tanzania compared to 20.0 in Kenya and 21.4 in Rwanda.

Early motherhood: 44 percent of Tanzanian women are either pregnant or are mothers by the age of 19.

Insufficient education: Reaching secondary education considerably delays the age at first marriage and girls with secondary education wed at about 23 years in Tanzania, Kenya and Rwanda. In 2010, women who had no education had twice as many children as those who had attained secondary education.

The average desired number of children for Tanzanian women remains high at 5.3 per woman.

Timid family planning programs; The use of contraceptives has stalled with only 27 percent of women using modern contraceptives in 2010 compared with 39 percent and 26 percent in Kenya and Rwanda respectively in the same year.

With the current fertility and mortality rates, Tanzania’s population is projected to reach 100 million in 2035 and 200 million by the end of this century. These projections raise a number of questions: