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Population growth: The impact on health and societies

- Africa Health

We have a “golden moment” and “unique opportunity” to spur economic development, says Professor Mark Collinson.

A United Nations report released in 2017 puts the current world population at 7.6 billion people. By 2030 this number is expected to increase to 8.6 billion and eventually 11.2 billion by 2100. With a handful of countries being primarily responsible for this growth, about 83 million people are being added to the population each year even though it is expected that fertility levels will continue to decline. 

Nigeria, the fastest growing country, is expected to become the third largest country in the world by 2050, exceeding the population of the USA. The UN report also states that nine countries – India, Nigeria, the Democratic Republic of the Congo, Pakistan, Ethiopia, the United Republic of Tanzania, the United States of America, Uganda and Indonesia – will house half the world’s population between 2017 and 2050. 


A growing population with disparities in distribution can add strain to the environment to feed people. A World Health Organization (WHO) report published in 2005 explains that overpopulation “is a breakdown of the ecological balance in which the population may exceed the carrying capacity of the environment.” This means weakened food production, leading to inadequate food consumption and malnutrition. 

A report from Cornell University suggests that malnutrition makes people more susceptible to life-threatening diseases like malaria and respiratory infections. From 1950 to 2007 malnutrition increased by 37% and is linked to six million child deaths a year. In 2011 the WHO cautioned that an increase in travel and harmful strains of human-to-human viruses could cause over 100 million deaths in the future as many will be weakened by malnutrition. 

Ageing population 

The decline in fertility rates combined with increased life expectancy in most parts of the world means not only a slowing of population growth but also to an older population. The UN report predicts that the number of people aged 60 and over will more than triple by 2100, accounting for 3.1 billion people. The WHO Global Health and Aging report attributes the increase in elderly population to a change in causes of death, from infectious to non-communicable diseases. Treatment of these diseases, which include hypertension, high cholesterol, arthritis, diabetes, heart disease, cancer, dementia, and congestive heart failure, add pressure to the health care system. 


Generally, population patterns are diverse. Population growth can account for a struggle to get jobs and can cause social and economic strain causing people to migrate to countries with better opportunities. 

Professor Mark Collinson of the South African Population Research Infrastructure Network (SAPRIN), the Medical Research Council / Wits Rural Public Health and Health Transitions Research Unit (Agincourt), says that in the last 20 years fertility rates in Africa have dropped, the working age population has risen and dependency ratios (the number of dependents supported by the working age population) have declined. This, he believes, is an opportunity to spur economic development. 

“The resources – monetary and otherwise – that would otherwise have been absorbed by raising children and supporting large families can be invested in productive and household savings,” says Collinson, who describes this phenomenon as a potential ‘demographic dividend’. 

Collinson says that this demographic dividend is a potential developmental gain created by a window of time where fertility has fallen for several years but the ageing population has not yet risen significantly.

“This can usher in a golden moment when there are relatively few young and few old, and hence a large working age to non-working age ratio.” 

Citing a study by Ahmed et al in 2016, Collinson says that this demographic dividend could account for 11-15% gross domestic product (GDP) growth by 2030 in many African countries, but that policies are needed to enhance the education and employability of young adults, as well as to create greater access to contraception and financial systems. 

In an essay by Aderanti Adepoju of the World Economic Forum Global Agenda Council on Migration Human Resources Development Centre, Adepoju says that the distinctive features of migration include increasing female migration, diversification of migration destinations, transformation of labour flows into commercial migration, and emigration of skilled health and other professionals. 

But, while migration causes a ‘brain drain’ which can have negative consequences in areas such as health where access to health is impacted negatively by the emigration of skilled healthcare workers, and is compromising millennium development goals, it is not all bad. 

According to Adepoju, in sub-Saharan Africa the brain drain is becoming brain circulation within the region, especially from parts of Africa to Cote d’Ivoire, Gabon, Botswana, and South Africa. 

Adepoju also states that remittances received by the migrated worker have been increasing notably and are a lifeline for poor relations left behind as they are able to pay for basic services such as healthcare, education and to enhance agricultural production.

This media release was compiled by following its recent conference in May where Professor Mark Collinson from the MRC/Wits-Agincourt Unit - Rural Public Health and Health Transitions Research Unit (Agincourt) was one of the conference speakers.