Samoa’s fertility rate may be the world’s highest by the end of the century, according to a new study published in the Lancet this month.

Based on a future population model where global targets on access to education and contraception are met by 2030, Samoa’s fertility rate is predicted to be 2.51 births per female in 2100. 

It will be one of just three countries with a fertility rate higher than two, the others being Israel with 2.05 and Zimbabwe with 2.03. 

The study, by researchers from the Institute for Health Metrics and Evaluation (I.H.M.E.), modelled the global population’s future based on fertility, mortality and migration. 

They found that the world’s population will likely peak at 9.73 billion in 2064, and that by 2100 the global total fertility rate (TFR) will be just 1.66 births per female. 

It’s a rate that measures slightly lower than the replacement rate of 2.1 (the rate of children to eventually replace adults in society to keep population levels stable), and has the researchers predicting major economic, social and political change as a result.

Professor of Health Metrics and paper author Stein Emil Vollset from the I.H.M.E. said the study offers policy makers a roadmap to preparing for a radically different future to the present.

“Policy makers, based on this, should prepare for a situation where majority of countries will see their populations decline, with fewer children, fewer adults in the workforce to support a growing number of older people,” he explained, saying this will pose a challenge to many countries. 

There is an exception to this, in Africa, which is expected to balloon not only within the century but also after, while majority of countries’ populations fall.

“Liberal immigration policies could distribute the global workforce more evenly. It’s a good idea for the world and for many countries to invest in better education, especially in countries with growing populations that will continue to grow. 

“We could imagine and hope for policies that will make it more attractive for families and women to have and raise children and that type of policy, if successful, would also count to the inversion of the population pyramid.”

Professor Vollset said the important thing about the research and its forecasts is that while they are based on complex and proven data sets and modelling, they do not set the future in stone.

“The overarching message is that our forecast predicts that the global population will grow over the next 40 to 50 years by two billion people but then will decline in the last third of this century by a million, down to 8.8 billion in 2100,” he explained.

“Our predictions are not the future cast in stone. They have wide uncertainty, difference between scenarios, there is ample room to influence the future with the political choices today and in the years ahead. 

“The situation might change rapidly as we have seen with the pandemic.”

Professor Vollset and his colleagues calculate that Samoa’s population will rise to 1.06 million by 2100, or fall to 170,000 should the Sustainable Development Goals on education and contraceptive are met. Samoa’s current population is estimated to be around 200,000, and its fertility rate is 4·69.   

If the S.D.G.s are not met, Samoa will still have the highest fertility rates at 4.47, alongside 12 other countries with a rate higher than two, based on their models.

They predict citizen’s life expectancy to be 79.1 years by 2100, up from 2017 when it was just 70.9. Males are expected to live until 77.9 while females are predicted to live until 80.6. 

Samoa was also found to have among the highest predicted emigration rates, alongside El Salvador and Jamaica, with around 9,200 people leaving Samoa in 2100 and 3,550 in 2050.

The findings were shared in an article titled ‘Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100: a forecasting analysis for the Global Burden of Disease Study.’

They predict that across Oceania, the total fertility rate will fall from current rates of 4.02 to 1.99, or 1.41 should the S.D.G.s be achieved. 

Meanwhile 23 countries including Japan and Spain could lose half their population figures by 2100 if their fertility rates do not change, while China (1.4 billion people today) could lose 48 per cent.

The research was funded by the Bill and Melinda Gates Foundation. Professor Vollset said research on the Global Burden Of Disease (G.B.D.) under which the research was undertaken, is becoming a “vital resource” for public health.

“It includes attributable disease burden due to about 70 risk factors including smoking, alcohol use, air pollution, access to clean water and sanitation  and many, many more,” Professor Vollset said.

“With the COVID-19 crisis the GBD infrastructure that has been built up over the past decade has proven critical for I.H.M.E. to rapidly be able to provide COVID-19 forecasts.”