THE 21st century, in one way at least, will be African. In 1990 sub-Saharan Africa accounted for 16% of the world’s births. Because African birth rates are so much higher than elsewhere, the proportion has risen to 27% and is expected to hit 37% in 2050. About a decade later, more babies will be born in sub-Saharan Africa than in the whole of Asia, including India and China. These projections by the UN, if correct, are astounding (see article). There is good reason for the world to worry about Africa’s baby boom.

The danger is not a Malthusian crisis, in which countries run out of food or farmland at some point in the future. It is true that Africa, although vast, is already a net food importer. But that would be fine if Africans were otherwise productive.

The real problem is that too many babies sap economic development and make it harder to lift Africans out of poverty. In the world as a whole, the dependency ratio—the share of people under the age of 20 or older than 64, who are provided for by working-age people—stands at 74:100. In sub-Saharan Africa it is a staggering 129:100.

In stark contrast with most of the world, notably Asia, the number of extremely poor Africans is rising, in part because the highest birth rates are in the poorest parts of the continent. On September 19th the World Bank reported that the number of people living in extreme poverty rose in sub-Saharan Africa between 2013 and 2015, from 405m to 413m (see article). Many African countries already struggle to build enough schools and medical clinics for their existing children, let alone the masses to come.

The experience of other countries where birth rates have fallen sharply is that the number of babies is determined more by parents’ wishes than by anything else. As people move from villages to cities, children become more costly, so couples want fewer of them. As they become wealthier, they have less fear that their children will die. So, on the face of it, economic and social forces should be left to do their work. Moreover, an odd chorus of leftists (who hate racism and Western meddling) and Christian conservatives (who hate abortion and some kinds of contraception) argue that nothing should be done. The trouble is that the reduction in fertility—the number of births per woman—is happening much more slowly in Africa than elsewhere. Half of Nigerians already live in cities, compared with one-third of Indians. Yet Nigeria’s fertility rate is more than double India’s. Overall, the fertility rate in sub-Saharan Africa is dropping about half as quickly as it did in Asia or Latin America when families were the same size.

Four mouths good, two mouths better

African countries need not, and should not, go down the coercive route to smaller families once taken by India, which carried out mass-sterilisation campaigns, or China, which long enforced a one-child policy. This led to, among other horrors, large-scale sex-selective abortions.

Instead there are good examples from within Africa of how to make things better. These involve “small is beautiful” public-information campaigns combined with a government drive to get varied birth control to poor rural areas. Many African governments already have fine-sounding policies to promote contraceptive use, yet too few act on them. Where such policies are a priority, as in Ethiopia, Malawi and Rwanda, fertility rates fall faster than average (though they are still high). Just as many Africans leapfrogged from no phones to mobile phones, and from no power to solar power, so they can jump to innovations like self-injected contraceptives.

High fertility can also be tackled indirectly, by concentrating on the things that are known to affect it—above all, education for girls. Granted, many African schools are awful, with ill-educated teachers who rarely turn up. One way to change that is to encourage private providers, as Liberia has done. Better schools would bring many other benefits to African children—the living as well as the yet-to-be conceived.