The decreasing birth rate will forever change human demographics.

In 1968, professors Paul and Anne Ehrlich released the provocatively titled book Population Bomb. The Ehrlichs argued that if the human race kept procreating at its current rate, it was only a matter of time before humans would overrun the planet.

Fast-forward more than 50 years, and many are still alarmed by the prospect of overpopulation. But rather than a baby boom, our biggest worry come 2030 might be a baby drought. 

The key message is: The decreasing birth rate will forever change human demographics.

Since the 1970s, women in the US have had, on average, fewer than two children each. In other words, fewer than necessary to replace the current generation. 

What’s wrong with that? A dwindling population might be good news for the planet’s overtaxed resources. But our current economic system relies on the next generation to care for the elderly and foot the bill for pensions through their taxes. Now, all over the world, from Brazil to Japan, governments are questioning who, exactly, will support their aging populations in the coming decades.

Why is the birth rate declining? Well, these days women are more active in the workforce. So they’re likely to defer starting a family until they’re established in their chosen field. Fertility declines with age, so women who start their families later in life tend to have fewer children.

We’re also having less sex. A study by the Archives of Sexual Behavior found that in the 2010s Americans had sex, on average, nine times less per year than they did in the 1990s. Why? It’s partly because technology has brought a host of enjoyable distractions into our homes – sex is just one pastime among many we can indulge in on a rainy night. 

Not every country’s birth rate is on the decline. The African continent has a current population of 1.3 billion. That’s projected to rise to 2 billion by 2038 and 3 billion by 2061, with the boom concentrated in the sub-Saharan region. 

The African baby boom will have two key flow-on effects. First, sub-Saharan Africa relies on imported food. As its population grows, the markets for feeding and developing agriculture in the region will grow, too, potentially becoming a trillion-dollar sector, according to the World Bank.

Second, many Western nations will need to rethink their hardline stances on immigration. They may soon be dependent on immigrant workers from the Global South to fund and care for their swelling ranks of retirees.