POLITICS and sheer hatred aside, there is no shortage of blind spots in the rationale behind America’s mounting restrictions on immigration. Immigrants are a boon to America in many ways. For one, they do plenty of jobs that native-born Americans shun—including what most parents would agree is the ultimate labour of love: having babies.

For decades America’s birth rate has been stuck below the level at which a given generation replaces itself. This means that without a steady influx of young migrants down the line there will be fewer working-age people supporting a greater number of retirees. But according to analysis published earlier this week by the Pew Research Centre in Washington, DC, things would have been worse if it weren’t for immigrants. They make up 13% of the population but nearly a quarter of births in 2015 were to immigrant women.

They have slowed the decrease in the number of babies born in America. This is because they have higher fertility rates than natives and make up a growing share of women of childbearing age. Between 1990 and 2015 births shrunk by 4%. Without immigrant women, the drop would have been more than twice as large.

That is not a trend confined to just some parts of America. In all but two of America’s 50 states, immigrants boosted the overall number of births over the last 25 years. Births among native-born women declined in more than three-quarters of states. For immigrant women, they declined only in California and, just barely, in Rhode Island.

On the campaign trail last year, Donald Trump, America's president, said “We love babies.” His hostile line on immigration, however, means America may end up having fewer and fewer of them.