By Therese Raphael

Bloomberg View

Whatever part of America President Donald Trump was making great again when he set the goal of reducing immigration by half, it wasn’t the part with working parents. It’s great to have immigrants with advanced degrees who can program in five coding languages. But his proposal to slash legal immigration and admit applicants based on skills instead of family ties leaves out a lot of useful workers — among them, people who take care of young children.

Access to high-quality, affordable and flexible child care is already inadequate in much of the U.S. for all but the well-off, and government spending on child-care and early education is among the lowest of all developed nations. These failings have huge costs: Decades of research have established the link between quality child care and lifelong benefits from academic performance to health outcomes and earning potential.

Not only does high-quality child care benefit children and families, it also brings wider economic benefits, as former Fed Chairman Ben Bernanke once noted:

“Economically speaking, early childhood programs are a good investment with inflation-adjusted annual rates of return on the funds dedicated to these programs, estimated to reach 10 percent or higher. Very few alternative investments can promise that kind of return.”

Trump’s ideas would only make the situation for working parents worse — and poorer families would lose the most. In 2015, 1.8 million people worked in early-childhood care and education in the U.S. compared to 1.1 million in 1990, an increase of 56 percent, according to the Migration Policy Institute. Nationally, 18 percent of those workers are immigrants; in California, it’s one in four.

I have spent most of my adult life in Europe and Britain, where child-care options are more plentiful and often more affordable than in the U.S. In part due to an abundance of European migrants — but also more government spending in the area — the U.K. in particular has enjoyed fairly high standards of child care.

The consequences of inadequate child-care provisioning can already be seen in London. While U.K. parents generally have more options than American parents, child-care costs in London are a third higher than the national average and there is a chronic undersupply, with only 32 places for each 100 children under age 5.

Neither in the U.K. nor the U.S. is anything set in stone. Prime Minister Theresa May could recognize that ensuring adequate child-care provisions, like ensuring that the National Health Service has access to sufficient numbers of nurses, doctors and other staff, will require higher levels of immigration and at different skill levels, and adjust her hard-line policy to reflect that.

In the U.S., it’s unlikely that Congress will pass Trump’s plan. Plenty of lawmakers in the president’s own Republican Party oppose such strict limits on legal immigration. But lawmakers should do more than simply reject the proposal: They should explain to American families why it would leave them worse off.

Therese Raphael writes editorials on European politics and economics for Bloomberg View.