We may be running a bit low on babies.

Last week, the National Center for Health Statistics reported that U.S. fertility had fallen to a record low — for the second straight year. The fertility rate declined to 60.2 births per 1,000 women of childbearing age, down 3 percent from 2016. The number of births in the United States fell 2 percent to 3.85 million, the lowest in 30 years. In fact, the only group for whom birthrates have risen this year is women over 40.

This slump began, somewhat predictably, during the Great Recession. Birthrates tend to drop during periods of economic distress as people put off having babies, but potential parents usually get back to business once the economy rebounds. What’s worrying now is that the recession has more than ended but the baby numbers haven’t picked back up.

It’s hard to know how to gauge a change like this. Alarms about a coming “baby bust” have been sounding for years, while reasonable demographers have cautioned that we shouldn’t jump to conclusions — even though the decline has continued, more or less unabated, for nearly a decade.

Still, even though it may not quite be time to panic, we might want to start thinking about what exactly is going on.

What is holding up the stork? The theories range from the personal to the political. One dourly amusing possibility blames screens: Researchers such as University of Virginia sociologist Brad Wilcox have hypothesized that those of baby-making age are having “too much Netflix, not enough chill.” Young adults may be displacing in-person activities — including forming relationships, getting married and, yes, having sex — with time on computers, phones and tablets. They are posting incessantly on social media, gaming and watching pornography, or Tinder-swiping through all possible matches to find an always-elusive perfect match.

Host, Nicole Ellis explains the step by step process of egg freezing in episode five of The Post's original documentary series, "Should I freeze my eggs?" (The Washington Post)

It’s too early for hard evidence on this theory to have emerged, but it does make a certain amount of sense. One wonders whether the lately media-famous “incels,” for instance, would be as “involuntarily” celibate if they spent less time complaining online and more time out in the real world.

Another possible explanation is a new set of scruples around financial stability and pace of life. Yes, the economy has improved. But the recession and its aftermath have changed the outlook of the most fertile generation in meaningful ways.

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Much has been made of millennials not buying houses and not setting up their 401(k)s, but many of them are postponing other parts of their lives, too, including childbirth and family formation. It’s an understandable choice, considering the distinct lack of parental benefits and profamily policies in most U.S. workplaces. But while postponing children may leave more time to secure a career, there’s less time afterward for securing a family. An uptick of interest in advanced maternal-age fertility treatments and late-in-life motherhood blogs suggests that this may not be the outcome that all would prefer.

One final reason for our latest fertility low may be a newly rekindled political stinginess. The United States’ fertility levels have been below replacement level — the level at which a given generation can exactly replace itself, usually 2,100 births per 1,000 women — since 1971. So why hasn’t America’s population been falling? Because for years, immigrants have been propping up our ranks.

Some would prefer this were not the case. “We can’t restore our civilization with someone else’s babies,” Rep. Steve King (R-Iowa) opined last year, to a deservedly outraged response. In fact, that’s exactly what we have been doing for years, to our country’s great social and economic benefit. Today, however, our political conversation and harsh immigration policies clearly are making relocating to the United State a less attractive proposition. We may want to reconsider our rhetoric before it’s too late — just in case you’re reading, President Trump.

But say we decide not to. The above arguments all assume that falling or plateauing fertility is a bad thing. What if it’s not?

Well . . . it is. The overpopulation doomsday scenarios have long since failed to pan out. Meanwhile, countries that are further along each of these causal trajectories (think Japan, which has the world’s lowest birthrate and has lost 1 million people over the past five years) are facing grim consequences. Not just the economic impact of higher numbers of retirees and fewer young workers but also a distinct sense of social decline — a lack of meaning, an increase in loneliness and a disinterest in the future.

We’re not there yet. But as it turns out — surprise! — having children is generally a good thing. If we’re starting to turn away from it, we should start trying to figure out why.

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