Four-dimensional ultrasound imaging is the most powerful witness to the ­humanity of the unborn child.

The three-dimensional image of a child in the womb reveals for the very first time a child’s unique features to expectant parents and creates a live video effect where parents can watch their baby smile or yawn. It happens in real time, hence the fourth dimension in 4-D.

This type of imaging of a fully formed baby in her third trimester is coming live to Times Square on Saturday as part of the “Alive From New York” pro-life rally.

The event comes at a fraught culture moment in our country. It is a time when Americans can see with their own eyes the humanity of the unborn child and can act to protect that life. And yet elected officials across the nation are pushing laws that allow abortion-on-demand for any reason throughout all nine months of pregnancy.

This January, Gov. Andrew Cuomo asked that New York’s landmarks, including 1 World Trade Center’s 408-foot spire, be lit in pink to celebrate passage of the Reproductive Health Act — perhaps the most liberal, and most heinous, abortion law in the country.

That law, cheered by the abortion lobby, allows abortion until the baby’s due date if the mother’s “health” is at risk. But “health” is so broadly defined in the law that it is hard to know what it doesn’t include. The existing precedent in Doe v. Bolton said health considerations could include emotional, psychological and familial factors, as well as the woman’s age.

The New York law is so permissive that it struck from the penal code consequences for killing an unborn child in the womb. The new law explains why ­Anthony Hobson won’t face charges for killing 35-year-old Jennifer Irigoyen’s unborn baby after he stabbed to death both mother and baby in Queens this year. New York now counts unborn life as unworthy of protection against even willful murder.

A bill proposed in the Virginia legislature similarly shocked the conscience. That law would have significantly relaxed restrictions on late abortion, with the sponsor admitting her bill would allow for abortion right up until birth — even during labor.

Specifically, the bill would have reduced the number of physicians needed to certify that a third-trimester abortion would be necessary to protect the woman’s health from three to one: the abortionist. The law would also have loosened language allowing for a late abortion from “substantial and irremediable” damage to the mother to ­impairment of her “mental or physical health.”

Thankfully, the Virginia bill died. But other similarly extreme bills have popped up all across the nation.

A Vermont bill stated that an ­unborn child “shall not have independent rights” under the law. In New Mexico, a bill would have eliminated conscience rights for medical providers who object to performing abortions or referring their patients to abortionists. And Rhode Island’s bill would have ­repealed an existing law that outlaws partial-birth abortion, a grisly procedure in which the abortionist delivers the live baby partially, feet first, and violently causes her ­demise just before full delivery.

It’s worth noting that there’s a huge dissonance between these radical pro-abortion policies and public opinion. Gallup found only 13% of Americans believe abortion should be legal in the third trimester. A Marist survey, meanwhile, found that three in four Americans believe abortion should be limited to — at most — the first trimester.

There’s a huge dissonance, too, between these callous abortion bills and the obvious humanity of the unborn child that will be on display in Times Square on Saturday. It is our hope that the amazing images of life inside the womb will change the hearts and minds of those supporting these bills.

We invite Cuomo and Mayor Bill de Blasio to come down to the square to see the miracle of life for themselves in all its glory.

Jeanne Mancini is president of March for Life.