The newborn boy abandoned in a nativity display at a Queens church last week lucked out. His mother bought towels at a 99-cent store to keep him warm, and then left him in the manger to be found. But many abandoned babies aren’t so lucky. Every year hundreds are dumped in the trash, left to die in the cold or killed by panicked new mothers.

All 50 states have “safe-haven” laws to prevent this, but too few women know about them. These laws allow mothers to surrender their newborns at a police station, firehouse or hospital — no questions asked — without risk of disclosure or prosecution.

On Friday, a 20-year-old cashier at a convenience store near Albany gave birth during the night shift. Terrified, she crammed the infant into a bag, threw him in a dumpster, and hurried back to the register. Her baby was found dead hours later. Now she sits in jail, charged with murder. One life snuffed out, another ruined. Had she known, she could have deposited her baby at a police barracks yards away from the store.

Women who discard or do away with their newborns are typically under 25, unmarried, pregnant for the first time, and living with relatives. Unlike women who kill their older children, they’re not usually mentally ill. Nor are they suffering from post-partum depression. Rather, they lack coping skills to seek help, and almost none has seen a doctor while pregnant. They’re in denial until the day they give birth — usually without going to a hospital — and then they panic.

In response, a district attorney in Mobile, Alabama, devised the first safe-haven program in 1998. Since then, every state has enacted one, but these laws lack a key ingredient: advertising and education to reach young women. The laws are saving newborns — but not enough of them.

New Jersey’s safe-haven law reduced newborn abandonment by 60%. Since Illinois set up its program in 2001, 110 newborns have been turned in. But 75 babies weren’t, and half of them died.

Like the baby born on November 11 in Chicago to a 19-year-old living with her parents. She secretly gave birth in her bedroom. Later that night she heard her mother approaching, panicked, and dropped her newborn out the eighth-story window. Now she’s charged with murder.

Tragedies like this are why the Save Abandoned Babies Foundation is launching an awareness campaign with signs on bus shelters and YouTube videos. The message is that women can safely surrender their newborns.

New York muddled that message by publicizing video of the manger baby’s mother and initially threatening to prosecute her. It set back the cause.

Hospitals also need to counsel women. In Compton, California, on Friday joggers found a crying newborn buried under gravel beside a bike path. The baby was apparently born in a hospital — she was wrapped in a hospital blanket — and her mother could have legally left her there instead of ditching her afterward.

Another answer is baby boxes, already widely used in Europe — even Vatican City. Women can deposit newborns in the temperature controlled, ventilated box, knowing they’ll be rescued in minutes. Some women fear a face-to-face encounter with police or even a nurse. Baby boxes outside public buildings solve that problem.

Outrageously, some feminists oppose these boxes. Feminist studies professor Laury Oaks of the University of California argues instead we need to “eliminate the social injustices that coerce some women and girls to relinquish the right to raise their newborns.”

That’s ridiculous. It’s too late when a woman’s already given birth. At that point, justice means protecting the newborn’s right to live.

Even worse, the United Nations argues baby boxes violate a child’s “right” to know who his parents are. That’s a nice “right” — but not as important as breathing.

Meanwhile, the Queens parishioners who welcomed the manger baby say “it’s a miracle” the mother left the infant there, saving his life. It shouldn’t take a miracle.