In 2006, 45 Hezbollah missiles fell in the streets near Haifa’s Rambam Medical Center, in northern Israel. Not one rocket hit the building. Still, after 33 days of treating the wounded, with explosions going off worryingly close, directors of the emergency ward came to a swift conclusion. This hospital needed to be bomb proof. Rambam was going underground.

Seven years later, a three-story car park sits atop the medical center, as doctors stream down from the ground-floor hospital entrance and go to work. There are facilities for 2,000 patients. This is ER: Underground. This is the largest medical underground facility in the world.

Having dug their way out of that problem, Rambam Medical Center now faces another crisis—smaller and less deadly but with wide ramifications for the state of Israel.

The problem isn’t in the emergency ward, it’s upstairs—in Rambam’s fertility clinic, and more specifically the sperm bank. Stocks have run dangerously low. Nationwide research suggests the problem is endemic and that all of Israel’s 15 sperm banks could close if more semen doesn’t start arriving soon.

Part of Israel’s semen crisis is the dwindling number of donors. Media speculation about whether their anonymity will always be guaranteed has scared them off, according to Professor Daphna Birenbaum-Carmeli, a medical anthropologist who works across town from Rambam, at Haitha University’s nursing school. In recent years, the religious establishment, obsessed by the genetics of their Jewish congregation, has called for anonymity to be lifted. They want to prevent mamzerut or illegitimate children.

“Nobody is expecting new laws to open up the sperm bank records retrospectively,” she explains, “but the talk about disclosure means its getting harder and harder to find donors to come forward.

Birenbaum-Carmeli has also seen a change in attitude towards artifical insemination.

“In the Eighties, this was all a very discreet process. Male infertility was extremely stigmatic: it was falsely conflated with impotence. People didn’t even know sperm banks existed—it was an easy but very discreet way for a few students to make some extra money.”

“Now reproductive technology has come to the surface, this is putting people off. Clinics are everywhere and people are more nervous.”

Birenbaum-Carmeli also points to technology that means even a near-sterile man can now be assisted to impregnate his wife.

“Most of the clients at Israel’s sperm banks are now single women, and lesbian couples.”

“And people realize that this sperm banks are now a solution to a womens problem, not a man’s,” she adds.

Male machismo might be denting the numbers of donors—but Rambam is fighting back.

“We took 10 students. Put them in a room. Gave them colouring pencils,” explains a spokesperson. “We told the students there are no rules—you can say what you want, you can draw what you want, as long as you think its funny. Draw us a new advert for our sperm banks.”

The results were strange, compelling, puerile, trashy and slightly brilliant—laser-targeted towards young Israeli males. One shows a military helmet and the exhortation: “Man! Contribute to a mother’s struggle.” Another, showing a bouncy baby, says, “Giving sperm—more pleasant than giving blood.” Then there’s poster of a handsome fellow with the tagline, “Do you think you’re God’s gift to women? Prove it.” Or the mock-up of a swimming spermatozoa: “Do you come quickly? At least make some money from it.”

While they might raise eyebrows amongst Israel’s more conservative members, early signs are positive. Slightly more men are coming forward, though there’s a long way to go.

“It’s a big problem, we’re having it the same as everyone,” explains Dr. Shahar Kol, of Rambam Fertility Clinic. “We have five active donors, two currently under consideration.”

It is the same scenario at several other clinics I spoke to, with several confessions they are down to a single figure number of donors.

But there’s an even bigger problem: quality. The numbers of donors rejected because of a low sperm count in their semen is skyrocketing. (This problem is not just occurring in Israel, but in France as well, according to a recent study in the journal Human Reproduction.)

The latest long-term study in Israel shows that in 1995, about a third of potential semen deposits were rejected. Nowadays, that number would be closer to 90 percent, had the govenrment not dramatically relaxed quality criteria in 2004 to cope with the shortage. Even with the new, looser rules, 40 percent of donors are being rejected. In one of the more selective sperm banks, who run a “premium” list of donors, just one percent are being accepted. Researchers posit the lack of high-quality donors could spell the end of sperm banks in Israel.

Deteriorating quality of semen is a problem across the developed world, not just in Israel. But in Israel quality is worsening faster than anywhere else . The sperm banks are just the tip of the iceberg.

Scientists can’t explain why sperm counts are going down, and the theories number into the dozens, from depleted uranium leaking into the water supply to industrial dairy farming techniques, to the classic smartphone-carried-in-the-pocket. As one academic puts it, “We have a lot of theories, but we can’t prove a single one of them.”

Still, it’s important to note that sperm banks themselves account for just a few hundred births each year. So they are a litmus paper for wider fertility—not a significant driver of Israeli birthrates. And although semen in Israel seems to be deterioating faster than elsewhere in the developed world, overall birth rates are high. The spread of Jewish Orthodoxy is creating more families with large numbers of children.

So what happens if Rambam Fertility Clinic is forced to close the sperm bank? “We serve Northern Israel with 650 donor sperm samples a year,” explains Dr. Kol. If we did close, all those patients would simply be denied the opportunity to become mothers.”