A billboard on Mission and Valencia streets features a picture of a woman next to a baby and message that says in capital letters, “Abortion Pill Reversal.”

The 12-foot by 25-foot billboard is part of a campaign to promote what health authorities say is an unproven treatment being performed by a network of 270 doctors worldwide.

Its placement – one block from the Planned Parenthood on Valencia Street – is no accident.

“The reason it’s right there is because that’s where abortions are happening,” said Dolores Meehan, the co-chair of the Walk For Life West Coast, and the woman behind the billboard. “You put a lifeguard on the beach, you don’t put them in downtown San Francisco.”

The so-called “reversal,” a procedure championed by George Delgado, an antiabortion family physician from San Diego, involves injecting large doses of progesterone after women begin the process of abortion by taking mifepristone (or RU-486), which blocks progesterone, “the pregnancy hormone.”

Delgado claims that the large doses of progesterone reverse the effects of RU-486.

“There is no evidence that this works,” said Daniel Grossman, vice president of research at Ibis Reproductive Health in Oakland. He will publish an article in the Contraception science journal,  which disproves Delgado’s claims, he said.

“The only published paper is from a series of seven women who got this treatment,” he said, referring to Delgado’s published study in which he injected seven patients with progesterone, with four of the women giving birth.

That study, Grossman said, is “very incomplete, there are a lot of details that are missing. It doesn’t seem like it was done under the ethical review board and there’s a lot of questions about the quality of the study.”

Or as Dr. Cheryl Chastine of Kansas said, the progesterone shots are about as effective as Skittles, because the literature shows that mifepristone on its own is only effective at ending pregnancy half the time. In a second dose, abortion patients get misoprostol, which triggers contractions.

Regardless, the organization behind the annual march that brings tens of thousands of antiabortion activists to the city every year, has paid for the advertising to stay there for two years.

The idea came to the organization last year while members were at a “prayer for life” campaign outside the contested sidewalk on Valencia Street and they saw the billboard.

“That’s when we went, ‘a-ha,’” she said.

So they consulted with Delgado and inked a contract with Clear Channel to erect the billboard from May 28 to June 21 of this year, and then again for two years starting in October (Corona booked the billboard in between those months.) No one has responded to the billboard yet, Meehan adds.

The billboard has the Planned Parenthood staff and advocates worried that it is just another level of deception and harassment. Planned Parenthood did not comment before publication time, but they previously said that it got to the point where a protester would stand outside and take photos of women entering the building.

In 2013, the Board of Supervisors approved an ordinance to create a 25-foot buffer between protesters and the building —it’s based on a similar law in Boston which calls for a 35-foot buffer. A modified version of the ordinance is in place after the Supreme Court struck down the Boston law last year, calling it unconstitutional.

Arizona and Arkansas recently passed laws that would require doctors to tell women using the abortion pill that it can be reversed. Arizona has delayed implementing the law until a federal judge reviews it while the Arkansas law is set to take effect in July.

Back on Mission Street, the Billboard was gone as of Tuesday morning, but Meehan says she is happy that it will return in the fall. Meehan, who is a nurse at a San Francisco hospital, says she has conviction to place the billboard there because science is on their side.

“To say that it’s deceiving,” said Meehan, “it’s, well, deceiving.”