When Viagra first hit the scene in 1998, it was the first drug targeted at curing men’s erectile dysfunction — and its success was explosive, if you’ll pardon the pun. Since then, it has been used as an “off-label” cure for a litany of other health issues, including altitude sickness. However, recently, The Cut published an article revealing one lesser-known use for Viagra: as a last-resort fertility aid for women struggling to get pregnant.

Soon after Viagra entered the pharmaceutical market, fertility expert Geoffrey Sher noticed it had the potential to help women who were having difficulty conceiving. In the late 80s, Sher had researched the correlation between the thickness of a woman’s uterine lining and her chances of successful in vitro fertilization. As a woman gets older, her uterine lining, or endometrium, tends to thin, thus leading to an increased rate of IVF failure in older women.

Viagra works in men by increasing blood flow to the penis. Sher surmised that in women it should work similarly, by increasing blood flow to the uterus. The increased blood flow would thicken the endometrium, thereby creating more favorable conditions for an embryo to attach itself.

Sher initially tested his theory on four patients who had tried IVF in the past, with no success. Within eight to 11 days of receiving daily Viagra suppositories directly to their uterus, three of the four women had conceived. Later, Sher confirmed his initial findings with a much larger study, which tested 105 women and found 45% of the women who were treated with Viagra had a live birth after only one IVF cycle.

According to Sher, “hundreds and hundreds of births” have occurred through this fertility treatment in the two decades since these findings. However, Viagra may not the groundbreaking infertility cure-all you’ve been waiting for: It won’t work for everyone.

“It won’t work in women whose basal uterine lining has been destroyed by infection or endometritis … but when the thin uterine lining is a result of reduced blood flow, it is remarkably effective,” Sher told The Cut.

Incidentally, a 2007 study found that Viagra may be leading to lower fertility in men — although results aren’t conclusive, because other evidence suggests that it may have no significant effects on sperm function or ejaculate quality. Now that’s really something to get the blood pumping.