Walgreens and CVS, two of America’s largest drugstore chains that already sell more than two dozen kinds of fertility tests, plan to start selling fertility tests for men who want to know whether or not they’re producing enough sperm to get a woman pregnant.

The two drug stores have already begun selling Contravac’s SpermCheck Fertility online, and Walgreens plans to start selling the male fertility test in all of its 7,800 locations starting April.

Contravac said that the test is similar to a pregnancy test, and is a private alternative to going to a doctor. The test sells for $40 and works by analyzing semen samples applied onto a strip that changes color to indicate whether the man has enough sperm for conception.

“In our society, the woman carries the burden of trying to determine the issues surrounding infertility,” Ray Lopez, ContraVac’s chief executive officer told Bloomberg. “Men don’t say, ‘Let me go to the urologist and give a semen sample.’”

According to Lopez, that reluctance has created a $440 million-a-year market for male fertility tests in the United States.

“There is nothing like it on the shelf,” said Maeve Egner, president of Princeton, New Jersey-based Fusion Marketing, hired by Lopez to help market SpermCheck to Bloomberg. “It’s plugging a gap.”

The Centers for Disease Control and Prevention said that about 6.1 million females, which is about 10 percent of all women in the United States ages 15 to 44-years-old have difficulty getting pregnant or staying pregnant, and many times women feeling like they are to blame visit the gynecologist, and very few husbands want to consider that they’re possibly at fault.

While a third of infertility cases are caused by women’s problems, an equivalent 30 percent of fertility problems are due to the man, and the rest caused by a mixture of male and female or unknown problems, according to the U.S. Department of Health and Human Services.

Infertility in men is often caused by an issue known as varicocele, when the veins on a man’s testicle are too big and over heats the testes which can affect the number or shape of the sperm. Infertility can also be caused by other factors like a man making too few or no sperm or abnormal sperm movements that can be genetic or caused by illness like cystic fibrosis.

Heavy alcohol use, drugs, tobacco use, age, environmental toxins, health problems, medicine or radiation treatment for cancer can all potentially reduce the health of number of sperm in men.

Just about two in ten men are willing to accompany their female partners on trips to gynecologists when they’re experiencing trouble with pregnancies, John Herr, the test’s inventor and director of the University of Virginia’s Center for Research in Contraceptive and Reproductive Health in Charlottesville told Bloomberg.

SpermCheck had received Food and Drug Administration approval in 2010, nearly 30 years after Herr, 63, and his team started the research.

“Men have a greater tendency to believe in their invincibility,” Herr said. “When it comes to reproduction, they are more concerned about the delivery vehicle than they are about what’s delivered.”

What’s more, unlike pregnancy and ovulation tests women generally take once a month, men only need to use SpermCheck once to determine their fertility.