Updated

Walgreens and CVS, two of America's largest drugstore chains, are starting to sell a fertility test that will enable men to determine if they are producing enough sperm to get a woman pregnant.

The two drugstores have already made SpermCheck Fertility available online.

Walgreens will begin selling the $40 test across its 7,800 US stores this April.

The test, owned and distributed by ContraVac Inc., comes in a blue-and-gold box and features a smiling couple holding a newborn.

It will add to the nearly two dozen varieties of female fertility tests available in Walgreens stores and fill a longstanding gap between male and female fertility tests.

"There is nothing like it on the shelf," Maeve Egner of Fusion Marketing, the company hired to help market SpermCheck, told Bloomberg News.

"It's plugging a gap," he added.

"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.'"

That reluctance has created a $440 million-a-year market for male fertility tests in the US, Lopez said.

According to the test's instructions, a reddish line indicates the sperm count is normal—20 million or more per milliliter of semen—while a negative result shows no color and indicates that the sperm count is below normal. Any reading below normal means men "should consult a physician about a complete fertility evaluation."