Bad news for anyone running a cafe with a no kids policy, as coffee—the very thing they love over all else—appears to be conspiring against them in a very Longshanksian way. A new study from the National Institute of Health suggests that men who drink at least two cups of coffee a day are twice as likely to get their partners pregnant.

According to the Telegraph, the study took a look at 500 couples trying to conceive and found that the male participants who consumed two or more cups of coffee each day the week before the couple had sex had double the chance of conceiving. Dr. Sunni Mumford, the lead author of the survey, states:

We were somewhat surprised by the results though the research on male caffeine intake and its effects on fertility is pretty mixed.

These results highlight the importance of lifestyle factors in both male and female partners during sensitive windows of reproduction to influence fecundability, and the need for appropriate preconception guidance for couples seeking pregnancy.

The results fly in the face of previous research on the topic that suggests caffeine in fact decreases male fertility by “possibly damaging the sperm DNA,” leading to a lower sperm count. Professor Sheena Lewis of Queens University in Belfast offers up one possible explanation involving caffeine’s effects on adenosine triphosphate (ATP) and guanosine triphosphate (GTP):

Caffeine prevents these chemicals from breaking down so more energy is available to cells including sperm so they can swim faster or longer.

Professor Lewis goes on to note that, were this explanation to be the case, it would be good news for men with fertility issues “because lots of infertility is caused by sperm that are poor swimmers.”

Now, I’m no doctor, but it stands to reason that caffeine could have both positive and negative effects. It could at the same time decrease the total sperm count while supercharging ones that remain; it only takes one little swimmer juiced up on 12 shots of espresso, you know?

Nonetheless, many of the reproductive experts the Telegraph spoke to for the article remain unconvinced by the findings. The prevailing thought in the face of this new study is if your partner is trying to conceive, when it comes to caffeine, don’t change what you are doing just yet. What they do know is this: don’t smoke and don’t drink to excess. Coffee? Maybe.

Zac Cadwalader is the news editor at Sprudge Media Network and a staff writer based in Dallas. Read more Zac Cadwalader on Sprudge.

Top image via Ubisafe.