As a leader or emerging leader, there will be times when you feel the desire to share something fairly private with another person–either a colleague you trust or perhaps a pal in the same field. Maybe you need a sympathetic ear to gripe to about a problem, or you want a second opinion on a move you’re thinking of making, or you feel the urge to brag a little about an accomplishment, like the fact that your boss is considering you for a promotion.

But here’s my advice for those occasions. Resist. Do not breathe a word. Because if you share this secret information, there’s a 60 percent chance the person will break your confidence.

That, by the way, is not based on some big study I saw. It’s simply my best estimate from years of experience, including experience being burned.

People, you see, are by and large incredibly indiscreet. They swear that they will keep your secret “in the vault” or “under the cone,” but guess what? There is no vault and there is no cone.

In some cases they blab because they’re just compulsive gossipers; they’re thinking of who they can spill to even while you’re still speaking.

Other people start out intending to be button-lipped, but a moment arrives when sharing the secret will make them seem wonderfully in the know, and they can’t resist. Even if they don’t out and out spill all the beans, they may nonetheless drop tantalizing hints.

When I was pregnant with my first child, I decided to wait to tell my boss until I was past the three-month mark because I sensed my pregnancy might throw her a curve ball and there seemed no point in shaking things up until I was out of the major miscarriage zone. Just before I was planning to break the news, I flew to San Francisco for a business trip with several people from the advertising sales department. After one of the women on the trip expressed surprise at the number of Caesar salads I was consuming (I utterly cravedthem during the second trimester), I confided that I was expecting. I figured no one would betray that kind of secret. WRONG. She told her boss who then told my boss.

It clearly made the blabber feel special to turn over this piece of gossip, but my boss was pissed that she was one of the last to know. It took weeks to smooth things over.

I learned my lesson the hard way, but it took.

To some degree you can learn to spot secret blabbers. Note the people who tell you something they heard in confidence from someone else, claiming they’re just telling you. But unfortunately you can’t always pinpoint who will betray you. That’s why it’s smart to just keep your lips sealed and be your own counsel.