Most Americans think miscarriage is rare. Most Americans are wrong.

Most Americans hugely underestimate the frequency of miscarriage. Facebook founder Mark Zuckerberg’s decision to speak openly about the topic could help change that misperception.

Zuckerberg and his wife, Priscilla Chan, used a pregnancy announcement Friday to share information about her three miscarriages as they’ve tried to conceive in recent years.

Their experience with miscarriage is not a rare one. The best data available suggests that miscarriage occurs in 15 percent of all known pregnancies.

Researchers don’t always understand the cause of miscarriage. They do think it often occurs when an embryo has an abnormal number of chromosomes, essentially too much or too little genetic material. The mother’s health condition – whether she has an infection, for example — could also play a role.

Most Americans underestimate both the frequency of miscarriage as well as the cause. In a survey published earlier this year, researchers at Montefiore Medical Center in New York found that 55 percent of American adults think miscarriage happens in “fewer than 6 percent of all pregnancies.”

Survey respondents were asked to choose possible causes of miscarriage; 76 percent thought a miscarriage could be caused by lifting a heavy object (research disagrees), and 64 percent said previous use of oral contraceptives could play a role (it doesn’t — Pill users actually have lower rates of miscarriage).

In his Facebook post, Zuckerberg talked about the loneliness of experiencing a miscarriage. “Most people don’t discuss miscarriages because you worry your problems will distance you or reflect upon you — as if you’re defective or did something to cause this,” he wrote. “So you struggle on your own.”

Women who have experienced miscarriage tend to feel the same: When the Montefiore researchers looked just at respondents who had miscarried, they found that 40 percent felt ashamed about the experience and 47 percent felt guilty.

There’s the chance that Zuckerberg and Chan’s disclosure could help change this: 28 percent of the women who miscarried said, in the same survey, that “public disclosures of miscarriages by celebrities and public figures helped with feelings of isolation.” Zuckerberg and Chan’s decision to open up about miscarriage could actually help kick off a new conversation.