Women across America are ditching popular mobile period tracking apps over fears of privacy leaks stemming from the recent reversal of Roe v. Wade, The Guardian reports.

Period tracking apps have become immensely popular, with surveys finding that 1 in 3 American women utilize the convenient smartphone tracking solution. However, some are choosing to get rid of the convenient smartphone option over fears that shaky privacy practices could put their personal information at risk.

Period tracking apps dominate the women’s mobile health tech market, with the two biggest apps, Flo and Clue, having a reported combined userbase of 55 million. These apps also gain a massive amount of personal information from users, such as cycle length and other characteristics. By plugging this information into complex algorithms, tracking apps can predict when the next cycle will occur.

With the overturning of Roe v. Wade, bans on abortions immediately took effect in many states. As a result, the personal information handled by period tracking apps could be accessed by prosecutors in the event a subpoena is issued.

“If they are trying to prosecute a woman for getting an illegal abortion, they can subpoena any app on their device, including period trackers,” Sara Spector, a criminal defense attorney, told The Guardian.

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Last year, Flo was the subject of a class-action lawsuit from eight users, who alleged that the company had sold private information to Google and Facebook.

Months before, the company had agreed to a settlement with the FTC, which alleged that the company had shared personal data from millions of users with marketing and analytics firms, despite promising users that all private health data would be kept confidential. As part of the agreement, the FTC ordered Flo to notify all third parties that shared personal data must be erased.

Just last week, Flo stated on Twitter that “you deserve the right to protect your data” and announced a new “anonymous mode” for the app.

Clue, a Berlin-based company, follows European GDPR privacy laws. Clue claims that users are explicitly told what data is collected and that user’s location data is never collected. Additionally, the company says it will “not respond to any disclosure request or attempted subpoena of their users’ health data by U.S. authorities.”

For those who are leaving mobile period tracking behind, experts recommend using the old-fashioned pen and paper method instead. By marking the start and end dates of cycles on a calendar, individuals can begin to find a pattern and use that to predict when a new cycle will begin.