US sperm donor giant California Cryobank is warning customers it suffered a data breach that exposed customers’ personal information.

California Cryobank is a full-service sperm bank providing frozen donor sperm and specialized reproductive services, such as egg and embryo storage. The company is the largest sperm bank in the US and services all 50 states and more than 30 countries worldwide.

California Cryobank detected suspicious activity on its network on April 21, 2024, and isolated the computers from the IT network.

“Through our investigation, CCB determined that an unauthorized party gained access to our IT environment and may have accessed and/or acquired files maintained on certain computer systems between April 20, 2024 and April 22, 2024,” reads a data breach notification from California Cryobank.

“Out of an abundance of caution, CCB undertook a comprehensive search and review of the files that may have been accessed and/or acquired as a result of the incident.”

An almost a year-long investigation has determined that the attack exposed varying personal data for customers, including names, bank accounts and routing numbers, Social Security numbers, driver’s license numbers, payment card numbers, and/or health insurance information.

California Cryobanks is offering a free one-year credit monitoring to those whose Social Security or driver’s license numbers were exposed in the breach.

The company has implemented additional safeguards and security measures to protect data and monitor their systems.

When sperm is donated, it is commonly done anonymously, with the donor assigned an ID number. This donor ID is then shared with any donor sperm recipients and can be used by offspring when they turn 18 to try and learn more information about their biological father.

It is unclear if donor information, including donor ID numbers, was stolen in the breach, which would be a significant privacy concern to those who donated sperm in the past anonymously.

BleepingComputer contacted California Cryobank to determine if donor data was exposed but has not received a response to our email at this time.