A woman with cancer inspired Facebook's most controversial employee perk

Last year, Facebook announced it would pay for its female employees to freeze their eggs.

The decision was controversial; some felt the company was encouraging women to work so hard that they'd missed their natural birth cycle. Others celebrated the decision as one that empowered women to become mothers at whatever age they want.

During a discussion with Bloomberg's Emily Chang, Facebook COO Sheryl Sandberg revealed why Facebook decided to offer an egg-freezing reimbursement policy.

Sandberg says the decision was made after an employee with cancer opened up to her.

"The genesis of this particular benefit is an interesting story and one I really learned from, which is that there's a young woman working at -- on Facebook who had got cancer," Sandberg told Chang. "And I knew her and she came to me and said I'm going to go through the treatment and that means I won't be able to have children unless I can freeze my eggs and I can't afford it. But our medical care doesn't cover it."

Sandberg went to Facebook's head of HR and decided the procedure should be covered by the company.

"And then we looked at each other and we said, well, why would we only cover this for women with cancer? Why wouldn't we cover this more broadly?" Sandberg said. "And that was where that benefit came from, and we think it's great."