US tech giants Apple and Facebook will pay for their female employees to freeze their eggs, according to an NBC news report.

It is thought that this offer, which will cover up to $20,000 of egg-freezing costs, is designed to attract the best women in the business, allowing them to postpone having children as they further their career.

Facebook earlier this year introduced cover egg-freezing coverage under its surrogacy benefit, whilst Apple will begin offering in January under its fertility benefit.

They are thought to be the first major employers to provide coverage for the procedure, the costs of which often run at around $10,000 per round plus $500 annually to store for potential in-vitro fertilisation at a later date.

"Having a high-powered career and children is still a very hard thing to do," Brigitte Adams, an egg freezing advocate and founder of the patient forum Eggsurance.com, told NBC.

She said that by offering this benefit, the companies are removing the pregnancy prejudice, and enabling women to make their own decisions about motherhood and career. "It's very forward looking," she said.

A recent survey of the UK and Denmark reported 90% of women consider egg freezing for career reasons as acceptable.

Glenn Cohen, a co-director at Harvard Law School, asked in a blog: "Would potential female associates welcome this option knowing that they can work hard early on and still reproduce, if they so desire, later on?"

"Or would they take this as a signal that the firm thinks that working there as an associate and pregnancy are incompatible?"

This is particularly pertinent to the "boy's club" technology sector, which has come under sustained criticism for the lack of women in the business.

A report released in the summer revealed that Silicon Valley was mostly populated by white males.

This well-documented perception of the industry has been exacerbated by sexual harrassment lawsuits lawsuits, and ill considered remarks such as when Microsoft boss Satya Nadella said women employees shouldn't ask for a raise.

This solution to the sector's demographic imbalance is an extension of its "perks arms race," which has seen companies like Facebook, Apple and Google offer increasingly lucrative benefits to employees.

The egg-freezing procedure, however, is no sure thing. Until 2012, it was listed as an "experimental" procedure, and still very little data is available on the method's success rate.

Meanwhile, as the techniques are improving, demand is skyrocketing – New York and San Francisco fertility clinics say egg-freezing has nearly doubled in the last year.

Christy Jones, founder of Extend Fertility, a company that supports egg-freezing, said: "The attitude toward egg freezing is very different."

The decision is "more one of empowerment than 'this is my last chance.'"