Gwyneth Paltrow has been put on blast by a top gynecologist after a contributor to her lifestyle blog advised women to use jade eggs to boost sex.

Earlier this month (Jan17), the actress' Goop site featured an article written by actress Shiva Rose, titled Better Sex: Jade Eggs for Your Yoni.

Shiva, the ex-wife of actor Dylan McDermott, noted: "Fans say regular use increases chi, orgasms, vaginal muscle tone, hormonal balance and feminine energy in general", plus "incredible clearing, cleansing powers".

Shiva also claimed that 'yoni eggs' are a "strictly guarded secret of Chinese royalty", revealing she likes to leave hers outside to gather energy from a new moon or sage burning nearby.

However, San Francisco-based gynecologist, Jen Gunter, told CNN on Friday (27Jan17) that users are opening themselves up to the possibility of infection, particularly if the egg is left inside the body overnight, as Rose suggests in her Goop piece.

"The stones are really porous," Dr. Gunter points out, "so I'm not sure how it could be cleaned or sterilised between uses."

She also takes issue with Shiva's claims on Paltrow's website that the method improves pelvic muscle tone: "You want to contract and relax, not have your muscles contract continually," she explains. "Contracting constantly is like doing half of a bicep curl and not finishing it - that’s not how you work on a muscle."

Still, in the Goop post the writer insists that sexually-active women of all ages can benefit from the strange practice which is most effective when it is a "regular, daily" occurrence. Goop was also selling the jade eggs for $55-66 (GBP43-52), but supplies are currently sold out.