WASHINGTON (Reuters) - A health insurer with 5.2 million members in three Eastern U.S. states said on Saturday it would stop providing coverage for a procedure called laparoscopic power morcellation that is used in gynecological surgery and may inadvertently spread cancer.

Highmark Inc, which has customers in Pennsylvania, Delaware and West Virginia, will stop covering the procedure on Sept. 1, company spokesman Aaron Billger said in an email.

It is the first insurer to halt coverage of power morcellation after the U.S. Food and Drug Administration advised doctors in April against it and is now considering its risks, the Wall Street Journal reported on Saturday. It said the story was first reported by the Pittsburgh Business Times on Friday.

Johnson & Johnson, whose Ethicon unit is the biggest maker of power morcellators, stopped selling them in April and on Wednesday asked doctors worldwide to return any they have.

The morcellators are used to cut up uterine growths so they can be more easily removed using non-invasive procedures. They are also used in hysterectomies.

But the masses may sometimes be malignant, which is often not detected prior to surgery, and the spinning blade of the morcellators could spread deadly cancer and worsen patient outcomes, the FDA had warned.

Pittsburgh-based Highmark said it is among the largest health insurers in the United States and is the fourth-largest Blue Cross and Blue Shield-affiliated company, with 20,000 employees.

(Writing by Eric Walsh; Editing by Peter Cooney)