BEIJING, Dec. 20 (UPI) -- China, responding to increased applications by foreign would-be parents, said it will tighten rules on foreign adoptions, U.S. adoption agencies said.

Among the China Center of Adoption Affairs' proposed changes, possibly implemented May 1, would be barring adoptions to people who are single, obese, older than 50 years or don't meet specific benchmarks in financial, physical or psychological health.

China has been the top source of foreign-born children adopted by Americans, The New York Times said Wednesday. Its regulations about who could adopt were less restrictive than other countries, adoption agencies said.

"Their feeling is that while singles can be good parents, it is better for a child to be raised in a two-parent family, it's better for a parent to be educated, it's better for a parent not to be obese because they have a chance of living longer," Jackie Harrah, executive director of Harrah's Adoption International Mission in Spring, Texas, said of the changes.

Agencies said most of people who already began adoption applications would likely be approved if their paperwork were submitted by May 1. International adoption agencies have started denying applicants who don't meet the proposed criteria.