CHICAGO, Nov. 17 (AP)  Scientists for the first time have grown human heart valves using stem cells from the fluid that cushions babies in the womb, offering an approach that may be used to repair defective hearts.

The idea is to create new valves in the laboratory while a pregnancy progresses and have them ready to implant in a baby with heart defects after it is born.

The Swiss experiment follows recent successes at growing bladders and blood vessels and suggests that people may one day be able to grow their own replacement heart parts, in some cases, even before they are born.

It is one of several tissue engineering advances that could lead to homegrown heart valves that are more durable and effective than artificial or cadaver valves.