NAIROBI, Kenya — The director of the Pumwani Maternity Hospital, located in a hardscrabble neighborhood of downtown Nairobi, freely acknowledges that he detains mothers who can't pay their bills.

Lazarus Omondi says it's the only way he can keep his medical center running. Now, a New York-based group filed a lawsuit this month in hopes of forcing Pumwani to stop the practice.

Two mothers who live in a mud-wall and tin-roof slum near the maternity hospital said Pumwani wouldn't let them leave after delivering their babies.

The bills the mothers couldn't afford were $60 and $160. Guards with sticks would beat mothers who tried to leave without paying, one of the women said.

Omondi says one solution to the problem would be a national health insurance program.