The city has stepped up its oversight of day-care centers since the death in August of an infant at a licensed day care facility.

Changes instituted last month at the Bureau of Day Care have led the city to close 204 of the more than 12,000 day-care centers in the city, according to the Department of Health and Mental Hygiene.

The bureau has increased the number of unannounced inspections and follow-up visits it carries out, industry observers said.

The day the infant, Matthew Perilli, died, inspectors had visited his daycare center in Queens and noted that it did not have enough adult supervisors. The inspectors did not close the center, however, because they were to follow up on an unrelated violation.

Now, regulations are being much more carefully enforced, said the executive director of a day-care referral agency, Child Care Inc., Nancy Kolben. “In a regulatory system, you are dealing with individuals who are going out to inspect a home, and there is always some discretion,” Ms. Kolben said, adding that she thinks the department has begun “trying to minimize the amount of discretionary judgment.”

Day-care providers are also on heightened alert as word spreads that more facilities are being shut, especially for having more children than they are licensed to care for, said a senior attorney at South Brooklyn Legal Services, Sarah Dranoff.

Another indication of the crackdown is that surprise visits by inspectors to Chinese-speaking day-care providers have put pressure on the translation services of the Chinese-American Planning Council in Lower Manhattan. That organization has seen an up tick in the number of calls since mid-October, said a director, Doris Woo.

A majority of the closures, 183, have been in-home family day care centers that care for no more than two children under age 2. Twelve group family day-care centers, of the kind where Matthew Perilli died, have been shut.

The closures have strained an already small number of day care centers that care for infants. When Regina’s, a day-care center on President Street in Brooklyn, suddenly closed November 17 – one reason was that it had no exit from the backyard play area – neighborhood parents were sure it would reopen just as quickly. Two weeks later, the center remains closed, though the gate has been fixed. Parents say they still trust the center but cannot hold out much longer.

“A lot of parents have been stuck,” said one mother, Judy Rayner. “Hopefully this will get resolved soon.”