NEW YORK (AP) — Tales of ballooning mortgage payments are scaring home buyers straight.After taking on risky adjustable-rate loans or multiple mortgages to pay less upfront during the housing boom, borrowers with limited capital for down payments are increasingly opting for safer fixed-rate mortgages backed by private mortgage insurance.

Applications for private mortgage insurance, or PMI, rose 56 percent to 191,525 in March from February, according to the Mortgage Insurance Companies of America, an industry trade group. Volume fell in April, but remained well above rates from last year.

"The consumer is getting more cautious and returning to the tried and true fixed-rate loan with insurance," said Susan Wachter, a real estate professor at the Wharton School of Business.

Private mortgage insurance is typically required of a buyer who wants a fixed-rate mortgage but has a down payment of less than 20 percent. It costs a fixed percentage of the total loan, usually less than one percent, and insures the lender against default.

About $72.9 billion, or 11 percent, of the $680 billion in new mortgages originated in the first quarter were backed by PMI, according to Inside Mortgage Finance, a weekly industry newsletter.

That percentage is rising, said Guy Cecala, the newsletter's publisher — and not just because of consumer caution.

"I don't want to give consumers too much credit," he said. "The growth is also due to the fact that there's been a shift away from 'subprime' mortgages toward conventional ones."

Lenders have curbed loans to people with poor credit after that category had a surge in defaults and delinquencies. To qualify for federal backing from Freddie Mac and Fannie Mae, loans must carry insurance.

But during the housing boom that ended nearly two years ago, lenders were less worried about defaults or federal guarantees, and offered a host of options for borrowers without a large down payment.

Many customers took on loans that had low introductory payments that would reset a few years later. With home prices rising, owners reasoned they could either sell the property before the payment rose, or refinance at a lower or fixed rate.

"People thought the system was working for them, so why pay more initially when prices are rising?" Wharton's Wachter said.

One of the most popular tools was a "piggyback" loan. In what is known as a 80-10-10 loan, borrowers took out a mortgage for 80 percent of the home, paid 10 percent in cash, and then "piggybacked" a second mortgage onto the first for the remaining 10 percent. The second mortgage typically had higher interest at an adjustable rate.