NEW YORK — In a campaign believed to be unprecedented in its size and aggressiveness, New York City is handing out the morning-after pill to girls as young as 14 at more than 50 public high schools, sometimes even before they have had sex.

The effort to combat teen pregnancy in the nation’s largest city contrasts sharply with the views of politicians and school systems in more conservative parts of the country.

Valerie Huber, president of the National Abstinence Education Association in Washington, called it “a terrible case once again of bigotry of low expectations” — presuming that teen girls will have sex anyway, and effectively endorsing that.

Some doctors say more schools should follow New York’s lead.

Emergency contraception is safe and effective “if you use it in a timely fashion. It provides relief or solace to a young woman or man who has made a mistake but doesn’t want to have to live with that mistake for the rest of their lives,” said Cora Breuner, a Seattle physician and member of an American Academy of Pediatrics’ committee on teen health.

Plan B emergency contraception is about 90 percent effective at preventing pregnancy if taken within 72 hours after unprotected sex.

New York’s program was phased in in the 1-million-student school system beginning about four years ago. Nurse practitioners or physicians dispense the pills, and parents can sign an opt-out form preventing their daughters from taking part.

Only about 1 to 2 percent of parents have opted out, according to the city Health Department.

The program is seen a way to reduce a startling number: More than 7,000 New York City girls aged 15 to 17 get pregnant each year. More than two-thirds of those pregnancies end in abortions.

“We are committed to trying new approaches ... to improve a situation that can have lifelong consequences,” the Health Department said in a statement.

In the 2011-12 school year, 576 girls received the pills, said Deborah Kaplan, an assistant health commissioner.

Felicia Regina, Parent Association president at Port Richmond High on Staten Island, has two teens at the school, a junior and a senior, and said she has never heard any parents voice objections.

“I do think it’s a good idea,” she said. “The children nowadays are not going to abstain from sexual intercourse. How many unwed mothers do we need?”

Anne Leary, a conservative blogger in Chicago whose children are in their 20s, said the idea is ill-advised and undermines parents’ authority.