A morbidly obese Long Island baby sitter accidentally smothered to death a month-old infant when she collapsed and died on the couch where the child was lying, authorities said yesterday.

Teresa Coffey, who was 5-foot-6 and over 200 pounds, was found on top of little Michael Baldwin III on Thursday at around 9:30 p.m. by the boy’s horrified father, and both were pronounced dead at a hospital near the Greenlawn home.

“The woman was described as extremely heavy,” said Detective Lt. Gerard Pelkofsky. “She was extremely large-breasted . . . Because of the amount of flesh, it could have caused the baby to suffocate.”

The boy’s dad, Michael Baldwin — a local TV personality — ditched a broadcast when he couldn’t reach the sitter by phone and raced home.

He found Coffey splayed out on the couch and looked all over for his son.

“I searched every room,” Baldwin tearfully recounted yesterday. “I was saying his name, ‘Michael! Michael!’ ”

When his search failed, Baldwin said he returned to the living room, where Coffey, 39, was “slumped on the couch, face down, her knees on the floor . . . I just had this funny feeling she was on top of him.

“I lifted her and he was underneath. He was lying on his back with his hands folded on his stomach.

“He was blue . . . I just grabbed him and called his name — I knew he was dead.”

Both were pronounced dead at Huntington Hospital.

Baldwin was taping his own show, “Diverse Long Island,” when the freakish events unfolded.

Suffolk Police Detective Lt. Gerard Pelkofsky said investigators believe the deaths were a “tragic accident” — but were conducting autopsies and toxicology tests.

A bottle of prescription pills was found with Coffey, who was known to have health problems, Baldwin said.

Baldwin said he’d gotten a message three hours earlier from Coffey telling him to call her. She never picked up his return calls, and Baldwin, an anchorman for News 12 on Long Island, finally raced home.

“[Coffey] had been asking forever if she could watch my baby, because she couldn’t have children,” Baldwin said.

“She wanted to have kids so bad. I know she had health issues, but I thought she was OK.”

Baldwin said his wife, Colby, is devastated by the death of their only child.

Coffey, who lived in Port Jefferson Station, was also married.

kieran.crowley@nypost.com

