A pregnant woman was beaten up so badly by her boyfriend that she had to have an emergency delivery, Southampton Town police said Tuesday.

Mohammed Proctor, 38, of Flanders, was held without bail after being arraigned Tuesday on charges of first-degree assault and criminal obstruction of breathing.

On Monday, he punched the stomach and head of Tiffany Norris, 32, who was 71/2 months pregnant, and also tried to strangle her before he took off, authorities said.

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"He claimed she fell down the stairs," said Bob Clifford, spokesman for the district attorney's office, which plans to present evidence this week to a grand jury.

The baby, a girl, was transferred to the intensive care unit at Stony Brook University Hospital, authorities said, while Norris was in serious condition at Peconic Bay Medical Center in Riverhead.

Proctor pleaded not guilty to the charges. He was represented by Legal Aid, which does not comment on cases.

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He was found at home Monday night after a daylong search by patrol officers, detectives and Westhampton Beach Village police, said Southampton police Capt. Lawrence Schurek.

Police had mounted an intensive search for him because he had another young child with him, Schurek said: "We didn't want anything to happen to another child."

The child was not harmed, he said.

Proctor has a record of drug and driving convictions.

He was one of seven men whose drug-related convictions were overturned by a judge at the request of Suffolk District Attorney Thomas Spota after a probe into the Street Crimes Unit of Southampton Town police and an officer who admitted he was addicted to prescription drugs. Proctor had been arrested in April 2010 by Southampton police and charged with criminal possession of a controlled substance, unlawful possession of marijuana, two counts of using drug paraphernalia in the second degree and endangering the welfare of a child. He pleaded guilty on July 13, 2011, and began serving a 2- to 4-year sentence on Oct. 18, but in May 2012, his conviction was vacated. In April 2013, his lawsuit -- in which he claimed police removed a bag of cocaine from his rectum without a warrant -- was dismissed by a federal judge.