A Glen Head college student gave birth in her bedroom and suffocated the newborn girl before leaving her in a trash bag on the back deck, Nassau police said Friday.

Sharon Seudat, 20, who was taken into custody Friday, was scheduled to be arraigned Saturday on a second-degree murder charge, police said.

Officers and firefighters responding to a 911 call for medical assistance on Thursday morning found Seudat suffering from profuse vaginal bleeding at her Walnut Street home, police said.

VideoNews conference on Glen Head baby's deathDataLI crime stats

She was rushed to Glen Cove Hospital, where an emergency room doctor determined she had recently given birth, Det. Capt. John Azzata said at a Friday night news conference.

“Originally, there was denial,” Azzata said of Seudat.

When officers returned to the home, they found the dead newborn and bloody clothing.

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“The baby girl was born alive,” the homicide commander said. “As far as we know, it was a healthy baby until it succumbed to asphyxiation.”

He declined to say how Seudat allegedly suffocated the baby and said he did not know why she did it. “I don’t think I’ll ever know the answer to that,” he said.

Seudat, a Nassau Community College student who worked part time at a car wash, hid her pregnancy from her family and the father of her child, who had not been in the picture for months, police said.

When she went into labor, Seudat’s father was at work but her brother and mother were at home, police said.

Her mother rushed into Seudat’s bedroom on Thursday after hearing screams but was still not sure what was going on, police said.

“The baby was already dead,” Azzata said.

Attempts to reach Seudat’s family were unsuccessful.

Azzata said several agencies help distressed, pregnant women, including AMT Children of Hope Foundation, which started in Nassau after a number of dead, abandoned babies were found. Based out of Nassau police headquarters in Mineola, the group was key in pushing through safe-haven legislation.

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New York’s Abandoned Infant Protection Act allows parents to abandon a newborn up to 30 days after birth without leaving their names and without fear of prosecution if the baby is left in a safe manner, such as at a hospital or a staffed fire station.