A pregnant woman who was seriously injured in a Wyandanch accident last week has died, police said Tuesday.

Jeanmarie Ott, 28, of Deer Park, was five months into her pregnancy when she was hit by a sport utility vehicle while crossing Long Island Avenue, police and family said.

“It was going to be her first child,” and the first grandchild for Ott’s parents, said Ott’s only sister, Alicia Ott, 26.

The sisters lived at home with their parents, Maryelizabeth Ott, 57, and Theodore Wesley Ott Sr., 53, along with their brother, Theodore Ott, 29.

Suffolk County police First Squad detectives are investigating the accident, which took place at 6:06 a.m. on Sept. 6 at the intersection of Long Island Avenue and Straight Path.

Police said Ott was walking south on Straight Path and was trying to cross Long Island Avenue when she was struck by a westbound 2015 Nissan Rogue.

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The driver was identified by police as Leo Bellotti, 89, of Deer Park. He was not injured and no charges were filed against him, police said.

Jeanmarie Ott was taken to Good Samaritan Hospital Medical Center with unspecified serious injuries, police said. Her family said she was pronounced dead the day after the accident.

Maryelizabeth Ott said the family is distraught over Jeanmarie’s death and that the loss of her baby compounds their grief.

“We were looking forward to having a grandson in January,” Maryelizabeth Ott said.

She said Jeanmarie, who was not married, had carefully picked the name Phoenix for her son.

“She chose the name because of the symbolism — a fresh new start,” Ott said.

Alicia Ott said her sister had chosen to donate her organs upon her death — something Alicia said was typical of something Jeanmarie would do.

She said Jeanmarie worked sometimes taking care of elderly family members of friends.

“She was a caring person who would do anything for anybody and she ended up helping somebody” in her death, Alicia Ott said.

Maryelizabeth Ott said Jeanmarie signed the donation papers when she was 19 years old.

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Family members said Jeanmarie was born and raised in Deer Park and attended Deer Park High School.

Funeral arrangements had not yet been made, Maryelizabeth Ott said.