BRUNSWICK — A 21-year-old Brunswick man is being held without bail Friday after police say he pushed his pregnant girlfriend down a flight of stairs Thursday night, sending her to the hospital with injuries to her lower body.

Christopher Mackenzie, 21, was arrested at his home and charged with aggravated assault, a Class B felony, Deputy Police Chief Marc Hagan said Friday.

Brunswick police responded just before 10 p.m. Thursday to the Mackenzie home after neighbors reported hearing two people arguing and the woman crying, Hagan said.

After speaking to the two people, officers arrested Mackenzie.

“We had probable cause to believe that Mr. Mackenzie pushed the 20-year-old victim down a flight of stairs,” he said, declining to give more specific information.

“Just pushing someone down the stairs is enough [to charge someone with aggravated assault], but when you add in the aggravating circumstance that the victim is 22 weeks pregnant,” officers charged Mackenzie with the felony, Hagan said.

The woman was taken to Mid Coast Hospital with “lower body injuries,” Hagan said.

Mackenzie was taken to Cumberland County Jail, where he was held without bail pending arraignment. He is scheduled to appear in Cumberland County Superior Court on June 18.