Romero became the third person to be arrested in the May 5 death of 26-year-old Jana Collins.
She was a newlywed and pregnant when she was shot while sitting in a vehicle with a few other people in the 1900 block of South Corning Street, according to police.
Collins was shot in the head. She and her unborn child died at a hospital.
Detectives believe the Collins was not the intended target, and the incident appears to be gang related.
Romero has been charged with murder and four other felonies in the killing, along with Cecil Levi Laurent, 23, and Asfaw Abebe, 24, who were arrested shortly after the attack, according to the District Attorney's Office.