After buying a crib for her baby, Mrs Claudineia dos Santos Melo, 29, was walking home when she was struck by a stray bullet.
The projectile hit the nine-month-pregnant woman in the hip and hit her baby in the lungs, ripped off part of his ear and caused injury to his spinal cord, the Daily Mail reported.
The shot allegedly came from a shootout between drug traffickers and police in Rio De Janeiro, Brazil.
Ms Melo was rushed to hospital where her baby was delivered by emergency caesarean on June 30.
The baby, named Arthur, had to undergo two operations that saved his life. Doctors at the Adao Pereira Nunes State Hospital, where he is in a neonatal intensive care unit, told the Daily Mail that the child could be a paraplegic.
Before the incident, Ms Melo had reportedly been shopping with her husband, Mr Klebsom Cosme da Silva. After shopping, Mr da Silva told the Mail that they split up: He took their purchases home on motorbike, while Ms Melo walked home. It was during her journey that she was caught in the crossfire.
Ms Melo suffered a fractured iliac wing and is warded at a different hospital. Physicians at the Moacyr do Carmo Municipal Hospital told the Daily Mail that while she is stable, there is a potential "risk of infection due to there being an exposed fracture without treatment".
Three men have been arrested for the shooting after eyewitnesses identified them for the police, the Daily Mail reported.