Korena Roberts, 27, from Oregon, US, used a police baton to beat Heather Snively, who was eight months pregnant, to death.
She then used a sharp instrument to cut the unborn baby out. The baby, a boy, did not survive.
Heather Snively's body was found stuffed into a space in kitchen at Roberts' home in Portland, Oregon, in June last year.
Police were alerted to the murder after paramedics were called to the home and discovered Korena's boyfriend, Yan Shubin, trying to revive a newborn baby surrounded by large amounts of blood on the floor.
Roberts, has two children under the age of 10, claimed the baby was hers. She was rushed to hospital where an examination showed that she had not given birth.
Police say they believe Roberts and her victim met online on Craigslist when they were both looking for baby clothes. Roberts apparently lured Heather Snively into her home after saying she wanted to exchange baby clothes. She then attacked her and tried to 'steal' her unborn baby.
Detectives said they believed Roberts deliberately lured Heather Snively to her home with the intention of killing her and stealing her unborn baby.
Four months before the murder, Korena Roberts had told neighbours she was pregnant.
During the bail hearing, Roberts' lawyer said she had given birth to a stillborn child in 2007 and had become obsessed with babies.