Katie Baker, 19, from Tipton, went to Walsall Manor Hospital on Sunday expecting to have her baby but was told to go home – despite telling hospital staff she had no transport or bus fare.
Now the hospital says it will carry out a 'full investigation' into Katie's claims.
Katie, who also has a one-year-old daughter with her partner Clint Jones, 25, told the BBC she waited eight hours to get on a ward on Sunday evening.
"I've already had a child before so I knew that it was going to come soon but they still discharged me," she said.
"I said 'the only way I can get home is walking and that's all the way in Tipton'. They said 'you still have to be discharged'."
Katie said it took over two hours to walk home because she had to stop for a break at a library in Wednesbury.
Paramedics eventually delivered the baby at about 5.30pm and that they were then taken back to Walsall Manor Hospital.
The head of midwifery at Walsall Healthcare NHS Trust, Karen Palmer, said: "I am saddened to hear about this patient's experience in our maternity department.
"The trust is carrying out a full investigation into the concerns that have been raised on behalf of the patient and we will be happy to speak with the patient directly to try to address these."