Eystna Blunnie, 20, was beaten to death in June 2012 by Tony McLernon, who was later jailed for life.
He left her for dead in the middle of a road in Harlow, Essex, and their unborn baby did not survive the attack.
The family campaigned for two years for a new inquest and her father said they now felt a "proper investigation" had been carried out.
An inquest had been opened and adjourned shortly after the mother-to-be's death, but the coroner had decided a full hearing should not take place following McLernon's conviction.
The jury at the re-opened Chelmsford inquest was told by Essex area coroner Eleanor McGann that a verdict of unlawful killing was the only one they could reach as McLernon had already been found guilty of murder.
Afterwards, her father Kevin Blunnie said: "We feel a full and proper investigation into the facts around our daughter's and her unborn child's deaths have been carried out.
"Some of the failings that we feel were made have been highlighted.
"Also some of the steps that have been made to improve the way procedures are now carried out to protect victims have been explained to us."
Essex Police, Essex Social Care, the Crown Prosecution Service, NHS trusts and Harlow Council were all represented at the inquest.
Det Chief Insp Martin Passmore, who led the murder inquiry, confirmed his force was aware of McLernon's record of domestic violence with previous partners.
The inquest also heard from Miss Blunnie's mother, who said she had seen her daughter with scratches and bruises, while a domestic abuse officer broke down over their "inadequate" response.
Former chief crown prosecutor for the east of England, Grace Ononiwu, also told the jury a lawyer made the wrong decision when they failed to charge McLernon with assault two months before Miss Blunnie's murder.
A heavily pregnant woman murdered by her former partner was unlawfully killed, an inquest jury has ruled.