A court heard 19-year-old victim Jessy Johnson was just five days away from giving birth when Stuart Samson attacked her after a row.
Leeds Crown Court was shown footage of the incident in which Miss Johnson fell to the ground in pain and was unable to get up.
Prosecutor Peter Moulson, QC, said Johnson then whispered in her ear not to request an ambulance so that social services would not become involved.
Miss Johnson left the Alpha Club, on Southmoor Road, Hemsworth, without calling for emergency services and went to her mother’s home, on April 16 last year.
The court heard Miss Johnson could not feel her baby moving the next day.
She went to hospital after being unable to find the baby’s heartbeat when using a monitor.
A more detailed scan revealed the baby had died.
Her stillborn baby, Mila Frances, was subsequently delivered.
Mr Moulson said Samson’s kick had caused Miss Johnson to suffer injuries which caused the unborn child to suffer from a lack of oxygen.
Samson, 37, went on to attack Miss Johnson for a second time, on February 21 this year, at his flat on Conisborough Way, Hemsworth.
The court heard they had both been drinking and struggled with each other after an argument.
Samson hit Miss Johnson in the face and she suffered a chipped tooth.
Samson pleaded guilty to two offences of assault occasioning actual bodily harm.
Alistair MacDonald, mitigating, said Samson sent text messages after the first attack which demonstrated genuine remorse over the loss of the baby.
He said: “The tragic history of this case revolves around the fact that both parties, I regret to say, had difficulties with alcohol.”
The court heard Samson and Miss Johnson are no longer in a relationship.
Samson was jailed for two years, nine months.
Judge Guy Kearl, QC, said: “In my judgement is was utterly foreseeable that the deliberate blow with your foot to the lower part of her body would cause harm to her unborn baby.
“I bear in mind that I am dealing with you for a kick to the stomach of a pregnant woman.
“You are not charged with any offence relating to the death of the unborn baby.
“However, the fact that the unborn baby, nearly at the end of its term, did die is an aggravating feature.
“You accept that the kick did cause the death of the baby and that is in line with the medical evidence.”