Mark Anthony Powell attacked the victim at her home in Sheffield, pulling out clumps of her hair, biting her cheek and punching her, as she was breastfeeding the infant.
He then choked her, held a knife against her throat and tried to humiliate her by dragging her towards a window after pulling off her top.
When arrested, officers found a banned taser at his home and the attack was committed while he was on bail for driving away from police when they tried to stop him on Whitham Road, Broomhill.
The 24-year-old, of Wath Road, Nether Edge, was jailed for six years and nine months at the city’s crown court in January last year.
He previously admitted assault causing actual bodily harm, possessing a firearm, dangerous driving and driving without a licence or insurance.
Powell challenged his sentence at London’s Criminal Appeal Court, where his lawyers argued the total term was “too long”.
But his appeal was rejected by three senior judges, who said there were no ‘exceptional reasons’ for him to have the taser and the serious attack justified a tough jail term.
But, dismissing his appeal, Mr Justice Sweeney said the sentence was justified, especially in light of the serious and terrifying assault.
He added the assault was ‘a particularly serious one’ and the presence of the baby was an aggravating factor.