The pregnant victim sustained a sore stomach but there was no mention of impact on the unborn child.
Still angry, Patangata punched a window of the car, causing it to smash.
His partner was picked up by a family member while the defendant drove the damaged Mazda away.
Police found him at home and breathalysed him but he was just below the criminal level.
Patangata said his rash act had been an attempt to harm himself.
Yesterday, he appeared in the Dunedin District Court after pleading guilty to dangerous driving, driving while forbidden and intentional damage.
He had spent more than a month behind bars awaiting sentencing because he could not provide a suitable bail address, Judge Michael Turner said.
Since 2013, Patangata had been repeatedly involved in family-harm incidents, he noted.
Defence counsel Brendan Stephenson stressed his client was committed to addressing his alcohol problems and had apologised to his partner.
The woman attended court in support of the defendant and the pair wanted to attend couple's counselling.
Judge Turner imposed two months' imprisonment, meaning Patangata would be released immediately.
He added six months of release conditions - to ensure he got the rehabilitative assistance he needed - and banned him from driving for six months.
Patangata was ordered to pay $8558 reparation at $20 a week.
