After neighbours took exception to this, a fight broke out, which left the man with head injuries.
When the woman he was with stepped out of the car to help him, the 18-year-old allegedly got behind the wheel and drove the car into a crowd of people, including the pregnant woman.
Another woman suffered a broken foot and a man suffered "a multitude" of minor injuries.
A total of six people were taken to Waikato Hospital by ambulance, Mr Loughrin said.
The woman, who was originally driving, was also charged with drink driving.
Mr Loughrin said support from the community was integral in the charging of the man.
"Given the number of people injured in this incident our response and investigation involved staff from across police which was greatly assisted by the fantastic assistance we received from the local Nawton community. We hope this speedy resolution will confirm to them how much we value that assistance."