It is believed the woman was the baby's mother.
Emergency services were last night at the scene of the second fatal crash in Hawkes Bay at the intersection of State Highway 2 and Drumpeel Rd in Otane.
Police said a vehicle hit a power pole and rolled on to its roof, killing one of the two male occupants about 6.50pm.
A 600m stretch of State Highway 50 between Meeanee Rd and Link Rd was closed for just over three hours while serious crash investigators worked at the scene.
Speed and impatience are believed to be factors behind a crash that left one man dead in Papatoetoe on Saturday.
The man died after a car crashed into a traffic-light pole on Great South Rd.
The car mounted the kerb on two wheels and was driven along the pavement for about 30m before it hit the traffic lights.
"It drove past the front of a bus shelter, and fortunately there was nobody standing there at the time," said Counties Manukau Senior Sergeant Ian Brenchley.
"It's a straight bit of road. It would appear the driver was just impatient and decided to undertake the other cars at speed by mounting the pavement and struck the traffic light.
"The traffic light was right up to the firewall of the car so the impact was quite hard," he said.
"The speed limit in that road is 50km/h. Speed was definitely a factor but I'm not in a position to say how fast they were going."
Two people - the driver and a front seat passenger - were trapped in the Subaru station wagon when emergency services arrived.
Both occupants were taken to Middlemore Hospital but the passenger's condition deteriorated rapidly and he died a short time later. additional reporting: NZPA
