Three-year-old Hamish Pranav Gosai has been brought up by the Plunket book - and has grown exactly in line with the healthy baby charts in the book.
His mum Anjini Kumar, 37, had the advantage of working as a project manager for East Tamaki Healthcare, which allowed her to duck home to keep breastfeeding Hamish after she went back to work part-time when he was nine months old and fulltime three months later.
She gave him no other food for the first six months and kept up breastfeeding to some degree for two and a half years.
"It was my first child and I was going strictly according to what Plunket said," she said at the family home in Goodwood Heights, a five-minute hop from work.
She was also lucky that her parents live with the family. A quarter of all babies in the Growing Up in NZ sample live in extended-family households. Many, like the Fiji-Indian Kumar family, are Pacific people (21 per cent) or Asian (17 per cent).
Hamish's dad Mukesh Kumar, a 42-year-old welder, said Hamish started eating solids at six months but never took formula milk.
"We were trying to top up with the bottle but he refused to take it," he said.
Mrs Kumar started baking chips for him as a toddler, but only "for treats". He also started watching TV from about nine months, but for "limited time".
"We bought a DVD player for his room recently, he just has his few DVDs to watch," she said. "Just 20 minutes or something like that, and we always guide him."
The boy's surnames are those of his paternal grandfather, by Indian custom, and the house ground rules include speaking only Hindi at home, even though he has picked up English since he started preschool.
But neither of his parents can read Hindi so they read to him, and sing lullabies, in English. His kindergarten has taught him to count to five in te reo Maori and he is learning a haka.
Following the Plunket book has paid off. "He has followed the chart exactly," Mrs Kumar said. "He's a very healthy child."