Erin Hills, Wisconsin (AFP) - World No. 1 Dustin Johnson says fatherhood has made him a better player as he prepares to defend his US Open title just days after the birth of his second son.

The 32-year-old arrived at Erin Hills on Tuesday after a hectic 24 hours that saw him and wife Paulina Gretzky celebrate the arrival of baby River on Monday.

Johnson, who has been installed as the favourite for this week's title in Wisconsin, described his unusual Major championship build up as an "awesome couple of days".

"Everybody's healthy. Mom is healthy. The baby is healthy. So that's good," he said.

The big-hitting American star has begun to deliver on his talent in recent seasons after a series of Major near-misses.

A second-place finish at the 2015 US Open at Chambers Bay was followed by last year's victory at Oakmont, his first Major, while in February he claimed the world No. 1 ranking.

He believes being a parent has helped him ascend to the top of the golfing heap.

"It just gives you a whole new perspective on things," he said Wednesday. "Where before kind of golf was the most important and now my family is the most important.

"At the end of the day whether I'm having a good day or bad day, when I either see my family or talk to them, whatever, if I was upset or even if I was happy with the way I played, none of that matters.

"Just I'm always happy and excited to be with them."