Day is in doubt for next month's US Open and could even skip the looming US PGA Championship at Kiawah Island as he awaits the birth of his fourth child.

Languishing at 62nd in the rankings and without a win in more than three years, Day says he's prepared to miss his first major championship since the 2012 British Open if the baby comes first.

He said his wife Ellie could deliver at any time.

"She's full term on Friday, so, yeah, I'm on call waiting for her," Day said before this week's Byron Nelson tournament in Texas.

"Could come in this week, next week. In the next four weeks it can come.

"If I'm playing golf, whatever, it doesn't matter.

"I just want to make sure that I see the birth of our fourth child."

Day's lone career major victory came at the 2015 PGA Championship at Whistling Straits, while he was runner-up the following year in his title defence.

Without a decent result this year, the Australian would remain outside the world's top 60, which offers automatic entry to the US Open at Torrey Pines, a venue where Day has enjoyed huge success.

He'd still have the chance to return to the top 60 at the Memorial Tournament from June 3-6 on his home course in Ohio.

If not, the 33-year-old has ruled out contesting US Open sectional qualifying.

"I just feel like if I do it that way that in my mind my mindset will say, 'OK, it's fine, you can just go qualify next year' and I'll get used to qualifying instead of going, 'No, I'm not going to qualify','' Day said.

Day has missed consecutive cuts as he continues to work with new swing coach Chris Como.

He would love to play at Torrey Pines, where he has won twice to go with six other top 10s.

But Day missed the cut there by five strokes earlier this year and figures if he misses the US Open it only means more time to spend with his family and work on his game with Como.

"To be honest, it might be a good little time away if the baby does come early or if the baby comes on time," he said.

"But don't get me wrong. In that time I'm still going to be working hard, because I'm not thinking about just Torrey Pines.

"Obviously, I would love to play Torrey Pines US Open because I've had a lot of success around that golf course, but my thing is that I'm starting and I'm just trying to build that confidence.

"I feel like my game is starting to come around nicely and I'm starting to feel good about it."

Australian Associated Press