The 32-year-old and his wife, Monica, are expecting their new baby the day before the World Cup final gets under way in South Africa, by which time the Kiwis are almost certain to have been eliminated.
However, the New Zealand captain admits a premature birth would see him fly straight back to England and miss the tournament.
"If it comes [the birth] a couple of weeks early, it could be interesting," he told the Dominion Post.
"If it did come early, I'd have to get on the plane and head straight home. There's nothing on this earth that would stop me from being there at my child's birth.
"Obviously, I've majorly got my fingers crossed and I hope it doesn't happen."
New Zealand manager Ricki Herbert says he would not stand in his captain’s way should he want to return home early.
"There are always personal things in people's lives that are important," he added.
New Zealand will meet Slovakia, Paraguay and Italy in Group F of the tournament.
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