New Zealand children have been part of a study that's undone years of misconception..

It's debunked earlier studies claiming long effects for IVF babies - who are more likely to be born prematurely, with a low weight.

But new research shows the health effects are gone by 10 to 13-years-old.

Co-author Dr Caroline Walker says the technology has been around 40-years and is only getting better.

She says parents can be reassured children conceived via IVF won't have long term health implications.