Little Rebecca Chilcott, who was born three months premature on December 30,1999, just missed being a Millennium Baby, but her parents say it's nothing short of a miracle to have her heading off to school on Wednesday.

Rebecca was born at 24 weeks, weighing just 660 grams. After her birth, she lost weight until she weighed 390 grams, just a little more than a can of soft drink.

She was so small that an adult's ring would fit all the way along her arm.

She had to be dressed in dolls' clothes, or clothes specially made for her by her loving grandmother.

"We were praying for a minor disability, we would have been very happy with that because we couldn't believe that a baby that tiny could survive without a disability, but she did," mum Marisa said.

After four months in hospital, Rebecca was a happy, healthy baby, with no signs of the complications her parents had been warned about.

"They will keep an eye on her at school, but she has been fully assessed and re-assessed recently, and she came up well," Marisa said.

Rebecca will join her Kindergarten classmates at St Thomas Aquinas primary school on Wednesday for their first day of "big school". "She'll be fine, it's me I'm worried about," Marisa said.

"She's very excited she's not fazed at all."

The children have already had two half-day orientation sessions to familiarise themselves with their teachers and surroundings at the school.

Most students return to school today, but some schools have opted for new students, whether Kindergarten or Year 7 to start school either earlier or later than the rest of the student body to help them settle in.