But as the tiny 13-week-old Milton baby sleeps at night, her parents can relax - for the first time in her short but dramatic little life.
The baby, who was 12 weeks premature, has just returned home after spending the first three months of her life in Dunedin Hospital's neonatal intensive care unit.
Because of her sudden and early arrival, she has a heart monitor attached to her at nights, but Millie has also been fitted with a St John Lifelink alarm.
The alarm is designed to give parents extra reassurance that should something go wrong, they simply have to push a button and an ambulance will be sent immediately.
For Millie's mother Kate Flett, the alarm is a god-send and provides peace of mind.
"We're not sure how long Millie will have the alarm but possibly around four months.
"It's great to have as it gives us some peace of mind in case something goes wrong and I know the ambulance is just around the corner."
The youngster, born on December 29, has been sleeping soundly at nights.
Her parents say they can finally relax a little after a hectic start to the year in which Ms Flett lived at the hospital and Millie's father, Simon Scott, travelling to Dunedin daily.
St John Lifelink representative Mandie Lungley said she was thrilled St John could help a baby born prematurely.
Although medical alarms were often associated with elderly people, they could provide life-saving care for people of all ages.
