The Calgary Zoo says the premature baby penguin hatched earlier this month is officially "out of the woods" and has been thriving with its foster mom. The hatchling, a king penguin chick, was in danger when its egg broke well before it was time to hatch.

The baby penguin has gone from 185 grams to 440 grams — and that 140 per cent weight gain is double what zoo staff had hoped for, says Alison Archambault, director of marketing, sales and communications.

Archambault said the zoo can officially report that the baby penguin is "out of the woods" and officials will soon move forward with naming the penguin.

The new baby king penguin has been doing well with its foster mom, Diana. (Calgary Zoo)

Earlier this month, the egg was found badly fractured well before the due date. Zoo staff were able to patch it up by using an old shell saved from a Humboldt penguin, and the egg was incubated and monitored around the clock.

The baby penguin was born Aug. 10, right on schedule, and staff were ready with fluids and antibiotics. Foster mom Diana, who has successfully raised two previous baby penguins — Nero and Cleopatra — took to her new charge immediately and fostered the baby through those critical first weeks.

"Thanks to Diana's loving care, our staff and volunteers and the encouraging words people have sent us from around the world, we're happy to advise that our littlest king penguin gained 140 per cent of its body weight, growing from 185 grams to 440 grams — double what we had hoped — in Week 2," said Archambault in a press release.

Our <a href="https://twitter.com/hashtag/LittlestKingPenguin?src=hash&ref_src=twsrc%5Etfw">#LittlestKingPenguin</a> is doing great under the care of foster-mom, Diana. Check out this picture of him/her right as (s)he hatched, with assistance from our Animal Care and Veterinary teams! 🐣 <a href="https://t.co/VivcLddCcE">pic.twitter.com/VivcLddCcE</a> —@calgaryzoo

The baby's parents are 27-year-old king penguin Antoinette and her mate, Louis, neither of whom have produced a baby. A chick from the pair adds much-needed genetic diversity to the North American king penguin population.

Archambault said the zoo will announce the gender soon.