A baby gorilla born over the weekend at the Seattle zoo was delivered via a rare cesarean section, officials said.

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The procedure was performed Sunday at Woodland Park Zoo, on a 29-year-old western lowland gorilla that was five days past her due date, the zoo said in a blog post Tuesday.

The newborn boy weighed 5.4 pounds, over a pound more than the average infant gorilla, the zoo said.

He and his mother, Olympia, are in good health, a zoo official said in the post, though zoo officials remain cautious because the “situation is very fluid and fragile.”

According to the zoo, fewer than a dozen C-sections have been performed on gorillas around the world. None have been done at Woodland.

A team that typically does the procedure on humans performed a C-section on Olympia after an ultrasound showed decreased amniotic fluid and an incompletely dilated cervix, the zoo said.

After the newborn was introduced to the troop, another gorilla that recently gave birth began caring for the baby.

Zoo officials said that wasn’t surprising and that they plan to allow the other mother, Jamanji, to care for both babies while Olympia recovers.