It started as one surprise pregnancy, then, it turned into four.

A 34-year-old Brisbane woman has given birth to four naturally conceived, identical quadruplet girls in what doctors believe is an Australian first.

Jenitar Na’amoana, who already had four children and was not planning another, became pregnant in what was described as a “one in 15 million” pregnancy, with a single fertilised egg splitting into four.

Na’amoana gave birth by caesarean section at just over 28 weeks at the Royal Brisbane and Women’s Hospital on 14 July, surrounded by a large support team. The girls are Emily, Harriet, Catherine and Alexa, with Alexa named after Dr Alexa Bendall.

“This is unheard of … we don’t think it has ever happened in Australia,” said Bendall, a maternal foetal medicine specialist and obstetrician at the hospital.

“There may have been a couple of cases elsewhere in the world and when I say a couple, literally two.”

Na’amoana was still breastfeeding the youngest of her four children when she was told she was pregnant again. Bendall said the family was stunned when scans showed four babies.

“When they went along and found out they had four babies instead of one they were quite shocked,” Bendall said.

Bendall has cared for Na’amoana since she first learned she was carrying quadruplets.

“They are very special. We are very excited to be able to care for this amazing little family, well big family now,” Bendall said.

“One is named after me which is such a beautiful tribute.”

The pregnancy was considered very high risk, but Bendall said Na’amoana had “taken everything in her stride from day one”.

“We have never seen a spontaneously conceived pregnancy of this type with quads, and she has somehow dodged every complication and risk for both herself and her babies to be here today, with four gorgeous newborn girls,” Bendall said.

The girls are expected to spend an extended period in hospital before going home, but Bendall said their long-term outlook “looks really good”.

The family has set up a GoFundMe fundraiser to help care for the girls, with money going towards medical, travel and everyday living costs, as well as a van “with at least 10 or 12 seats”.

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