Using no fertility treatment, an Australian woman has, nevertheless, conceived quintuplets, that is believed to occur once in 60 million times, states a report.
Melissa Keevers, 27, was inseminated with the sperm of a donor from the United States to conceive the babies, which doctors say have strong heartbeats and are above average size for multiple births.
The incidence of multiple foetuses developing without the use of in-vitro fertilisation is very rare.
"It took me a long time to get my head around what was happening," Keevers told the latest edition of Women's Day magazine, published on Monday.
"But now I've come to terms with it, I'm excited."
Keevers learned she was carrying five babies after going to the doctor in hope of treating her chronic morning sickness.
"During the scan the doctor asked us if we wanted the news, but as he looked pale, we were worried something was wrong," she said.
"He then told us he'd found five gestational sacs meaning, if all went well, we'd have five babies. We can't repeat what we said next."
Keevers and her Irish partner Rosemary Nolan, 21, are already parents to a one-year-old daughter, Lilly, conceived using the same donor's sperm.
The couple say the donor, a college student chosen for his good teeth and eyesight and high IQ, will never know his children because they signed a waiver guaranteeing anonymity.
But the pair have family in Australia and Ireland who are supportive.
"People don't know whether to congratulate us or commiserate," Rosemary told the magazine. "But we think it's a miracle, and couldn't be happier."