There are just two northern white rhinos left in the entire world - and they're both female. But now, their species has a chance at survival, as researchers have for the first time achieved an IVF rhino pregnancy.

BioRescue Project, a reproduction technology nonprofit focused on saving threatened species, announced on Wednesday that the company saw the "world's first successful embryo transfer in rhinos." Achieving the feat, the company says, "paves the way for saving the northern white rhinos from extinction."

White rhinos as a whole have seen declining numbers, largely due to poaching, the International Rhino Foundation says. There are two subspecies - the southern white rhino and the northern white rhino - the latter of which is considered extinct in the wild. Just two northern white rhinos remain in the world and reside in a 700-acre enclosure at Kenya's Ol Pejeta Conservancy, where they have 24-hour armed security.

The embryo was not placed in one of the northern white rhinos. Instead, a southern white rhino embryo was produced and transferred into a southern white rhino surrogate mother at the conservancy. The embryo was placed on Sept. 24, BioRescue Project said, adding that they confirmed a pregnancy of "70 days with a well-developed 6.4 cm long male embryo."

"The successful embryo transfer and pregnancy are a proof of concept and allow to now safely move to the transfer of northern white rhino embryos," the group said on Facebook, "a cornerstone in the mission to save the northern white rhino from extinction."

BioRescue uses an in-vitro approach called advanced assisted reproduction technologies (aART), which the group says is "the only option to create offspring for the northern white rhinoceros." The group previously said that it performed 65 aART procedures from 2015 to 2022, and in a study published in the scientific journal "Reproduction," they found that aART, which also includes retrieving immature egg cells from animals' ovaries, "proved to be a guarantee for successful production of white rhino embryos."

The group said its use of the procedures did not produce any indications of adverse effects on the health of animals subject to the procedures. Instead, they said there were "clear indications of health benefits."

One of the northern white rhinos, Fatu, had a pathological cystic ovarian structure decrease from 50 milimeters to 15 milimeters in diameter over the course of three years and 10 egg retrievals, the group said, adding that they have not found any signs of the procedures hampering natural reproduction methods among animals.

"The health and wellbeing of the southern white rhino surrogate mother Curra and male southern white rhino teaser bull Ouwan was carefully monitored throughout the process," the Ol Pejeta Conservancy said on Instagram. "Both healthy rhinos showed no complications or adverse effects of the procedure."

However, in November, both parent rhinos were found dead, they said.

"It was discovered that extremely heavy, climate change-related rains led to a flooding of the surrogate enclosure and set free dormant Clostridia bacteria spores which had infected and killed both rhinos," the conservancy said. "...Quick action prevented any further rhino deaths."

While researchers continue to monitor the developing embryo, the conservancy said the hope is to eventually complete an embryo transfer with a northern white rhino, allowing scientists to save the species.

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