In a world first, two cheetah cubs conceived through in vitro fertilization have been born. Their surrogate mother, Isabelle (Izzy), gave birth to the cubs on February 19 at the Columbus Zoo and Aquarium, Ohio. Hailed as a scientific breakthrough, the successful IVF birth could play an important part in conservation efforts for the cheetah, which is red-listed as “vulnerable” by the International Union for Conservation of Nature (IUCN).

This was only the third attempt by scientists to carry out this procedure in cheetahs, where all previous efforts were unsuccessful. In other big cat species, IVF is also rare, with the birth of three tiger cubs reported back in 1990. Therefore these births, made possible by a partnership between the Columbus Zoo, the Smithsonian’s National Zoo and Conservation Biology Institute (SCBI), and Fossil Rim Wildlife Center in Texas, are groundbreaking in the field.

The biological mom of the cubs is Kibibi, a 6.5-year-old cheetah, whose chances of having children is low. Her eggs were fertilized in a laboratory with sperm previously taken from a male cheetah living in a different location. The embryos were then implanted into 3-year-old Izzy’s womb, where they developed into fetuses. This process was also carried out with different egg and sperm donors, implanted into a different surrogate’s womb (which happened to be Izzy’s sister Ophelia), but it was unsuccessful.

Throughout Izzy’s 93-day gestational period, the team carried out multiple pregnancy checks. Due to the close bond between the Zoo staff and Izzy, she had been voluntarily trained to allow ultrasounds, X-rays, blood draws, and other medical procedures, preventing the need for extensive use of anesthesia during her pregnancy.

“We knew that Izzy was pregnant at five weeks by ultrasound and we continued to collect ultrasound data throughout her entire pregnancy. It was a remarkable opportunity and we learned so much,” Adrienne Crosier, cheetah biologist at the Smithsonian Conservation Biology Institute, one of the scientists who performed the embryo transfer, said in a statement.

Izzy’s care team put her on a 24-hour watch a few days before her due date, ready to be on hand if necessary. They have continued to monitor both Izzy and her cubs since birth, with the first-time mom providing great care to the cubs; one male currently weighing in at 480 grams (16.9 ounces) and the other a female who weighs 350 grams (12.3 ounces).

The feat is of huge importance in conservation efforts of cheetahs, as it can be used to help maintain genetic diversity in the decreasing population. Kibibi, the biological mom, has valuable genes that were at risk of never being passed on, whereas Izzy’s bloodline was already well represented in the cheetah’s genetic registry. Wild cheetahs could also benefit from this technique.

In their native range of Africa, threats to the cheetah population, including habitat loss and fragmentation, conflicts with livestock and game farmers, as well as unregulated tourism, have left only 7,500 individual cheetahs geographically separated. This genetic “bottlenecking” raises the likelihood of interbreeding, meaning that cubs are more susceptible to diseases as well as other physiological impairments – a huge problem when the infant mortality rate is already as high as 83 percent.

 Therefore, increasing the genetic diversity of the cheetah population through IVF and embryo implantation could spell a “big win for the cheetah.”

“The first thing we had to do is show that this technique works,” Dr Randy Junge, the Columbus Zoo’s vice-president of Animal Health said in a statement. “Then we have to become proficient in it, so we can do it efficiently and reliably. With experience, we may be able to freeze embryos and transfer them to Africa.”