The giant mama panda at the National Zoo in Washington has been artificially inseminated, authorities said. Now they’re crossing their fingers that she becomes pregnant.

Mei Xiang, the 18-year-old giant panda, received two artificial inseminations Thursday, one starting around 2 p.m. and the other around 11:30 p.m. Reproductive scientists and veterinarians have been closely watching her hormone levels in her urine and her behaviors to see if she’s ready to breed.

Giant female pandas have a very short window each year when they can breed so timing it is hard. In fact, they are only in heat for 24 to 72 hours each year.

For the last few weeks, zoo experts have been closely watching Mei Xiang.

Her estrogen levels peaked Wednesday — a sign that she was ovulating and “able to become pregnant,” according to a statement. She was inseminated with semen from the zoo’s 19-year-old male panda Tian Tian.

The zoo experts had tried to see if the two pandas would show signs of being interested in breeding, but they have not ever successfully bred. Again this time, they showed interest only at “incongruent times.”

“Therefore,” the zoo said, “there was no natural breeding this season.”

Pierre Comizzoli, a veterinarian at the zoo, said the two pandas “didn’t show any conclusive behavior” that they were “really interested in each other” so they decided to inseminate her before the window closed.

Giant female pandas are typically pregnant for three to six months. But they can also have pseudopregnancies and show signs of being with cub when they are not. Ultrasounds will be eventually be performed to determine if she is pregnant.

On Friday, zookeepers said Mei Xiang was doing well after the insemination procedure.

“Everything went really well,” said Comizzoli. He said she has recovered and was eating well and in “great shape.”