The mother of the only giant panda twins in the United States may soon deliver a second set of twins, Zoo Atlanta said on Tuesday, capping off an eventful month for lovers of the fluffy black and white bears across the globe.

Three years ago, mother bear Lun Lun gave birth to female cubs Mei Lun and Mei Huan, who are still at the Georgia zoo but could be returned this fall to China, which owns them, zoo spokeswoman Rachel Davis said.

An ultrasound on Monday confirmed that Lun Lun, who turns 19 years old on Thursday, is once again pregnant with twins, the zoo said.