The Washington, D.C. zoo welcomed the baby panda on Aug. 21.


It's a boy!

On Monday, the Smithsonian's National Zoo confirmed in a press release that Mei Xiang's six-week-old panda cub is a boy. The discovery was made by Smithsonian Conservation Biology Institute (SCBI) scientists.

According to the release, zoo veterinarians obtained a swab from the baby panda's cheek for DNA analysis after his first veterinary exam on Sept. 19. Since male and female panda cubs appear similar at birth, a genetic test was the most accurate way to determine the cub’s sex.

The swab was brought to SCBI’s Center for Conservation Genomics, where scientists sequenced a short fragment of the zinc finger protein gene. From there, scientists determined that the swab sample taken by the zoo’s veterinarians had both X and Y chromosomes — confirming that the cub is male.

Zoo veterinarians also offered an update on the cub, saying in the release that he "appears to be healthy and strong."

During a exam conducted on Oct. 1, the cub weighed in at 3.6 pounds and measured 14 inches from nose to tail tip, while his abdominal girth was 12.5 inches. Both of the cub’s eyes are starting to open.

Mei Xiang, 22, became the oldest giant panda to give birth in the United States — and the second oldest in the world — when she welcomed her cub on Friday, Aug. 21, at 6:35 p.m. after more than three hours of labor.

"Mei Xiang picked the cub up immediately and began cradling and caring for it," the zoo said in a news release at the time. "The panda team heard the cub vocalize and glimpsed the cub for the first time briefly immediately after the birth."

Mei Xiang was artificially inseminated on March 22 with frozen semen collected from her mate, Tian Tian, according to the zoo. She began exhibiting behaviors consistent with pregnancy in late July.

The National Zoo confirmed that Mei Xiang was pregnant earlier in August when veterinarians found fetal tissues in an ultrasound. At the time, zookeepers said they saw "clear images of a developing skeletal structure and strong blood flow" in her womb, calling the discovery a "significant opportunity" as female giant pandas can only become pregnant for 24 to 72 hours each year.

In addition to her new cub, Mei Xiang is also mom to Tai Shan, 15, Bao Bao, 7, and Bei Bei, 5.

Tai Shan, Bao Bao, and Bei Bei currently reside in China as a part of the zoo's cooperative breeding agreement with the China Wildlife Conservation Association.

This story originally appeared on People.