Caitlyn Jenner has a new grandchild in her life. One day after the news broke about Kylie Jenner confirming the arrival of her first child with rapper Travis Scott, Caitlyn came forward to express her thoughts on the newest bundle of joy.

Like Kylie and the rest of the Kardashian-Jenner clan, Caitlyn did keep quiet about Kylie's pregnancy until on Monday, Feb. 5. The 68-year-oldtelevision personality took to Instagram to express well wishes for the new mom and posted a throwback photo of Kylie when she was an infant.

"My daughter just had a daughter. It's amazing to be by your side through this journey. She's SO beautiful already. Can't wait to watch her grow. Throwback to my baby, as a baby @kyliejenner," the television personality wrote.

Kylie, of course, replied with a short and sweet comment, "Love you," with a heart emoji.

Kylie's Baby Girl 

Kylie and Scott officially welcomed their daughter on Feb. 1, but the lip kit creator didn't reveal the news until Sunday, Feb. 4. Jenner and Scott's baby girl arrived at 4:43 p.m. local time, weighing in at 8 pounds and 9 ounces.

The 20-year-old took to Instagram to post a heartfelt message confirming the arrival of her and Travis's baby girl.

In the message, Kylie apologized to her fans for keeping her pregnancy a secret for so long and thanked her friends and family for being so supportive. She also shared an 11-minute documentary-style video that followed her pregnancy journey.

Caitlyn isn't the only family member to post a congratulatory message to Kylie. Her mother Kris Jenner also stated how thrilled she was to welcome a new grandchild and for the continued expansion of their family.

Kylie's big sister, Khloe Kardashian, took to Instagram to share a now throwback photo of their matching baby bumps and reminisced on the months they spent as mothers-to-be.

"I'll miss you bumping along with me. Never in a million years did I think we would do this together but it's been that much more special because of it," the 33-year-old wrote.

Khloe is slated to welcome her first child with her boyfriend Tristan Thompson in April.  

Kim Kardashian also shared Kylie's baby news on her official website. The mother of three explained that she was so proud of Kylie and is excited for their daughters to become best friends. Kim and Kylie's daughters are two weeks apart as Kim and Kanye welcomed their baby girl via surrogate on Jan. 15. 

"Mommy Kylie!!! You did it!!! I'm so incredibly proud of the woman you have grown up to be and I know you are going to be the best mom to your new baby girl!" Kim wrote