Pippa, 37, and her husband, James Matthews, welcomed their new bundle of joy on Monday, March 15, at 4:22 a.m. Grace Elizabeth Jane weighed in at 6 pounds, 7 ounces.
"She's perfect, everyone is overjoyed at such a happy arrival," the source added.
The newborn even shares a middle name with her aunt Kate, who was born Catherine Elizabeth Middleton.
In December 2020, rumors swirled that Pippa was had a bun in the oven, but she never confirmed the news herself. Instead, her mom, Carole Middleton, let the news slip while speaking with Good Housekeeping UK.
"I hope to see more of my family than I could last year, including, of course, my new grandchild," Carole said.
Pippa and James, 45, welcomed their son, Arthur, in October 2018; she gave birth in the Lindo Wing of St. Mary's Hospital — the same place where Kate and William welcomed their three children into the world.
Pippa previously gushed over spending time with her young son.
"Starting my son Arthur swimming at four months old has given him confidence and enjoyment in water," she said. "He's now six months old, and swimming is one of our favorite activities. The exercise helps guarantee sound daytime sleeps, and the movement has improved his digestion."
"Water activity is a great form of exercise you can do with your baby!" she added.
Pippa later spoke about how she had to "come up with different activities" to do with Arthur since he was growing up so fast.
"I needed to find something more than just park walks in the pram. Our local baby gym has been a saving grace. It's a big space full of fun, soft objects, playmats, stairs, balls, swings, mini trampolines and more to stimulate and physically engage babies and toddlers," she said.