Ian Ziering and wife welcome daughter Penna Mae

ian-ziering-erin-ziering-second-baby-gi.jpgHow's this for incredible timing? Ian Ziering and wife Erin welcomed daughter Penna Mae Ziering into the world on Thursday, April 25, they've revealed to PEOPLE -- on their first daughter Mia Loren's second birthday!

"We didn't plan it!" Ziering says. "Mia was born a week late and Penna was a week early." Penna arrived at 9:21 a.m., weighing in at 6 lbs., 9 oz. The "Beverly Hills, 90210" alum tells the publication that Mia met her little sister on Thursday night. 'She couldn't wait to meet her. When she saw Penna she said, 'Baby sister!'"

Penna's name, as with Mia's, is inspired by family. Her first name is in honor of Ziering's late father, Paul, while Mae is a shared middle name on Erin's side of the family. The newborn is the fourth generation of women to have it, with Erin's mother, grandmother, and great-grandmother using it as well.

Erin, a nurse, returned home from the hospital on Friday afternoon -- where Mia was ready to welcome them, Ziering says. "She had all her toys lined up and ready to show Penna." Too cute.

Congrats to the happy family!
Photo/Video credit: Getty Images