Marina and Kevin Krim announced on the Facebook page dedicated to their children that they have welcomed a baby boy.
"We are very excited to share with you that Felix Harrison Krim, all 8 pounds, 10 ounces, and 21.5 inches of him, arrived today. Marina, Felix and all of us are healthy and happy. Thank you all so much for your support!"
Two of the Krim's older children, Lucia (Lulu), 6, and Leo, 2, were stabbed to death, allegedly by their nanny, Yoselyn Ortega, 50.
Ortega has pleaded not guilty to murder.
Their surviving sister, now 4-year-old Nessie, is a big sister again.
The Krim's first announced the pregnancy on their Facebook page and are also holding a benefit to honor their children through their foundation next month.
For more information please visit: https://www.facebook.com/lululeofund