The 39-year-old model and her rocker husband Rod Stewart welcomed a 7lb 12oz baby boy named Aiden - a younger brother to their five-year-old son Alastair - at London`s Portland Hospital yesterday (16.02.11), and are "thrilled" at the news.
A representative said: "After the long awaited arrival of their second child, Rod and Penny and proud and thrilled to welcome Alastair`s baby brother Aiden into the world.
"Born February 16, 2011, weighing 7lb 12oz, mother and baby are healthy and blissfully happy."
Model Penny - who turns 40 next month - had to undergo three rounds of in-vitro-fertilisation (IVF) treatment before she became pregnant, and she admitted to crying when she found out.
She said: "I couldn`t believe it. I burst into tears. I called Rod when I was still sobbing. Rod said, `I`m in the middle of a restaurant in Russia, crying.` I kept pinching myself. Neither of us could believe it."
Penny has previously revealed they wanted to have another child because Alistair was desperate for a sibling.
She said: "Rod and I felt blessed already with Alastair but he`s always talked about his friends who had sisters or brothers. He`d return from play dates with my brother`s kids and say, `It`s not fair, they`ve got each other and I have no one.`
"Alastair really wanted a little companion and always said he wanted a baby. I`d tell him it takes three things - Mummy, Daddy and God - and that maybe God thinks we`re so lucky to have him that he wants to give babies to other people who don`t have children. I said we were trying and praying and putting in as much effort as possible to give him a brother or sister."