The 34-year-old has revealed she discovered she and husband Justin Scott would become parents for a second time just weeks after celebrating their wedding in January.
She told Hello!: “We knew soon after we got married that we’d be very happy for baby number two to come along. When I first met Justin 14 years ago, I told him I wanted four children... We’re both over the moon.”
The couple have a son Bobby who is 21 months old.
She married Scott, a property developer and former member of boy band Triple 8, during an intimate ceremony in Barbados.
Her former Girls Aloud bandmates Cheryl and Nicola Roberts were her bridesmaids and they were also among the first to find out she was expecting again.
“Before I had even taken a test, I knew it instinctively,” she said.
“I wasn’t suffering from morning sickness but telltale changes in my body made me certain I was expecting. When I took a home test early one morning to make sure, it confirmed what I’d already sensed. I was thrilled. The first thing I did was to wake up Justin and tell him, ‘You’re going to be a daddy again!’”
She said she feels more “chilled” during this pregnancy because she knows what to expect.
Walsh also revealed that Cheryl is “so happy for us”, adding: “When Cheryl came over to visit, I couldn’t keep my pregnancy a secret any longer. She was so happy for us and thinks it’s great to keep our family growing and that there will be a small age gap between Bobby and the new baby.”
The couple opted not to find out the sex of their baby at the 12-week scan as they want the baby to be their “Christmas surprise”.