The British star announced in November (12) that she is expecting her first child with her husband, JLS hunk Marvin Humes, and the baby is due later this year (13).
Humes admits she was desperate to keep her happy news a secret for as long as possible but her bandmates noticed the tell-tale signs within weeks.
She tells British magazine Fabulous, "I was terrified about getting to three months. But they totally busted me. I felt so sick, I kept disappearing to the loo, and there's only so many times you can have food poisoning.
"My mum told me if I was offered a drink just to accept and hold it and not drink it. I kept doing that and I'd seen Una (Healy) raising her eyebrow at me. In the end, I had to admit it. They shrieked, but in a quiet way because they understood I wanted to keep it secret."