The former Girls Aloud singer announced she is having a baby last week and because the baby was unplanned she took multiple tests to check she was definitely expecting.
A friend of the pop beauty told heat magazine: "Nadine totally freaked out when she realised she was pregnant. It wasn't planned, but she's never been so happy. She was so shocked, she ended up taking three pregnancy tests, just to make sure."
Nadine has been living in Los Angeles for the last few years and has a number of business interests in the US.
But the 28-year-old star wants to return to her hometown of Derry in Northern Ireland to give birth so she can have all her family with her.
The pal added: "She wants the baby to be born in Ireland, but admits that it probably won't be possible and she'll have to have it in the States.
"She says she's already getting a cute little bump and she thinks it's a girl, because she is 'physic about these things'."
Nadine is yet to reveal the identity of the father but is believed to be expecting her baby with her
former fiancé Jason Bell, a now-retired NFL player who she was in a relationship with for three years.