The popstar was accompanied by her on/off boyfriend Jason Bell, once again sparking rumours that he could be her baby's father, as she left the airport in a tightly wrapped black coat.
Nadine announced she was pregnant in August by posting the news on Instagram with a snap of herself and the words 'I'm having a baby' underneath.
As Nadine has kept quiet about her love life in recent years, the identity of her baby daddy has not been confirmed, but it was rumoured she had reunited with her ex-fiancé, American footballer Jason, back in March.
The pair's relationship ended after a year's engagement in June 2011.
Nadine will be the first of her former Girls Aloud bandmates to become a mum.