Rochelle and Marvin Humes conceived their baby during a trip to New York.
The Saturdays singer - who is six months pregnant with her first child with the JLS singer -knew she was expecting a baby within weeks of a romantic getaway to the Big Apple taken by the couple when she took a break from filming the girl band's E! reality show, 'Chasing The Saturdays', but she waited until she was reunited with her spouse before taking a test to confirm her suspicions.
In an interview with Fabulous magazine, she said: ''We were in Los Angeles filming for a few weeks and then we had a few days together in New York, followed by another stint out in LA.
''I knew I was pregnant within a matter of weeks but I wanted to wait till I saw Marvin to be absolutely positive. We did the test together. Marvin was so happy. I think he felt all sort of manly. He was just really excited because he absolutely loves kids and he's brilliant with them.''
The 23-year-old beauty added that Marvin, 27, is preparing for their impending arrival - which is due in May - by reading a handbook on pregnancy designed specifically for men.
She giggled: ''I don't have a maternity book but every night Marvin sits with his chuckling to himself and reading bits out like, 'This week you are going to feel...'
''He carries it around with him everywhere. It's blue and covered with little cartoons of sperm and he absolutely loves it. It's been written by a man so it's full of things like, 'Her boobs will get bigger, which is great, but you can't touch them, which is not great.' ''