The 26-year-old and her husband Wayne, 34, are due to welcome their second child within the next month and Frankie has started to suffer from insomnia.
Speaking to OK! Magazine, Frankie said: “I kept waking up at 2am and I just couldn’t get back to sleep, which meant I was really tired looking after Parker [their one-year-old son] and going to work.
“The stomach cramps have made me feel quite uncomfortable but they’re completely normal during pregnancy – it’s another reassuring sign that my baby is getting bigger!”
But Frankie’s not letting her symptoms get her down – she cheered herself up with a night out to see S Club 7 on their reunion tour.
The Saturdays singer and her band mate Rochelle Humes first shot to fame as members of S Club Juniors so it was like a trip down memory lane for Frankie.
She continued: “It was so much fun and I still know all of the words, so I was singing along!
“It definitely brought back memories of my S Club Juniors days because the last time they toured back in 2003, we supported them.
“I have such amazing memories of that show and I’m really glad the guys decided to come back together to perform.”