The 38-year-old is mum to Ethel Mary, 11, and Marnie Rose, nine, with ex-husband Sam Cooper.
"I never really had a strategy when it comes to career, but yes, my children ruined my career. I love them and they complete me, but in terms of pop-stardom, they totally ruined it," said Allen, who rose to fame with hits Smile and The Fear in the mid-Noughties.
The singer released her latest and fourth album No Shame, in 2018, and married David Harbour in 2020. "It really annoys me when people say you can have it all because, quite frankly, you can't," she said.
"Some people choose their career over their children and that's their prerogative, but my parents were quite absent when I was a kid.
"I feel like that really left some nasty scars that I'm not willing to repeat on mine. I chose stepping back and concentrating on them and I'm glad that I've done that."
It's a conundrum many women have to weigh up, because, pop star or not, having children does have a huge impact on women's careers - far more than men's on the whole, statistically.
Research commissioned this month by the charity Pregnant Then Screwed found that the 'motherhood penalty' is worsening - with UK mothers earning 4.44 pounds ($A8.60) less an hour than fathers in 2023.
The analysis - which compared data from January to March 2023 with the same period in 2020 - found that the median hourly pay was 18.48 pounds ($A35.80) for fathers compared with 14.04 pounds ($A27.20) for mothers, growing by 93p ($1.74) an hour since 2020.
But it's important to note that while this gap is largely reflective of the fact that many mothers take a year-long maternity leave, go back to work part-time, become a stay-at-home mum for a period, or simply feel unable to progress at work because there's so much going on at home, it isn't as simple as saying this is a 'choice' women make.
As Joeli Brearley, CEO and founder of Pregnant Then Screwed, suggests, they aren't choices made in a vacuum - they are made against a backdrop of bias, discrimination and legislation.
"The notion of choice is a complete misnomer," she says.
"It's just not the reality at all. We've been polling mums and asked stay-at-home mums if they'd like to work, and they've said yes. We asked working mums if they'd like to stay at home with their children, and the majority said yes.
"We know that in other countries where you have a completely different legislative framework, the women make very different 'choices' - in inverted commas. Because it's not a choice. It's influenced by so many factors" - like the policies at your workplace, childcare costs, what your family and friends do and think.
"They're not real choices that anyone is making, [it's] the best option within a limited spectrum of choices."
The phrase 'You can't have it all', that Allen alludes to, may feel infuriating, because why should women have to choose between a career and a family, when men don't usually have to?
But Brearely says: "I think it's absolutely true. I'm glad she's said it. As a woman, you can have it all, but not at the same time."