Both singers announced they were expecting their first children to fans within a week of each other earlier this month.
Now Perrie has recounted how their manager Samantha Cox – who is also pregnant – was the one who pieced things altogether, which led to the girls sharing their news with one another.
In a TikTok interview, Perrie said: “We were on a work Zoom and we were chatting about things that were coming up in our schedule because in Little Mix we are blocked out two years in advance.
“I was thinking, ‘I won’t be able to do that’.
“I messaged my manager and she called me and said, ‘You’re pregnant’.
“I was like, ’How do you know? And she said, ‘Because I am pregnant’. Then she said, ‘Can I add someone to the call?’”
Perrie continued: “I just heard this voice that said, ‘Perrie! You too!’ And then we just cried our eyes out. We couldn’t believe it.
“What timing! It wasn’t planned.”
Leigh-Anne was first to publicly announce she was pregnant with fiancé Andre Gray on 4 May.
The couple said they couldn’t “believe the dream is finally coming true” as they shared pictures from a stunning pregnancy photoshoot on the band’s Twitter account.
The following week, Perrie also posted a series of beautiful photographs on Instagram to announce she was expecting a child with partner Alex Oxlade-Chamberlain.
She said she was “so happy to be on this wild journey with my soulmate”.
Earlier this month, Little Mix also made history at the Brit Awards when they became the first all-female band to win Best British Group at the ceremony.