There's a perfectly reasonable explanation for why Beyonce's famous pout has changed.

There’s been a swarm of rumours from the Beyhive that the queen herself may have been stung… on the mouth.

Beyoncé’s famous pout has been under scrutiny from fans this week after the superstar posted a series of selfies on her website over the weekend.

Her lips are looking a little fuller, you see, with some speculating a little filler could be to blame.

Did #Beyonce get her lips done or is it just lip liner? Or better yet pregnancy swelling? ???????????? Newly released Bey pics spark rumors that she’s possibly had some work done ???????????? #LetsTalkAboutIt www.honeygerman.com

A post shared by HONEY GERMAN (@honeygerman) on Mar 19, 2017 at 6:12pm PDT

It’s possible the 35-year-old may have had some work done or, far more likely, she went a little heavy on the lip liner that day.

And in fact, the answer could be one of mere biology gone mad.

For those who’ve forgotten (HOW THOUGH?), the mother-of-one announced last month she’s soon to be a mother-of-three, in a pregnancy photo shoot for the ages.

And you know what happens to pregnant ladies (yes, even fancy ones), occasionally their lips swell up.

In 2015, when Kim Kardashian was pregnant with Saint, she was stormed with similar 'enhancement' accusations because of her noticeably fuller lips.

And while her family history may have fuelled that particular bout of commentary, the reality star maintained her look was au naturale.

Pregnancy lips ????

A post shared by Kim Kardashian West (@kimkardashian) on Aug 25, 2015 at 10:49am PDT

"Pregnancy lips," she explained on her Instagram.

'Could it be?' we asked quite literally, after reaching out to Dr Jodie Silleri, a General Practitioner and Cosmetic Physician, for clarification.

“It’s absolutely true that [pregnancy] can cause swelling of the lips. It is a real phenomenon,” she told Mamamia at the time.

As a woman's hormonal balance changes during pregnancy, she may experience fluid shifts, particularly around the second or third trimester.

In fact, around a quarter of pregnancy weight gain is tied to fluid retention.

“More commonly we retain fluid in the legs and the ankles and feet, but we can also retain it in the hands and the face. As a doctor, I see women who are pregnant with swollen lips,” Dr Silleri explained.

Hello Bump: You're pregnant, now what? Post continues... 

The additional fluid softens the body so it expands easily as the baby develops and helps prepare the pelvic joints and tissue for delivery.

Funnily enough, Dr Silleri said the lips of women who've previously had lip injections appear to swell “proportionally more” during pregnancy than those who haven't.

“That’s just my anecdotal observations … I don’t know exactly what the mechanism behind that is, it could be some remaining hyaluronic acid that’s drawing the water to it,” she said.

So in conclusion, in addition to the sweating, bizarre hair changes, nausea, food cravings and tummy troubles, some lucky mums-to-be may also look forward to a pop star pout.

As you were, Internet.