Why do some women get 'pregnancy lips' like Khloé Kardashian?

The new series of ‘Keeping Up with the Kardashians’ aired on US TV channel E! last night, and ahead of the show Khloé Kardashian issued fans a warning.

“PSA I was pregnant during the entire season of KUWTK,” the 34-year-old told fans, via Instagram Stories.

“Some women get ‘pregnancy lips.’ I was one of them. So my lips look crazy and massive. Trust me I know and I HATED IT!”

Quashing the inevitable rumours that she’d had lip fillers, Khloe explained, “A lot of wild shit happens to your body and face while pregnant. It’s out of our control. Most people don’t have to film during an entire pregnancy so just watch the show and be kind about my growing body and lips.

“Pregnant women should be off limits.”

Agreed, Khloe.

But the Kardashian isn’t the only star who has had to deny she’s had lip fillers while pregnant: while Beyonce was pregnant with her twins she had to release a formal statement explaining her full lips.

What causes pregnancy lips?

From Serena Williams to Jacqueline Jossa, this isn’t the first time we’ve heard of pregnancy lips and they certainly aren’t a new phenomenon, but what actually causes them?

Well, it’s all to do with to body tissue retaining more fluid during pregnancy.

When our pregnancy hormones go into overdrive, bloody vessels dilate which causes the retention up of water.

This is really common in the lower limbs – pregnancy cankles, anyone? – but can occasionally occur in the upper body and face.

“The lips have good surface blood vessels network which give the lips their colour and also are sensitive due to many nerve endings,” Gail Johnson, Education Advisor at the Royal College of Midwives, explained to Made for Mums.

“The pregnancy hormones both increase the volume of blood circulating and relax blood vessels so they are fuller. In addition oestrogen keeps the fullness of lips and of course this hormone is gradually increased all through the pregnancy.”

Are fuller lips in pregnancy anything to worry about?

In short: no.

Pregnancy lips will generally go down by themselves and fluctuate throughout pregnancy.

“While women should not worry about swelling in pregnancy, it could be a sign of pre-eclampsia although it is important to note that most women with swelling don’t have pre-eclampsia,” Gail told the pregnancy specialist website.

“If the swelling occurs suddenly and is not relieved by rest or is accompanied by symptoms such as severe headache, problems with vision, severe pain below the ribs or vomiting, then it could be pre-eclampsia and women should contact their midwife or doctor immediately.”

There you have it: having full lips is just another symptom of being pregnant, and when you put it in perspective, it’s actually one of the more favourable side-effects.

I mean, we’d take a full pout over incontinence or the dreaded morning sickness any day of the week.

Embrace that pout.

Follow us on Instagram and Facebook for non-stop inspiration delivered fresh to your feed, every day. For Twitter updates, follow @YahooStyleUK.

Read more from Yahoo Style UK:

Khloe Kardashian mum-shamed for not supporting her daughter’s neck: ‘That baby doesn’t look comfortable’

Did Khloe Kardashian give birth early and did stress play a part?

Cheating during pregnancy is more common than you think