Kelly Osbourne has been diagnosed with gestational diabetes.
The 37-year-old star was diagnosed with the condition as she entered her third trimester of pregnancy.
Kelly - whose symptoms have included weight gain, fatigue and ankle swelling - said: "First of all, gestational diabetes is not your fault.
"At first I thought it was something that I had done. I only got diagnosed with it well into my third trimester, so it wasn't like I developed it as some people get it from the get-go when they're pregnant.
"I got it in my third trimester and, basically, I thought it was something that I had done wrong."
Gestational diabetes is high blood sugar and the issue develops during pregnancy.
Kelly has recently cut out sugar and started watching her carbohydrate intake.
The singer - who is expecting her first child with Slipknot's Sid Wilson - explained to PEOPLE: "This whole pregnancy, I've had no cravings except for sugar, which is something I've never had before.
"The number one thing for me that I realised was taking me down was sugary drinks and it was juice. Because even though I was drinking fresh pressed juice, it still had a lot more sugar than I needed."
Kelly's lifestyle changes have already had a visible impact on her health.
She said: "Overall, my skin cleared up. I don't have to wear any make-up.
"My friends that haven't seen me since I started my third trimester, now that they see me, they're like, 'Whoa. What changed? Your skin is perfect,' and I know that sometimes that has to do with pregnancy, but I had pregnancy acne. I cut the sugar out and it completely went away. I think clearer."