On Monday, Teigen updated her fans from Cedars-Sinai Medical Center in Los Angeles, where she is receiving treatment.
Alongside a throwback photo of her looking sullen on New Year's Eve, the model wrote: “Hello from hospital. About to have my second blood transfusion which truly truly truly sounds more dramatic than it is.
“It’s an IV, but instead of fluids, the blood of some kind human being out there.”
She went on to reassure her 31.3m followers that both she and her baby “are completely fine”.
“Just missing the little things like walking...cooking...playing with the other buttbutts. Came across this little gem from ringing in 2020. It all makes sense now!”
The model, who already shares two children with husband John Legend, posted a series of videos from her hospital bed on Sunday, explaining the bleeding issues had been happening for a “little less than a month”.
“We're talking more than your period, girls, but definitely not spotting,” she explained. “A lot of people spot and it's usually fine. But mine was a lot.”
She told fans her baby is “so healthy” and “growing stronger” than her other children, four-year-old daughter Luna and two-year-old son Miles, at the same stage.
“He moves a lot,” she added. “He's moved so much earlier than they ever did. He's like a roly-poly. We have like a million great pictures of him. He's just so different than they were.
“So he's so strong and I'm just so excited for him because he's so wonderful and just the strongest little dude, so I can't wait for him.”
It’s a hospital, john pic.twitter.com/thyf2TevGN— chrissy teigen (@chrissyteigen) September 28, 2020
Writing on Instagram, the 34-year-old said: “I didn't really know that bed rest was in bed. I honestly thought bed rest was you have to really, really relax, stay home. I thought it could be couch rest.”
“It’s a bit of a difficult pregnancy,” she continued. “I feel good though. I will say I’m probably being punished for talking so much about how great the first two went.
“I was like, ‘Oh yeah, pregnancy’s awesome!’ But now I get it. I get anyone that thinks it’s not so awesome, but very happy to be carrying this baby.”
Teigen and Legend confirmed they were expecting their third child together last month.
The couple made the announcement through Legend’s latest music video for the song “Wild!” by featuring a closing shot of Teigen cradling her growing baby bump.
According to the NHS, bleeding during pregnancy is “relatively common and doesn't always mean there's a problem – but it can be a dangerous sign.”
You should call your GP or midwife if you have you have any bleeding from your vagina during pregnancy.