The pregnant model sparked concern among fans when she tweeted on Tuesday (25 August) that she hadn't felt her baby kick since the crash.
But overnight she assured fans all was okay.
"Thank you everyone for your kind tweets," she said. "I'm spending the night in hospital to monitory my baby. She seems healthy thank God – I'm blessed. Not enough credit is given to the NHS. The midwives and docs at Chelsea and Westminster hospital were amazing. Thank you."
Imogen, 32, had tweeted earlier in the day that she'd been travelling in a taxi with her manager.
She told fans: "Can't believe we just crashed in our taxi. On my side too. Shaking… feel all shocked. We're all okay. The other driver literally drove straight into us sideways."
But later she updated fans to say she was en route to hospital: "Just on my way to see the midwife now to make sure baby is ok cause I haven't felt her kick."
Her manager told The Sun that doctors later gave Imogen and the baby the all-clear.
Imogen and city worker boyfriend Adam Horsley are expecting their second child together. They are already parents to daughter Ariana, two.
Try Reveal 's digital edition On iPhone & iPad. Subscribe now!