Professor Green and his girlfriend Karima McAdams are expecting their first child together.
The rapper, 37, announced the news with a photo showing him in the bath and actress McAdams, 35, sat on the floor looking down at her baby bump.
He wrote: “And then, all of a sudden everything is different. It all makes sense.”
The east London-raised musician, real name Stephen Manderson, went on to explain that it had become impossible to hide her pregnancy from the public.
Writing about his emotions, he added: “I’ve been overwhelmed with excitement, admiration and curiosity ever since we found out. I’m excited about meeting you. Holding you. Teaching you. Learning from you.
“Never have I admired anyone as much as I have your mamma. She’s nothing short of remarkable, remarkable in fact is an understatement.
“To see the body change in such a way is fascinating, incredible, unbelievable, amazing, ASTOUNDING. Weird. Ridley Scott had to get his inspiration from somewhere…
“I feel a bite useless sometimes, pedestrianised; left to spectate from the sin bin as each phase plays out. It’s humbling; never do our strengths as men compare to that of a woman. I’m awestruck. Subservient (albeit reluctantly at times).
“I’m curious about everything to come; about who and how you’ll be, what you’ll look and sound like… and who’ll be the stricter parent.
“A friend told me the best thing you can do for your own anxiety is to have a child. It sort of made sense at the time, it doesn’t anymore; THIS HAS BEEN WILD.
“My understanding of mortality and just how fragile life is have grown exponentially.”
The music star signed off by wishing his fans a “very joyous and healthy 2021”.
McAdams shared a photo of them kissing on her own Instagram account and wrote: “So my mate and I are procreating.”
She added: “It’s been tumultuous, a process this delicate has been hard for this heavy handed Berber brute and I’m sure there are more surprises to come but I feel lucky- I REALLY loved biology and now I’m my own walking case.”
The couple reportedly began dating in the summer of 2019.
Love Island host Laura Whitmore and singer Ella Eyre were among those who sent their congratulations.
Eyre wrote: “Remarkable is a HUGE understatement @karimamcadams. so proud and happy for you both my favourite future parents !!! Can’t wait to see you be a soppy lil shit all the time.”