Megastar Amitabh Bachchan was in celebratory mood as his son and actor Abhishek Bachchan turned 41 on Sunday.

Big B went back to the time when his wife and actress Jaya Bachchan "struggled with her labour" at a hospital here.

Along with a few images of the father and son, Amitabh wrote on his blog: "Once he was at the verge of being born as I had rushed to the Breach Candy Hospital in 1976. Then, he grew and grew to become what he became as in the first pictures.

"I was born, Bachchan ji's (poet Harivansh Rai Bachchan) son. A celebrity even before I knew how to spell the word. Abhishek was born as Amitabh Bachchan's son. A celebrity even before he could find out what it meant."

He said since his father was a known and respected person, there was always "those unwritten behavioural compulsions that were needed to be adhered to... to follow certain social norms, moral and cultural in keeping with the surname".

And Abhishek had to go through the same..."and still does".

Big B "cannot imagine the time passed... those hours at the Breach Candy Hospital... That OPT door opening and Shah, our family doctor, poking his head out of the door and asking - What did you want?'

"His anticipated smile giving away that a son had been born... the champagne bottle opened, the nurse and sisters on duty were given a sip each much against their wishes and protocol but there it was an excitement and the joys of another addition to the family," wrote Amitabh, who also has a daughter, Shweta.

Back to present, as the clock struck 12, the Bachchan family - Abhishek, his wife Aishwarya, Shweta and Big B, celebrated the 'Guru' star's birthday with a barfi cake.

Amitabh even tweeted a black and white photo of his children and captioned it: "A Chelsea win... a Pizza from daughter's favourite, a wishes at 12 and another year for Abhishek gone by. Happy birthday AB."

Other celebrities also wished Abhishek..... Here's what some of them tweeted:

Rishi Kapoor: Happiest Birthday dear AB Jr. Much love and blessings!

Uday Chopra: Happy birthday master Jedi Jworrh Junior Bachchan. The force will be strong with you!

Karan Johar: Love you Ab! Happy Birthday...to the memories and all the best moments we have shared! And to many more.

Anil Kapoor: With an infectious smile and a genuine heart Junior Bachchan you are one of the kindest people I know! Happy Birthday 'Bhaiya'! God bless!

Suniel Shetty: Happy Birthday. Hope you have an amazing 41st. Always wish the very best for you. Stay blessed.

T 2524 - A Chelsea win .. a Pizza from Daughter's favorite .. a wishes at 12 .. and another year for Abhishek gone by ..#HappyBirthdayAB pic.twitter.com/N7sPIV2RUn

— Amitabh Bachchan (@SrBachchan) February 4, 2017