Megan Fox has admitted she's had three breast enlargements, but is paranoid about going under the knife again.

The 37-year-old star has told how she first had her "boobs done when (she) was 21 or 22,” after she starred in her first Transformers movie.

She added, “I had (my breasts) redone after I was done breastfeeding my kids, because I don’t know where they went but they went."

She continued, "I had to have them redone very recently, because the first set, I didn’t have enough body fat to disguise…the rippling of the implant, I had to switch them out to this set.”

Megan, who is engaged to Machine Gun Kelly, said she deliberately chose a bigger size this final time.

"I was like, ‘I better wake up with the biggest boobs you can fit in my body.’ And that is what he said he did. And they're not even that big. They're a 32D, which is not that big. They just look big on my body because my body is tiny."

She revealed how despite having several surgeries, her “body does not react well to general anaesthesia,” so it’s a “very big deal” for her when she has a procedure done.

“All my doctors have to meet with me before, and have to tell me if they’ve seen any omens, if they saw any owls, crows, if anyone stepped on a spider, if there were any dead insects,” she said. “My doctors have to go through this with me, because I’m very afraid of dying under general anaesthesia. I don’t take surgery lightly, and therefore I have not had many of them because of that.”