What is a simile used to describe motherhood?

“She has her fingers curled tightly around his forefinger and I have hold of her perfect pink foot, and I feel as though fireworks are going off in my chest." (108)

Anna thinks this quote in her first section of narration regarding her child with Tom. As pregnancy, childbirth, and motherhood are major themes in the novel, this simile describes the pleasure of having a child in a way almost painfully joyful since the reader is already aware of Rachel's inability to start a family with the same man.