Motherhood is Megan Fox's ''favourite'' thing.

The 'This Is 40' actress gave birth to her first child, son Noah, in September and she is relishing every moment of being a mother.

Megan said: ''I love it. It's my favourite thing that I've ever done so far, so I'm happy with it.''

Megan - who married Brian Austin Green, 39, in June 2010 - also revealed Noah is currently on the verge of laughing.

The 26-year-old actress is sure her heart will ''explode'' with joy when he lets out his first giggle.

She said: ''He's getting to that place where he's smiling and he's almost ready to laugh, and I can't wait for that baby laugh that almost makes you feel like you can fly ... like your heart's going to explode.''

Megan also revealed she loved working with producer Judd Apatow's children Maude, 13, and Iris, eight, who also star in the movie with her and their mother Leslie Mann.

She added: ''Their kids are so well adjusted. They're the best kids and they both have really awesome personalities - especially Iris. She's just a hysterical little ball buster. I think she's super funny, and then Maude is a genius! They are just good kids, which I think is rare for kids that were raised in this industry, so they did a good job.''