Charlize Theron wants to have a child with her fiancé Sean Penn.

The 39-year-old actress already has three-year-old son Jackson - who she adopted before she was in a relationship with Sean - but now she wants to have a kid with the 54-year-old actor to add more love to their family.

In an interview with Italian magazine IO Donna she was asked if she would like to have another child, Charlize replied: ''Yes. I always wanted to have children.''

Since she began her relationship with Sean in early 2014, the 'Mad Max: Fury Road' star admits she's never been happier, although she gets embarrassed to talk about her the love she shares with him.

She said: ''I am incredibly happy, and lucky. I'm not good at talking about my personal life, but yes, I have to admit: I'm really happy ... Why? Let's start by saying that, in general, you are attracted by people who thinks like you, and have the same interests. If we add that this 'man' that you would like to know everything about is also an old friend of mine, and that our conversation has gone on for 18 years ... Now that I have passed the age of 20, I don't have to prove anything to anyone just because I show myself in a certain way.

''Now I am happier, wiser and definitely more at peace with myself. But I wouldn't like to remain always the same. I like to change and evolve.''

The couple are expected to wed this summer. While the nuptials will be Charlize's first, Sean was previously married to Madonna from 1985 to 1989 and Robin Wright from 1996 to 2010.

Sean and Robin have two adult children, daughter Dylan and son Hopper, together.