Jessica Alba now understands the science behind why women are sexy.

The pregnant 30-year-old actress gave birth to her three-year-old daughter - her child with husband Cash Warren - in June 2008 and admits since then she has been able to understand female sexuality.

She said: "I was quite shy with it (my sexuality). It wasn't something I embraced until I had my daughter. I saw how incredible and amazing it is to be a woman and to be able to create a life.

"There's a reason why certain areas of the body are desirable -because it all leads to reproduction. There's a science behind it all. It's not just to sell whatever you're selling on a Billboard or a magazine or a movie."

Although she has achieved success and fame because of her stunning looks and body, Jessica insists she is still quite prudish when it comes to how much of her flesh she will flash on screen.

She explained: "At least I'm still covered. I'm wearing as much as a bathing suit. It's not like I'm naked. I'm not terribly comfortable with being in a bikini, but covering up my genitals is different than not covering up my genitals, at the end of the day. I do see a difference in that, to put it really frankly."

Despite apparently regaining her enviable figure after giving birth, the 30-year-old star insists her body has never been the same since she carried her first child.

In an interview in the new issue of Allure magazine, she said: "I can't ever get down to the weight I was before I had Honour. My body's just different. The jeans just sort of zip up differently, and things hang differently. It's a miracle what happens, but you definitely are different afterwards. Unless you're Gisele!"