"I worry that because I've always wanted [kids] so much, as the world goes sometimes, I won't be able to have them, even though I would be able to provide them with such an amazing environment," Fox, 23, says.
The "Transformers" star adds: "And you know, the people who hate kids and don't want kids always end up having 50 of them."
Fox does have a child in her life, however: Kassius, the seven-year-old son of her boyfriend actor Brian Austin Green. Although she and Green (together for five years) recently called off their engagement, they remain together, and share a home with Kassius.
The star -- recently Razzie-nominated for worst actress of 2009 -- confides that "I have no confidence, and because of that I'm always second-guessing myself." For fear of reading harsh reviews of her acting and off-the-cuff comments, she avoids going online.
Save for a high school friend back in her native Florida, Fox counts few female friends -- especially within Hollywood. "I especially don't trust girls in this industry, because it's incredibly competitive, and I'm just not interested," she says.