Holly Madison is trying to lose 18kg in six weeks so she can get back to her pre-pregnancy weight of 50kg.The former 'Girls Next Door' star - who recently claimed she had "fun" during labour after welcoming her first child, daughter Rainbow Aurora, with fiancé Pasquale Rotella into the world earlier this month - expects to regain her pre-pregnancy figure in no time through exercise and a healthy diet.The 33-year-old blonde beauty model told InTouch Weekly magazine: "We're putting a gym in our house, so I'll be doing yoga, Pilates, and cardio."Holly - who previously starred in 'Peepshow' - also revealed she plans to stick to a healthy diet of green smoothies, coconut yogurt and vegetable stews in order to drop back down to 110 pounds so she is fit in case she is offered another show in Las Vegas.The former Playboy model previously revealed she began thinking about how to lose her baby weight several months before giving birth.She said: "I'll probably start slow with yoga and Pilates. I'm delusionally confident - I feel like I'll be doing some kind of a stage show like a month later. Everyone tells me I'm crazy but that's what I visualise."Holly also revealed she was taking care of her body throughout the pregnancy.She said: "I've been trying to eat healthy for the baby, a lot of green smoothies and fruits and vegetables. And I have pregnancy-yoga and Pilates DVDs that I do as much as I can."