Bio Sheds Light on Palin's 'Secret Pregnancy'

Sarah Palin kept her pregnancy with son Trig a secret from her girls until late in the game—but almost outed herself when one of her daughters found an ultrasound scan, People reports. This and other tidbits are revealed in Trailblazer, an unauthorized biography of the guv out tomorrow:

• Palin didn't tell her children that Trig had been diagnosed with Down syndrome until the day of his birth.
• Part of the reason why Palin kept mum on the pregnancy? "Not knowing in my own heart if I was going to be ready to embrace a child with special needs—I couldn't talk about it."

• The Palins hired a nanny to help out.
• Daughter Bristol lived with an aunt and uncle during her pregnancy, 40 miles away from boyfriend/babydaddy Levi Johnston, who often made the Wasilla-to-Anchorage drive to take her out and bring her flowers.
• Starstruck Palin once told her hubby she was going to Costco, but detoured instead to a public appearance by Ivana Trump.

(More Sarah Palin stories.)