From a new biography by a People journalist:

Her secret pregnancy with son Trig was nearly uncovered when one of her daughters discovered Trig's prenatal ultrasound scan and confronted Palin with the picture.

But such an ultrasound was never released, even off the record, to the press. Wouldn't that have saved everyone a lot of grief? Then this:

Trig's health was problematic from birth – he was born with a congenital heart defect typically found in half the babies with Down syndrome – but it cleared up on its own without surgery.

Which means a potentially very risky labor and delivery - for the child. One more detail: Levi and Bristol have no immediate plans to wed. The governor's view on sex ed?

"Get beyond the ideal of abstinence."