(Troutdale, OR)  --  Sheriff's deputies say a pregnant woman was killed yesterday when a tree fell on her SUV as she was driving near Troutdale.  Authorities say 30-year-old Kristi Leigh Oliver was westbound on Southeast Oxbow Drive, a few miles south of Southeast Division Street, when the tree fell.  Multnomah County deputies say Oliver died at the scene.  She leaves behind her husband and a three-year-old son.