CREATE TABLE table_54428 ("Congresswoman" CLOB, "State" CLOB, "Date of delivery" CLOB, "Mother's age" FLOAT, "Baby gender" CLOB)

How old was the mother who delivered on December 15, 2008?
SELECT "Mother's age" FROM table_54428 WHERE "Date of delivery" = 'december 15, 2008'
SELECT "Mother's age" FROM "table_54428" WHERE "Date of delivery" = 'december 15, 2008'