Crossword clues for First birthday. 3 lettersAnswerClueONEFirst birthday.POEHis mystery admirer didn't appear graveside to toast his birthday in 2010 for the first time since 1949AGEONEWhen a tot gets her first birthday partyORIGINALSKINFirst birthday suit?NANAFirst birthday party attendee, oftenAGEONEThe year following a first birthdayONESIEFirst birthday suit, perhapsADAMSThe first president to occupy the White House, which celebrated its 200th birthdayADALOVELACEMathematician believed to be the first computer programmer (she had a Google doodle devoted to her 197th birthday this past Monday)