Sub HyperlinkToHRef()
Application.ScreenUpdating = False
With ActiveDocument
  While .Hyperlinks.Count > 0
    With .Hyperlinks(1)
      .Range.InsertAfter "<a href=""" & .Address & """>" & .TextToDisplay & "</a>"
      .Range.Delete
    End With
  Wend
End With
Application.ScreenUpdating = True
End Sub