I think that if you cut the cord before the placenta has been born then you potentially interfere in a process that we don't actually fully understand.  There is a two way process of exchange happening.  Maybe Jaundice is  more common when the cord is cut prior to birth of placenta because only one part of the process is complete.  Anecdotally it appears that if the placenta is born before cutting the cord jaundice is far less.   When recording blood results Normal is considered to be the blood result with early intervention.  It is far more likely that the "high" result with a physiological third stage is really a normal result.