Some research: (if the linky works!!)
http://ac.els-cdn.com/S0011393X13000350/1-s2.0-S0011393X13000350-main.pdf?_tid=209c0a76-72b7-11e7-b3f9-00000aab0f6c&acdnat=1501151832_730d9058eeeb8713ae49c6d2e4db9e30
I work in a paeds icu... I use the good old 'under the armpit' digital thermos until kids...