The startle reaction of the newborn infant

Startle characterized by a spontaneous or reflecting motoric symptom like brisk, shortlasting and generalized contraction of limb and trunk muscles influence considerably the cardio-respirogram of neonates. The dependence of startles on behaviour, gestational age and postnatal age as well as on levels of blood glucose, calcium and magnesium in serum has been studied in 12 premature infants and in 24 full term neonates by means of polygraphic conditions. The average of 3.6 +/- 3.0 complete startles in premature infants and of 10.6 +/- 8.7 startles in full term neonates per hour non rapid eye movement-sleep, observed on second day after birth, was significantly higher than the frequency of startles in rapid eye movement-sleep measured as 0.6 +/- 0.9 and 1.9 +/- 2.1 complete startles respectively. In an age of 4 weeks there were no complete startles demonstrable in full term neonates and only 0.2 complete startles/h in non rapid eye movement sleep could be observed in premature infants. There was no correlation between frequency of startles and investigated chemical parameters in serum.