EEG polysomnographic study of maturational differences between twins.

The purpose of this pilot study is to asses the effects of multiple pregnancies on the maturation of the developing brain using the polysomnographic EEG recordings. Data from prospectively recorded 10 twin sets, born prematurely (mean 36 gestational week; range 33 - 38 GW) in the Split University Hospital Center, were analysed. We compared sleep architecture parameters in the twins at 37h and 44th postmenstrual age (PMA) with parameters that were expected at that PMA. The same parameters were compared within each twin pair using the Man Whitne test. At first measurement indeterminate sleep (IS) proportion was greater in the first twin than in the second one. The IS sleep proportion was 1.6 fold greater in the first twin (p=0.028), and 1,8 fold less percentage of quite sleep (QS) than the second twin (p=0.054). The length of sleep stages among the twins was similar at the second measurement. Measures of sleep architecture were not significantly different within the twins in second recording. The results of this study obtained on a relatively small number of twins (longer IS and shorter QS in the first twin at the 38th week recordings), showed that the maturational differences among twins exist in utero and shortly after birth, and then disappear until the end of the first month of the postnatal life.