Late preterms: are they all the same?

Very preterm infants (VPT) and, especially extreme low gestational age (ELGA) preterms, often on the threshold of viability, make the headlines of both, the scientific as well as the popular press. However, all together they represent between 1 and 2% of all livebirths. Late preterms (LPT) those born between 34/07 and 36/06 weeks, on the other hand, may account for up to 80% of all preterms and for some 5-8% of all births. Although mortality is low they are prone to increasing neonatal morbidities posing a considerable medical, financial and psychosocial burden. In the last years, for many reasons, LPT appear to have increased considerably throughout the western world. But are LPT neonates all the same? In spite of overlapping gestational ages (GA) LPT may behave quite differently depending on circumstances surrounding their pre- and postnatal events. We can identify three different classes of LPT neonates: spontaneous late preterms (SpLPT) born in the absence of previous maternal illnesses and/or pregnancy related disorders; Induced LPT (IdLPT) due to maternal/fetal complications and those babies being born after 34-week gestation from postponed delivery at an earlier GA (PtLPT) - and they are quite different babies, with different behavior, despite a common and same gestational age.