Effect of Osteopathic Manipulative Treatment on Length of Stay in Preterms

Inclusion Criteria: * preterm infants born at age between 29 and 37 weeks * osteopathic treatment performed \< 14 days after birth * preterms born in the same hospital Exclusion Criteria: * gestational age \< 29, \> 37 weeks; * osteopathic treatment performed \> 14 days after birth; * newborn transferred to/from other hospital; * newborn from to HIV seropositive and/or drug addict mother; * newborn with genetic disorders, congenital abnormalities, cardiovascular abnormalities, neurological disorders, proven or suspected necrotizing enterocolitis with or without gastrointestinal perforation, proven or suspected abdominal obstruction, pre- and/or post-surgery patients, pneumoperitoneum and/or atelectasis.