Optimizing enteral nutrition (EN) is challenging in extremely preterm infants due to feeding intolerance that relates to the functional gastrointestinal immaturity. Early feeding is a safe way to promote postnatal gastrointestinal maturation and, when compared with delayed enteral feeding, provide benefit, such as reduced time to full enteral feedings (TFF) and number of parenteral nutrition (PN) days. Failure to develop oral feeding competence often leads to growth failure, longer hospital stays, dependence on PN and its complications, and influences long-term growth and developmental outcomes. Feeding with human breast milk has a protective effect against necrotizing enterocolitis (NEC) compared with formula, whereas feeding intolerance is one of the early signs of NEC. Delayed passage of meconium is a risk factor for feeding intolerance in preterm very low birth weight neonates and specific meconium microbiota characteristics have been linked to increased risk of NEC. This randomized controlled trial (RCT) aims at evaluating the effect of regular intestinal lavage using normal saline on the TFF and severe complications such as NEC and sepsis, in extremely preterm infants. Investigators aim also to follow children´s neurological development until 5,5 years of age. The study will include one intervention group of 100 subjects that will receive regular rectal washout with normal saline and equal number of control subjects, treated according to current routine. The trial is preliminarily estimated to last between year 2018 and 2022. Investigators will monitor closely for possible adverse events. The results are going to be published in reviewed medical journal.