Date	Event	Description
30 November 2014	New search has been performed	This updates the review "Natural surfactant extract versus synthetic surfactant for neonatal respiratory distress syndrome" published in the Cochrane Database of Systematic Reviews (Soll 2001). Title changed to "Animal derived surfactant extract versus protein free synthetic surfactant for the prevention and treatment of respiratory distress syndrome". Four additional studies added. Outcome of 'necrotizing enterocolitis' added. An increased risk of necrotizing enterocolitis (NEC) is noted in infants who received animal derived surfactant; however, the conclusions are largely unchanged.
27 February 2008	Amended	Converted to new review format.
9 February 2001	New search has been performed	Search of literature through December 2000 led to the inclusion of the following additional trials: Prevention: Hudak 1997. Selective treatment: daCosta 1999, Kukkonen 2000, Ainsworth 2000. Subgroup analyses added, by strategy of surfactant use: prophylactic, or selective treatment of infants with established RDS.
9 February 2001	New citation required and conclusions have changed	Substantive amendment