Background: The introduction of enteral feeds for very preterm (< 32 weeks) or very low birth weight (< 1500 g) infants is often delayed for several days or longer after birth due to concern that early introduction may not be tolerated and may increase the risk of necrotising enterocolitis (NEC). However, delaying enteral feeding could diminish the functional adaptation of the gastrointestinal tract and prolong the need for parenteral nutrition with its attendant infectious and metabolic risks.
Objectives: To determine the effect of delayed introduction of progressive enteral feeds on the incidence of necrotising enterocolitis, mortality and other morbidities in very preterm or very low birth weight infants.
Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2013, Issue 3), MEDLINE (1966 to April 2013), EMBASE (1980 to April 2013), CINAHL (1982 to April 2013), conference proceedings, and previous reviews.
Selection criteria: Randomised or quasi-randomised controlled trials that assessed the effect of delayed (more than four days after birth) versus earlier introduction of progressive enteral feeds on the incidence of NEC, mortality and other morbidities in very preterm or very low birth weight infants.
Data collection and analysis: We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors.
Main results: We identified seven randomised controlled trials in which a total of 964 infants participated. Few participants were extremely preterm (< 28 weeks) or extremely low birth weight (< 1000 g). The trials defined delayed introduction as later than five to seven days after birth and early introduction as less than four days after birth. Meta-analyses did not detect statistically significant effects on the risk of NEC (typical risk ratio (RR) 0.92 (95% confidence interval (CI) 0.64 to 1.34) or all-cause mortality (typical RR 1.26 (95% CI 0.78 to 2.01)). Three of the trials restricted participation to growth-restricted infants with Doppler ultrasound evidence of abnormal fetal circulatory distribution or flow. Planned subgroup analyses of these trials did not find any statistically significant effects on the risk of NEC or all-cause mortality. Infants who had delayed introduction of enteral feeds took longer to establish full enteral feeding (reported median difference two to four days).
Authors' conclusions: The evidence available from randomised controlled trials suggests that delaying the introduction of progressive enteral feeds beyond four days after birth does not affect the risk of developing NEC in very preterm or very low birth weight infants, including growth-restricted infants. Delaying the introduction of progressive enteral feeds results in a few days delay in establishing full enteral feeds but the clinical importance of this effect is unclear. The applicability of these findings to extremely preterm or extremely low birth weight is uncertain. Further randomised controlled trials in this population may be warranted.