Backgrounds Very preterm birth and very low birth weight (VLBW) is associated with adverse neurodevelopmental outcome. Many very preterm/VLBW infants develop perinatal infections. This quantitative meta-analysis summarizes studies evaluating the effect of perinatal infections on neurodevelopmental outcome in this population.

Methods We searched Medline, PsychInfo, EMBASE and Web of Knowledge for studies on infections and neurodevelopmental outcome measured with Bayley Scales of Infant Development 2^nd edition (BSID-II) scores in very preterm/VLBW infants. Two authors independently reviewed, rated and abstracted data from each article.

Results This meta-analysis includes 18 studies encompassing data on 13.755 very preterm/VLBW infants. Very preterm/VLBW infants with perinatal infections have poorer mental (–0.25 SD, p<0.001) and motor development (–0.37 SD, p<0.001) compared to very preterm/VLBW infants without infections. Mental development is most impaired by necrotizing enterocolitis (NEC, –0.40 SD p<0.001) and meningitis (–0.37 SD p<0.001). Motor development is most impaired by NEC (–0.66 SD p<0.001). Chorioamnionitis did not affect mental or motor development (–0.05 SD, p=0.37 and 0.19 SD, p=0.082).

Conclusions Postnatal infections have detrimental effects on mental and motor development in very preterm/VLBW infants. This effect adds up to the well-known detrimental effect of prematurity and highlights the importance of infection prevention in these vulnerable infants.