BACKGROUND: Congenital and nosocomial infections are important causes of neonatal morbidity and mortality. Maternal transport of immunoglobulins to the fetus mainly occurs after 32 weeks gestation and endogenous synthesis does not begin until several months after birth. Administration of intravenous immunoglobulin provides IgG that can bind to cell surface receptors, provide opsonic activity, activate complement, promote antibody dependent cytotoxicity, and improve neutrophilic chemo luminescence. Theoretically infectious morbidity and morbidity could be reduced by the administration of intravenous immunoglobulin. OBJECTIVES: To assess the effectiveness of intravenous immunoglobulin (IVIG) to reduce mortality/morbidity caused by suspected infection in newborn infants. In secondary analyses to assess the effectiveness of IVIG to reduce mortality/morbidity in those neonates who entered into the studies with suspected infection and who later were confirmed as being infected. SEARCH STRATEGY: MEDLINE, EMBASE and the Cochrane Library were searched in September 2003. The reference lists of identified RCTs, meta-analyses and personal files were searched. No language restrictions were applied. Unpublished information was requested from and obtained from five researchers (Erdem 1993; Gokalp 1994; Haque 1988; Mancilla-R 1992; Shenoi 1999). For this update no new trials were identified but additional information on one trial (Mancilla-R 1992) was obtained in February 2002. SELECTION CRITERIA: The criteria used to select studies for inclusion were: 1) DESIGN: RCT (including quasi-randomized trials) 2) Newborn infants (< 28 days old)3) INTERVENTION: IVIG for treatment of suspected (and in some infants subsequently proved) bacterial/fungal infection compared to placebo or no intervention. 4) At least one of the following outcomes was reported: mortality during initial hospital stay; length of hospital stay; side effects; psychomotor development/growth at follow up. DATA COLLECTION AND ANALYSIS: Two reviewers independently abstracted information for the outcomes of interest and one researcher (AO) checked for any discrepancies and pooled the results. Typical Relative Risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effects model are reported for dichotomous outcomes and weighted mean difference (WMD) for continuous data. NNT were to be calculated for outcomes that showed a statistically significant reduction in RD. For this update we did not calculate the RD and the NNT for the subset of patients, who entered the trials with suspected sepsis and who were subsequently proven to have sepsis. Such estimates are meaningless as the clinician is unaware at the point of starting treatment, whether the infant will have proven sepsis or not. For this update we added the I(2) statistic. MAIN RESULTS: Five hundred fifty three neonates with suspected infection have been enrolled in RCTs to evaluate the effect of IVIG on neonatal outcomes. These studies were undertaken in seven countries. Six studies (n = 318) reported on the outcome of mortality for randomized patients with clinically suspected infection. The results showed a reduction in mortality following IVIG treatment [typical RR 0.63 (95% CI; 0.40, 1.00), RD -0.09 (95% CI; 0.00, -0.17) of borderline statistical significance. Treatment with IVIG (seven trials, n = 262) in cases of subsequently proven infection did result in a statistically significant reduction in mortality [typical RR 0.55 (95% CI; 0.31, 0.98)In spite of different geographical locations of the studies, differences in the mortality in the control groups (range 0% - 43.8%), the use of different IVIG preparations, and different dosing regimens, there was no statistically significant between-study heterogeneity for the outcome of mortality in the two analyses. I(2 )= 0%. REVIEWER'S CONCLUSIONS: The conclusions did not change in this updated review. There is insufficient evidence to support the routine administration of IVIG preparations investigated to date to prevent mortality in infants with gated to date to prevent mortality in infants with suspected or subsequently proved neonatal infection. Researchers should be encouraged to undertake well-designed trials to confirm or refute the effectiveness of IVIG to reduce adverse outcomes in neonates with suspected infection. Such a trial is currently ongoing in the UK and Australia (Brocklehurst 2001). The sample size is 5000 neonates and as of September 2003 more than 600 patients have been enrolled.