Outcomes at 7 Years of Age of Former Very Preterm Neonates with Repeated Surfactant Treatment for Prolonged Respiratory Distress in the Neonatal Period.

This study aimed at evaluating the 7-year outcomes of 118 very preterm newborns (VPNs, gestational age = 26 ± 1.4 w) involved in a randomized controlled trial. They presented neonatal respiratory distress (RDS), requiring ventilation for 14 ± 2 days post-natal age (PNA). A repeated instillation of 200 mg/kg poractant alfa (SURF) did not improve early bronchopulmonary dysplasia, but the SURF infants needed less re-hospitalization than the controls for respiratory problems at 1- and 2-year PNA. There was no growth difference at 7.1 ± 0.3 years between 41 SURF infants and 36 controls (80% of the eligible children), and 7.9% SURF infants vs. 28.6% controls presented asthma (p = 0.021). The children underwent cognitive assessment (WISC IV) and pulmonary function testing (PFT), measuring their spirometry, lung volume, and airway resistance. The spirometry measures showed differences (p < 0.05) between the SURF infants and the controls (mean ± standard deviation (median z-score)) for FEV1 (L/s) (1.188 ± 0.690(-0.803) vs. 1.080 ± 0.243 (-1.446)); FEV1 after betamimetics (1.244 ± 0.183(-0.525) vs. 1.091 ± 0.20(-1.342)); FVC (L) (1.402 ± 0.217 (-0.406) vs. 1.265 ± 0.267 (-1.141)), and FVC after betamimetics (1.452 ± 0.237 (-0.241) vs. 1.279 ± 0.264 (-1.020)). PFT showed no differences in the volumes or airway resistance. The global IQ median (interquartile range) was 89 (82:99) vs. 89 (76:98), with 61% of the children >85 in both groups. Repeated surfactant treatment in VPNs presenting severe RDS led to the attenuation of early lung injuries, with an impact on long-term pulmonary sequelae, without differences in neurodevelopmental outcomes.

Patent ductus arteriosus, tracheal ventilation, and the risk of bronchopulmonary dysplasia.

BACKGROUND: An increased risk for bronchopulmonary dysplasia (BPD) exists when moderate-to-large patent ductus arteriosus shunts (hsPDA) persist beyond 14 days. GOAL: To examine the interaction between prolonged exposures to tracheal ventilation (≥10 days) and hsPDA on the incidence of BPD in infants <28 weeks gestation. STUDY DESIGN: Predefined definitions of prolonged ventilation (≥10 days), hsPDA (≥14 days), and BPD (room air challenge test at 36 weeks) were used to analyze deidentified data from the multicenter TRIOCAPI RCT in a secondary analysis of the trial. RESULTS: Among 307 infants who survived >14 days, 41 died before 36 weeks. Among survivors, 93/266 had BPD. The association between BPD and hsPDA depended on the length of intubation. In multivariable analyses, prolonged hsPDA shunts were associated with increased BPD (odds ratio (OR) (95% confidence interval (CI)) = 3.00 (1.58-5.71)) when infants required intubation for ≥10 days. In contrast, there was no significant association between hsPDA exposure and BPD when infants were intubated <10 days (OR (95% CI) = 1.49 (0.98-2.26)). A similar relationship between prolonged hsPDA and length of intubation was found for BPD/death (n = 307): infants intubated ≥10 days: OR (95% CI) = 2.41 (1.47-3.95)); infants intubated <10 days: OR (95% CI) = 1.37 (0.86-2.19)). CONCLUSIONS: Moderate-to-large PDAs were associated with increased risks of BPD and BPD/death-but only when infants required intubation ≥10 days. IMPACT: Infants with a moderate-to-large hsPDA that persist beyond 14 days are only at risk for developing BPD if they also receive prolonged tracheal ventilation for ≥10 days. Infants who receive less ventilatory support (intubation for <10 days) have the same incidence of BPD whether the ductus closes shortly after birth or whether it persists as a moderate-to-large shunt for several weeks. Early PDA closure may be unnecessary in infants who require short durations of intubation since the PDA does not seem to alter the incidence of BPD in infants who require intubation for <10 days.

Effect of Early Targeted Treatment of Ductus Arteriosus with Ibuprofen on Survival Without Cerebral Palsy at 2 Years in Infants with Extreme Prematurity: A Randomized Clinical Trial.

OBJECTIVE: To examine the effects of early echocardiography-targeted ibuprofen treatment of large patent ductus arteriosus (PDA) on survival without cerebral palsy at 24 months of corrected age. STUDY DESIGN: We enrolled infants born at <28 weeks of gestation with a large PDA on echocardiography at 6-12 hours after birth to ibuprofen or placebo by 12 hours of age in a multicenter, double blind, randomized-controlled trial. Open-label ibuprofen was allowed for prespecified criteria of a hemodynamically significant PDA. The primary outcome was survival without cerebral palsy at 24 months of corrected age. RESULTS: Among 337 enrolled infants, 109 had a small or closed ductus and constituted a reference group; 228 had a large PDA and were randomized. The primary outcome was assessed at 2 years in 108 of 114 (94.7%) and 102 of 114 (89.5%) patients allocated to ibuprofen or placebo, respectively. Survival without cerebral palsy occurred in 77 of 108 (71.3%) after ibuprofen, 73 of 102 (71.6%) after placebo (adjusted relative risk 0.98, 95% CI 0.83-1.16, P = .83), and 77 of 101 (76.2%) in reference group. Infants treated with ibuprofen had a lower incidence of PDA at day 3. Severe pulmonary hemorrhage during the first 3 days occurred in 2 of 114 (1.8%) infants treated with ibuprofen and 9 of 114 (7.9%) infants treated with placebo (adjusted relative risk 0.22, 95% CI 0.05-1.00, P = .05). Open-label rescue treatment with ibuprofen occurred in 62.3% of infants treated with placebo and 17.5% of infants treated with ibuprofen (P < .001), at a median (IQR) age of 4 (3, 5) and 4 (4, 12) days, respectively. CONCLUSIONS: Early echocardiography-targeted ibuprofen treatment of a large PDA did not change the rate of survival without cerebral palsy. TRIAL REGISTRATION: Eudract 2011-003063-30 and ClinicalTrials.gov: NCT01630278.

Gestational age-related patterns of AMOT methylation are revealed in preterm infant endothelial progenitors.

OBJECTIVE: Preterm birth is associated with altered angiogenesis and with increased risk of cardiovascular dysfunction and hypertension at adulthood. We previously demonstrated that in preterm newborns circulating cord blood endothelial progenitor cells (ECFC), responsible for angio/vasculogenesis, are reduced in number and display altered angiogenic properties. Altered angiogenic function was associated with a decreased expression of pro-angiogenic genes, among which the AMOT gene which is a strong positive regulator of angiogenesis. Such dysregulation may be related to epigenetic factors. In this study we analyse the methylation profiling of the AMOT gene during development, through a comparative analysis of the cord blood ECFC of preterm newborns and their term counterpart. METHODS: We used both cloning-sequencing and pyrosequencing experiments to perform a comparative analysis of the DNA methylation profile of the promoter CpG island of AMOT gene in the cord blood ECFC of 16 preterm newborns (28-35 weeks gestational age-GA) and 15 term newborns (>37 weeks GA). RESULTS: Twenty nine clones (obtained from 2 term newborns) and forty clones (obtained from 3 preterm newborns) were sequenced. The AMOT gene methylation rate was significantly higher in preterm compared to term newborns (4.5% versus 2.5% respectively: χ2 = 3.84; P = 1.8 10-02). Bisulfite pyrosequencing identified four CpG dinucleotides with significantly higher methylation levels in preterm newborns. This CpG-targeted methylation significantly decreased with increasing gestational age. CONCLUSIONS: These findings highlight importance of pro-angiogenic AMOT gene methylation in ECFC, suggesting that epigenetic mechanisms may control the regulation of angiogenesis during development. Therefore they pave the way to specific short term and long term complications of preterm birth by altered angiogenesis.

Biogenesis of Pro-senescent Microparticles by Endothelial Colony Forming Cells from Premature Neonates is driven by SIRT1-Dependent Epigenetic Regulation of MKK6.

Senescent cells may exert detrimental effect on microenvironment through the secretion of soluble factors and the release of extracellular vesicles, such as microparticles, key actors in ageing and cardiovascular diseases. We previously reported that sirtuin-1 (SIRT1) deficiency drives accelerated senescence and dysfunction of endothelial colony-forming cells (ECFC) in PT neonates. Because preterm birth (PT) increases the risk for cardiovascular diseases during neonatal period as well as at adulthood, we hypothesized that SIRT1 deficiency could control the biogenesis of microparticles as part of a senescence-associated secretory phenotype (SASP) of PT-ECFC and investigated the related molecular mechanisms. Compared to control ECFC, PT-ECFC displayed a SASP associated with increased release of endothelial microparticles (EMP), mediating a paracrine induction of senescence in naïve endothelial cells. SIRT1 level inversely correlated with EMP release and drives PT-ECFC vesiculation. Global transcriptomic analysis revealed changes in stress response pathways, specifically the MAPK pathway. We delineate a new epigenetic mechanism by which SIRT1 deficiency regulates MKK6/p38MAPK/Hsp27 pathway to promote EMP biogenesis in senescent ECFC. These findings deepen our understanding of the role of ECFC senescence in the disruption of endothelial homeostasis and provide potential new targets towards the control of cardiovascular risk in individuals born preterm.

Late Surfactant Administration in Very Preterm Neonates With Prolonged Respiratory Distress and Pulmonary Outcome at 1 Year of Age: A Randomized Clinical Trial.

IMPORTANCE: Although immature neonate survival has improved, there is an increased risk of developing bronchopulmonary dysplasia, leading to significant respiratory morbidity. Measures to reduce bronchopulmonary dysplasia are not always effective or have important adverse effects. OBJECTIVE: To evaluate the effect of late surfactant administration in infants with prolonged respiratory distress on ventilation duration, respiratory outcome at 36 weeks' postmenstrual age, and at 1 year postnatal age. DESIGN, SETTING, AND PARTICIPANTS: Double-blind randomized clinical trial at 13 level III French perinatal centers. Participants included 118 neonates at less than 33 weeks' gestation who still required mechanical ventilation on day 14 (SD, 2) with fraction of inspired oxygen of more than 0.30. All survivors were eligible for follow-up. We performed an intent-to-treat analysis. INTERVENTIONS: Infants received 200 mg/kg of poractant alfa (surfactant) or air after randomization. At 1 year, after parents' interview, infants underwent physical examination by pediatricians not aware of the randomization. MAIN OUTCOMES AND MEASURES: The duration of ventilation was the primary outcome. The combined outcome of death or bronchopulmonary dysplasia at 36 weeks' postmenstrual age and respiratory morbidity at 1 year of age were the main secondary outcome measures. RESULTS: Of the 118 infants who participated in the study, 65 (55%) were male. Fraction of inspired oxygen requirements dropped after surfactant, but not air, for up to 24 hours after instillation (0.36 [0.11] vs 0.43 [0.18]; P < .005). Severe bronchopulmonary dysplasia/death rates at 36 weeks' postmenstrual age were similar (27.1% vs 35.6%; P = .32). Less surfactant-treated infants needed rehospitalization for respiratory problems after discharge (28.3% vs 51.1%; P = .03); 39.5% vs 50% needed respiratory physical therapy (P = .35). No difference was observed for weight (7.8 [1.2] kg vs 7.6 [1.1] kg), height (69 [5] cm vs 69 [3] cm), and head circumference (44.4 [1.7] cm vs 44.2 [1.7] cm) measured at follow-up, nor for neurodevelopment outcome. CONCLUSIONS AND RELEVANCE: Late surfactant administration did not alter the early course of bronchopulmonary dysplasia. However, surfactant-treated infants had reduced respiratory morbidity prior to 1 year of age. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01039285.

Accelerated senescence of cord blood endothelial progenitor cells in premature neonates is driven by SIRT1 decreased expression.

Epidemiological and experimental studies indicate that early vascular dysfunction occurs in low-birth-weight subjects, especially preterm (PT) infants. We recently reported impaired angiogenic activity of endothelial colony-forming cells (ECFCs) in this condition. We hypothesized that ECFC dysfunction in PT might result from premature senescence and investigated the underlying mechanisms. Compared with ECFCs from term neonates (n = 18), ECFCs isolated from PT (n = 29) display an accelerated senescence sustained by growth arrest and increased senescence-associated ß-galactosidase activity. Increased p16(INK4a) expression, in the absence of telomere shortening, indicates that premature PT-ECFC aging results from stress-induced senescence. SIRT1 level, a nicotinamide adenine dinucleotide-dependent deacetylase with anti-aging activities, is dramatically decreased in PT-ECFCs and correlated with gestational age. SIRT1 deficiency is subsequent to epigenetic silencing of its promoter. Transient SIRT1 overexpression or chemical induction by resveratrol treatment reverses senescence phenotype, and rescues in vitro PT-ECFC angiogenic defect in a SIRT1-dependent manner. SIRT1 overexpression also restores PT-ECFC capacity for neovessel formation in vivo. We thus demonstrate that decreased expression of SIRT1 drives accelerated senescence of PT-ECFCs, and acts as a critical determinant of the PT-ECFC angiogenic defect. These findings lay new grounds for understanding the increased cardiovascular risk in individuals born prematurely and open perspectives for therapeutic strategy.

Altered angiogenesis in low birth weight individuals: a role for anti-angiogenic circulating factors.

OBJECTIVE: Low birth weight (LBW) is a risk factor for hypertension at adulthood. Endothelial progenitor cells (EPCs) dysfunction has been characterized in LBW neonates. We hypothesized that changes in soluble, plasma pro- or anti-angiogenic factors are associated with EPCs dysfunction and impaired angiogenesis in LBW neonates. METHOD: Venous umbilical cord blood was collected from 42 normal, term neonates and 75 LBW neonates. Cord blood endothelial colony forming cells (ECFC) from control patients were cultured in the presence of 10% of serum obtained from both groups. RESULTS: The proliferation and the migration of ECFC were significantly reduced when cultured with 10% of serum of LBW neonates compared to serum of control neonates. Matrigel invasion assay was not significantly altered. Umbilical vein plasma VEGF concentration was significantly reduced in LBW neonates while that of sVEGFR and PF4 were significantly higher. Addition of VEGF corrected the inhibitory effect of LBW serum on normal ECFC proliferation. CONCLUSIONS: Serum obtained from LBW babies contains factors that exhibit an antiangiogenic effect on ECFC proliferation and migration. VEGF/sVEGF/PF4 pathway seems to be involved in the EPCs dysfunction in LBW neonates.

Ibubrofen in the treatment of patent ductus arteriosus in preterm infants: what we know, what we still do not know.

The patency of the ductus arteriosus has ever been considered as a pathological situation in preterm infants and one likely cause of mortality and morbidity, including broncho-pulmonary dysplasia, necrotizing enterocolitis, intraventricular haemorrhage, retinopathy of prematurity. The incidence of patent ductus arteriosus is inversely proportional to gestational age and infants with the lowest gestational ages are the most exposed to the complications of prematurity. So, associations between patent ductus arteriosus and the other morbidities may not be causative and patent ductus arteriosus could be more a sign of immaturity and severity of disease than the cause of these problems. Non-steroidal anti-inflammatory agents, such as indomethacin or ibuprofen, have been shown to be effective in closing or preventing patent ductus arteriosus, with differences in side effects. However nearly all randomized controlled trials have been designed with the closure of the ductus arteriosus, not mortality or morbidity, as the main endpoint. Thus, evidence is still lacking on the eventual benefits for the patient of pharmacological or surgical intervention on PDA. Moreover, both ibuprofen and indomethacin efficacy seems markedly reduced in extremely low gestational age infants, who are the most likely to benefit from such intervention. The explanation of the reduced pharmacodymanic effect in such population is unclear; so far, studies using increased dosing of ibuprofen have failed to show a clear benefit. Prophylaxis with indomethacin or ibuprofen has failed to show sustained benefits on neurodevelopment at 2 years of age in low gestational age infants. New curative trials may aim at investigating the effects of early curative administration of ibuprofen, which has reduced side effects compared to indomethacin, on immature kidney function, on mortality and morbidity in very low gestational age infants, ideally with a combined endpoint such as survival in the absence of severe neurodevelopmental alteration at 2 years age. Despite an understandable reluctance given the historical background of systematic, therapeutic closure of ductus arteriosus in preterm infants, there are no definite ethical obstacles to a placebo-controlled design.

The intensity of IUGR-induced transcriptome deregulations is inversely correlated with the onset of organ function in a rat model.

A low-protein diet applied during pregnancy in the rat results in intrauterine growth restricted (IUGR) fetuses. In humans, IUGR is associated with increased perinatal morbidity, higher incidence of neuro-developmental defects and increased risk of adult metabolic anomalies, such as diabetes and cardiovascular disease. Development and function of many organs are affected by environmental conditions such as those inducing fetal and early postnatal growth restriction. This phenomenon, termed "fetal programming" has been studied unconnectedly in some organs, but very few studies (if any) have investigated at the same time several organs, on a more comparative basis. However, it is quite probable that IUGR affects differentially most organ systems, with possible persistent changes in gene expression. In this study we address transcriptional alterations induced by IUGR in a multi-organ perspective, by systematic analysis of 20-days rat fetuses. We show that (1) expressional alterations are apparently stronger in organs functioning late in foetal or postnatal life than in organs that are functioning early (2) hierarchical classification of the deregulations put together kidney and placenta in one cluster, liver, lungs and heart in another; (3) the epigenetic machinery is set up especially in the placenta, while its alterations are rather mild in other organs; (4) the genes appear deregulated in chromosome clusters; (5) the altered expression cascades varies from organ to organ, with noticeably a very significant modification of the complement and coagulation cascades in the kidney; (6) we found a significant increase in TF binding site for HNF4 proteins specifically for liver genes that are down-regulated in IUGR, suggesting that this decrease is achieved through the action of HNF transcription factors, that are themselves transcriptionnally induced in the liver by IUGR (x 1.84 fold). Altogether, our study suggests that a combination of tissue-specific mechanisms contributes to bring about tissue-driven modifications of gene cascades. The question of these cascades being activated to adapt the organ to harsh environmental condition, or as an endpoint consequence is still raised.

A switch toward angiostatic gene expression impairs the angiogenic properties of endothelial progenitor cells in low birth weight preterm infants.

Low birth weight (LBW) is associated with increased risk of cardiovascular diseases at adulthood. Nevertheless, the impact of LBW on the endothelium is not clearly established. We investigate whether LBW alters the angiogenic properties of cord blood endothelial colony forming cells (LBW-ECFCs) in 25 preterm neonates compared with 25 term neonates (CT-ECFCs). We observed that LBW decreased the number of colonies formed by ECFCs and delayed the time of appearance of their clonal progeny. LBW dramatically reduced LBW-ECFC capacity to form sprouts and tubes, to migrate and to proliferate in vitro. The angiogenic defect of LBW-ECFCs was confirmed in vivo by their inability to form robust capillary networks in Matrigel plugs injected in nu/nu mice. Gene profile analysis of LBW-ECFCs demonstrated an increased expression of antiangiogenic genes. Among them, thrombospondin 1 (THBS1) was highly expressed at RNA and protein levels in LBW-ECFCs. Silencing THBS1 restored the angiogenic properties of LBW-ECFCs by increasing AKT phosphorylation. The imbalance toward an angiostatic state provide a mechanistic link between LBW and the impaired angiogenic properties of ECFCs and allows the identification of THBS1 as a novel player in LBW-ECFC defect, opening new perspectives for novel deprogramming agents.

Clinical research in newborn infants: difficulties and specificity.

BACKGROUND: Clinical trials are essential in neonates to evaluate scientifically the efficacy and safety of drugs. However, major specificities condition clinical research in human neonates. OBJECTIVE: To review specific constraints to be taken into account in neonatal research studies. METHODS: A review of the literature and contribution of authors' opinions was carried out. RESULTS AND CONCLUSION: Neonatal specificities that induce obstacles in neonatal studies and proposals are detailed. This review also looks at recommendations recently developed by the European Commission to promote safe and ethical research in neonatology.

Adverse consequences of accelerated neonatal growth: cardiovascular and renal issues.

Epidemiological and experimental studies show that the risk of cardiovascular and metabolic diseases at adulthood is inversely related to the weight at birth. Although with less evidence, low birth weight has been suggested to increase the risk of chronic kidney disease (CKD). It is well established that the developmental programming of arterial hypertension and of renal disease involves in particular renal factors, especially nephron endowment, which is reduced in low birth weight and maternal diabetes situations. Experimental studies, especially in rodents, have demonstrated the long-term influence of postnatal nutrition and/or postnatal growth on cardiovascular, metabolic and renal functions, while human data are scarce on this issue. Vascular and renal diseases appear to have a "multihits" origin, with reduced nephron number the initial hit and rapid postnatal growth the second hit. This review addresses the current understanding of the role of the kidney, both as a mechanism and as a target, in the developmental origins of adult disease theory, with a particular focus on the long-term effects of postnatal growth and nutrition.

[Early origins of arterial hypertension and cardiovascular diseases]. / Les origines précoces de l'hypertension artérielle et des maladies cardio-vasculaires.

Research has shown that most of the principal causes of mortality in industrialized countries have their roots in early development. Thus, the period from conception through pregnancy to early infancy is uniquely sensitive to long-lasting effects of environmental insults, potentially leading to physiological malprogramming and lifelong disease. Beyond the classical association between low birth weight and increased coronary mortality in adulthood, peri-conceptional and perinatal insults can set the scene for later obesity, cancer and behavioral disorders. Taking the developmental programming of hypertension as an example, this review addresses the remarkably similar mechanisms of early programming, particularly those involving the kidney and vasculature ; the continuum between normality and disease ; the role of early and later nutrition ; and early biomarkers and epigenetic mechanisms of later cardiovascular and metabolic disorders. The developmental origins of adult health and disease represent a global research challenge as emerging countries undergo major nutritional and environmental upheavals. Much research is focused on the benefits of early nutritional and lifestyle interventions, in both animal models and human studies.

Iatrogenic events in neonates: beneficial effects of prevention strategies and continuous monitoring.

OBJECTIVES: To assess the impact of continuous incident reporting and subsequent prevention strategies on the incidence of severe iatrogenic events and targeted priorities in admitted neonates. METHODS: We performed preintervention (January 1 to September 1, 2005) and postintervention (January 1, 2008, to January 1, 2009) prospective investigations based on continuous incident reporting. Patient-safety initiatives were implemented for a period of 2 years. The main outcome was a reduction in the incidence of severe iatrogenic events. Secondary outcomes were improvements in 5 targeted priorities: catheter-related infections; invasive procedures; unplanned extubations; 10-fold drug infusion-rate errors; and severe cutaneous injuries. RESULTS: The first and second study periods included totals of 388 and 645 patients (median gestational ages: 34 and 35 weeks, respectively; P = .015). In the second period the incidence of severe iatrogenic events was significantly reduced from 7.6 to 4.8 per 1000 patient-days (P = .005). Infections related to central catheters decreased significantly from 13.9 to 8.2 per 1000 catheter-days (P < .0001), as did exposure to central catheters, which decreased from 359 to 239 days per 1000 patient-days (P < .0001). Tenfold drug-dosing errors were reduced significantly (P = .022). However, the number of unplanned extubations increased significantly from 5.6 to 15.5 per 1000 ventilation-days (P = .03). CONCLUSIONS: Prospective, continuous incident reporting followed by the implementation of prevention strategies are complementary procedures that constitute an effective system to improve the quality of care and patient safety.

Low birth weight infants and the developmental programming of hypertension: a focus on vascular factors.

Low birth weight infants, in particular those born preterm, have been shown to develop increased arterial blood pressure and hypertension at adulthood. Three main systems are involved in the developmental programming of hypertension: the kidney, the neuroendocrine system, and the vascular tree. This review focuses on vascular dysfunction and discusses clinical and experimental evidence that relates low birth weight and the risk for hypertension at adulthood. Recent studies demonstrate an impairment of vascular structure and function. Both arterial vessels, through altered arterial stiffness and endothelium-dependent vasodilation, and the capillary bed, through microvascular rarefaction, are involved in the early pathogenesis of hypertension. The key role of the endothelium, as shown by altered vasodilatation, angiogenesis, endothelial progenitor cells, and microparticle number and function, is discussed as a possible explanatory mechanism.

Iatrogenic events in admitted neonates: a prospective cohort study.

BACKGROUND: Iatrogenic events are increasingly recognised as an important problem in all people admitted to hospital. However, few epidemiological data are available for iatrogenic events in neonatal high-risk units. We aimed to assess the incidence, nature, preventability, and severity of iatrogenic events in a neonatal centre and to establish the association of patient characteristics with the occurrence of iatrogenic events in neonates. METHODS: We undertook an observational, prospective study from Jan 1, 2005, to Sept 1, 2005, including all neonates admitted in the Division of Neonatology of an academic, tertiary neonatal centre in southern France. Iatrogenic events were defined as any event that compromised the safety margin for the patient, in the presence or absence of harm. The report of an iatrogenic event was voluntary, anonymous, and non-punitive. The primary outcome was the rate of iatrogenic events per 1000 patient days. FINDINGS: A total of 388 patients were studied during 10 436 patient days. We recorded 267 iatrogenic events in 116 patients. The incidence of iatrogenic events was 25.6 per 1000 patient days. 92 (34%) were preventable and 78 (29%) were severe. Two iatrogenic events (1%) were fatal, but neither was preventable. The most severe iatrogenic events were nosocomial infections (49/62 [79%]) and respiratory events (nine of 26 [35%]). Cutaneous injuries were frequent (n=94) but generally minor (89 [95%]), as were medication errors (15/19 [76%]). Most medication errors occurred during administration stage (12/19 [63%]) and were ten-fold errors (nine of 19 [47%]). The major risk factors were low birthweight and gestational age (both p<0.0001), length of stay (p<0.0001), a central venous line (p<0.0001), mechanical ventilation (p=0.0021), and support with continuous positive airwary pressure (p=0.0076). INTERPRETATION: Iatrogenic events occur frequently and are often serious in neonates, especially in infants of low birthweight. Improved knowledge of the incidence and characteristics of iatrogenic events, and continuous monitoring could help to improve quality of health care for this vulnerable population.