Objective:To compare the short-term outcomes of very low birth weight (VLBW) and extremely low birth weight (ELBW) infants supplementarily fed with fortified donor human milk (DHM) or preterm formula (PF) when the mother's own milk (MOM) is insufficient.Methods:This retrospective cohort study included 91 VLBW or ELBW preterm infants with birth weight<1 500 g who were hospitalized in Peking Union Medical College Hospital from October 1, 2017, to September 30, 2020. Based on the supplemental feeding method when MOM was insufficient, these infants were divided into the DHM group ( n=51) and PF group ( n=40). Mann-Whitney U, t-test, Chi-square test, or Fisher's exact test were used to compare the short-term clinical outcomes during hospitalization between the two groups. Results:(1) There were no statistically significant differences between the 91 preterm infants in the DHM group and PF group in their gestational age, birth weight, sex ratio, birth mode, mothers' age at delivery, or the proportion of infants of small gestational age (all P>0.05). (2) The feeding volume in the DHM group was significantly greater than that in the PF group on the 14th day after birth [(108.2±53.1) vs. (81.0±47.8) ml/(kg·d), t=0.78, P=0.020]. Moreover, the time to achieve the feeding amounts up to 120 ml/(kg·d) and 150 ml/(kg·d) for infants in the DHM group were significantly shorter than those in the PF group [(17.5±10.2) vs. (30.0±12.0) d, t=4.38; (22.1±13.3) vs. (32.3±11.9) d, t=0.02; both P<0.05]; (3) Lower proportion of peripherally inserted central catheter (PICC) [58.8% (30/51) vs. 100% (40/40), χ 2=21.88, P<0.001] and shorter PICC duration were observed in the DHM group [10.0 (0.0-19.0) vs. 29.0 (17.0-40.5) d, Z=5.56, P<0.001] compared to the PF group. The times of red blood cell transfusions and the incidence of late sepsis in the DHM group were less than those in the PF group [0.0 (0.0-2.0) vs. 2.0 (1.0-3.0) times, Z=4.44, P<0.001; 23.5% (12/51) vs. 50.0% (20/40), χ 2=6.39, P=0.011]. There were no statistically significant differences observed in the incidence of bronchopulmonary dysplasia, neonatal necrotizing enterocolitis, retinopathy of prematurity, and the length of hospitalization (all P>0.05). Conclusion:When MOM is insufficient, supplementing VLBW and ELBW infants with fortified donor human milk can shorten the time to achieve enteral nutrition and reduce the use rate and time of PICC, the incidence of late-onset sepsis, and the times of red blood cell transfusion.

Patients with severe trauma require an extremely timely treatment and transfusion plays an irreplaceable role in the emergency treatment of such patients. An increasing number of evidence-based medicinal evidences and clinical practices suggest that patients with severe traumatic bleeding benefit from early transfusion of low-titer group O whole blood or hemostatic resuscitation with red blood cells, plasma and platelet of a balanced ratio. However, the current domestic mode of blood supply cannot fully meet the requirements of timely and effective blood transfusion for emergency treatment of patients with severe trauma in clinical practice. In order to solve the key problems in blood supply and blood transfusion strategies for emergency treatment of severe trauma, Branch of Clinical Transfusion Medicine of Chinese Medical Association, Group for Trauma Emergency Care and Multiple Injuries of Trauma Branch of Chinese Medical Association, Young Scholar Group of Disaster Medicine Branch of Chinese Medical Association organized domestic experts of blood transfusion medicine and trauma treatment to jointly formulate Chinese expert consensus on blood support mode and blood transfusion strategies for emergency treatment of severe trauma patients ( version 2024). Based on the evidence-based medical evidence and Delphi method of expert consultation and voting, 10 recommendations were put forward from two aspects of blood support mode and transfusion strategies, aiming to provide a reference for transfusion resuscitation in the emergency treatment of severe trauma and further improve the success rate of treatment of patients with severe trauma.

Objective:To investigate the effect of selenium on cyclophosphamide(CTX)-induced spermatogenic impairment(SI)in mice and its underlying mechanism.Methods:We equally randomized 36 male KM mice into 3 SI model and 3 control groups,the first 3 treated by intraperitoneal injection of CTX at 100 mg/kg(the SI model control group),CTX plus SI model control group,selenium deficient model group(-Se SI),selenium supplemented model group(+Se SI),while latter 3 by intraperitoneal injection of normal saline(the normal control),selenium deficiency control group(-Se control),selenium addition control group(+Se control),respectively,all once a week for 6 successive weeks.Then we observed the histopathological changes in the testes of all the mice by HE staining,obtained the sperm count in the epididymides,determined the expressions of glutathione peroxidase 4(GPx4)and SLC7A11 proteins by Western blot and ferroptosis-related genes by RT-qPCR,and examined the changes in the expres-sions of ferroptosis-related proteins and genes in the GC2-spd cells treated with ferroptosis inhibitors and inducers in combination with different concentrations of inorganic sodium selenite(SeS)and organic selenomethionine(SeM).Results:Compared with the nor-mal controls,the SI model mice showed significantly decreased testicular and prostatic organ coefficients,reduced spermatogenic lay-ers,increased voids,decreased serum ferritin concentration(P<0.05),and elevated transferrin concentration(P<0.05).The or-gan coefficients were significantly higher in the+Se SI and+Se control than in the-Se SI and-Se control groups(P<0.05,P<0.01),with evident pathological improvement of the testis tissue in the+Se controls.The expressions of the GPx4 and solute carrier family 7 members 11(SLC7A11)genes in the testis were dramatically down-regulated in the SI model controls(P<0.01),but up-reg-ulated in the+Se SI and+Se control compared with those in the-Se SI and-Se control group(P<0.01 and P<0.05),but there were no statistically significant differences between their protein expressions.The results of in vitro GC2 spd cell experiments indicated that the GPx4 gene and GPx4 protein levels in the-Se group were significantly lower than those in the normal control group(P<0.05),while the SLC7A11 gene level decreased(P<0.01).Different doses of SeS and SeM significantly increased the GPx4 protein expression compared to the average Se group.Low doses of SeM promoted a significant increase in GPx4 gene levels,while high doses of SeS increased the expression levels of SLC7A11 gene and SLC7A11 protein(P<0.05,P<0.01).The Se group showed a signifi-cant decrease in the levels of acsl4 and ptgs2 genes compared to the normal control group.SeM promoted the expression of acsl4,while SeS promoted the expression of ptgs2 and fth1(P<0.01,P<0.05).The intervention results of GC2 spd showed that the Erastin group had a decrease in ptgs2 compared to the normal control group,while the SeS+Erastin and SeM+Erastin groups had an increase in ptgs2 gene expression compared to the Erastin group.However,the ptgs2 expression of Fer-1 was lower than that of the normal con-trol group,and the ptgs2 gene level of SeS+Fer-1 and SeM+Fer-1 groups was lower than that of Fer-1 group(P<0.05);The gene quantity of GPx4 in the SeM+Erastin and SeM+Fer-1 groups increased compared to the Erastin and Fer-1 groups(P<0.01,P<0.05);SeM+Erastin and SeS+Erastin showed a decrease in SLC7A11 compared to the Erastin group,as well as SeM+Fer-1 and SeS+Fer-1 groups compared to the Fer-1 group,accompanied by an increase in acsl4 and fth1(P<0.01).Conclusion:Selenium deficiency causes the reduction of the SLC7A11 and GPx4 gene levels,disorder of ferroptosis-related genes and down-regulation of the GPx4 protein expression in the mouse testis and spermatocytes.Selenium can promote the expression of GPx4,up-regulate the level of SLC7A11,and improve spermatogenesis in the testis of the mouse with SI.There are differences between organic SeM and inorganic SeS in regulating the ferroptosis pathway-related genes.

Objective To investigate the clinical characteristics and prognosis of pneumococcal meningitis(PM),and drug sensitivity of Streptococcus pneumoniae(SP)isolates in Chinese children.Methods A retrospective analysis was conducted on clinical information,laboratory data,and microbiological data of 160 hospitalized children under 15 years old with PM from January 2019 to December 2020 in 33 tertiary hospitals across the country.Results Among the 160 children with PM,there were 103 males and 57 females.The age ranged from 15 days to 15 years,with 109 cases(68.1% )aged 3 months to under 3 years.SP strains were isolated from 95 cases(59.4% )in cerebrospinal fluid cultures and from 57 cases(35.6% )in blood cultures.The positive rates of SP detection by cerebrospinal fluid metagenomic next-generation sequencing and cerebrospinal fluid SP antigen testing were 40% (35/87)and 27% (21/78),respectively.Fifty-five cases(34.4% )had one or more risk factors for purulent meningitis,113 cases(70.6% )had one or more extra-cranial infectious foci,and 18 cases(11.3% )had underlying diseases.The most common clinical symptoms were fever(147 cases,91.9% ),followed by lethargy(98 cases,61.3% )and vomiting(61 cases,38.1% ).Sixty-nine cases(43.1% )experienced intracranial complications during hospitalization,with subdural effusion and/or empyema being the most common complication[43 cases(26.9% )],followed by hydrocephalus in 24 cases(15.0% ),brain abscess in 23 cases(14.4% ),and cerebral hemorrhage in 8 cases(5.0% ).Subdural effusion and/or empyema and hydrocephalus mainly occurred in children under 1 year old,with rates of 91% (39/43)and 83% (20/24),respectively.SP strains exhibited complete sensitivity to vancomycin(100% ,75/75),linezolid(100% ,56/56),and meropenem(100% ,6/6).High sensitivity rates were also observed for levofloxacin(81% ,22/27),moxifloxacin(82% ,14/17),rifampicin(96% ,25/26),and chloramphenicol(91% ,21/23).However,low sensitivity rates were found for penicillin(16% ,11/68)and clindamycin(6% ,1/17),and SP strains were completely resistant to erythromycin(100% ,31/31).The rates of discharge with cure and improvement were 22.5% (36/160)and 66.2% (106/160),respectively,while 18 cases(11.3% )had adverse outcomes.Conclusions Pediatric PM is more common in children aged 3 months to under 3 years.Intracranial complications are more frequently observed in children under 1 year old.Fever is the most common clinical manifestation of PM,and subdural effusion/emphysema and hydrocephalus are the most frequent complications.Non-culture detection methods for cerebrospinal fluid can improve pathogen detection rates.Adverse outcomes can be noted in more than 10% of PM cases.SP strains are high sensitivity to vancomycin,linezolid,meropenem,levofloxacin,moxifloxacin,rifampicin,and chloramphenicol.[Chinese Journal of Contemporary Pediatrics,2024,26(2):131-138]

Objective To explore the molecular epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae(CRKP),and reveal its mechanism of resistance to ceftazidime/avibactam(CZA).Methods CZA-re-sistant CRKP strains initially isolated from the Affiliated Hospital of Xuzhou Medical University from January 2021 to September 2023 were collected.The carriage of 5 carbapenemase genes(blaKPC,blaNDM,blaOXA,blaVIM,blaIMp)were detected with gene amplification method and colloidal gold method.The relative copy number and expression level of Klebsiella pneumoniae(KP)carbapenemase-producing KP(KPC-KP)was detected with real-time quantita-tive polymerase chain reaction(RT-qPCR),mutation sites of KPC mutation strains were analyzed with whole-ge-nome sequencing,and epidemic characteristics of CRKP and resistance mechanism to CZA were analyzed.Results A total of 73 CZA-resistant CRKP strains were isolated,with 37(50.68％)being KPC and NDM co-producing strains,33(45.21％)NDM-producing alone(23 strains producing NDM-5 and 10 strains producing NDM-1),and 3 KPC-producing alone.KP-2842 strain was identified as ST11-type KPC-33 variant,KP-2127 and KP-2189 strains produced KPC-2.Compared with KP ATCC BAA-1705,the copy number of blaKPC in these strains up-regulated by 1.04-3.86 fold,and the expression increased by 6.66-12.93 fold,respectively.Colloidal gold and PCR methods demonstrated good consistency and the ability to detect the enzyme co-producing and KPC-33 variant.Conclusion In this hospital,the resistance of CRKP to CZA is primarily mediated by the metalloenzyme NDM,with co-produc-tion of NDM and KPC being a characteristic of CRKP.High copy number and expression level of blaKPC-2 also con-tribute to CZA resistance.This study identified the KPC-33 variant for the first time in ST11-type CRKP in Jiangsu Province.

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death among urban and rural residents in China, and elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for ASCVD. Considering the increasing burden of ASCVD, lipid management is of the utmost importance. In recent years, research on blood lipids has made breakthroughs around the world, hence a revision of China guidelines for lipid management is imperative, especially since the target lipid levels in the general population vary in respect to the risk of ASCVD. The level of LDL-C, which can be regarded as appropriate in a population without frisk factors, can be considered abnormal in people at high risk of developing ASCVD. As a result, the "Guidelines for the prevention and treatment of dyslipidemia" were adapted into the "China Guidelines for Lipid Management" (henceforth referred to as the new guidelines) by an Experts' committee after careful deliberation. The new guidelines still recommend LDL-C as the primary target for lipid control, with CVD risk stratification to determine its target value. These guidelines recommend that moderate intensity statin therapy in adjunct with a heart-healthy lifestyle, be used as an initial line of treatment, followed by cholesterol absorption inhibitors or/and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as necessary. The new guidelines provide guidance for lipid management across various age groups, from children to the elderly. The aim of these guidelines is to comprehensively improve the management of lipids and promote the prevention and treatment of ASCVD by guiding clinical practice.

Objective: To investigate the clinical presentation and genetic characteristics of malignant infantile osteopetrosis. Methods: This was a retrospective case study. Thirty-seven children with malignant infantile osteopetrosis admitted into Beijing Children's Hospital from January 2013 to September 2022 were enrolled in this study. According to the gene mutations, the patients were divided into the CLCN7 group and the TCIRG1 group. Clinical characteristics, laboratory tests, and prognosis were compared between two groups. Wilcoxon test or Fisher exact test were used in inter-group comparison. The survival rate was estimated with the Kaplan-Meier method and the Log-Rank test was used to compare the difference in survival between groups. Results: Among the 37 cases, there were 22 males and 15 females. The age of diagnosis was 0.5 (0.2, 1.0) year. There were 13 patients (35%) and 24 patients (65%) with mutations in CLCN7 and TCIRGI gene respectively. Patients in the CLCN7 group had an older age of diagnosis than those in the TCIRGI group (1.2 (0.4, 3.6) vs. 0.4 (0.2, 0.6) years, Z=-2.60, P=0.008). The levels of serum phosphorus (1.7 (1.3, 1.8) vs. 1.1 (0.8, 1.6) mmol/L, Z=-2.59, P=0.010), creatine kinase isoenzyme (CK-MB) (457 (143, 610) vs. 56 (37, 82) U/L, Z=-3.38, P=0.001) and the level of neutrophils (14.0 (9.9, 18.1) vs. 9.2 (6.7, 11.1) ×10⁹/L, Z=-2.07, P=0.039) at diagnosis were higher in the CLCN7 group than that in the TCIRG1 group. However, the level of D-dimer in the CLCN7 group was lower than that in the TCIRGI group (2.7 (1.0, 3.1) vs. 6.3 (2.5, 9.7) μg/L, Z=2.83, P=0.005). After hematopoietic stem cell transplantation, there was no significant difference in 5-year overall survival rate between the two groups (92.3%±7.4% vs. 83.3%±7.6%, χ²=0.56, P=0.456). Conclusions: TCIRGI gene mutations are more common in children with osteopetrosis. Children with TCIRGI gene mutations have younger age, lower levels of phosphorus, CK-MB, and neutrophils and higher level of D-dimer at the onset. After hematopoietic stem cell transplantation, patients with CLCN7 or TCIRGI gene mutations have similar prognosis.
Child ; Male ; Female ; Humans ; Osteopetrosis/therapy* ; Retrospective Studies ; Prognosis ; Genes, Recessive ; Phosphorus ; Chloride Channels/genetics* ; Vacuolar Proton-Translocating ATPases/genetics*

Objective:To investigate the diagnostic accuracy of serological indicators and evaluate the diagnostic value of a new established combined serological model on identifying the minimal hepatic encephalopathy (MHE) in patients with compensated cirrhosis.Methods:This prospective multicenter study enrolled 263 compensated cirrhotic patients from 23 hospitals in 15 provinces, autonomous regions and municipalities of China between October 2021 and August 2022. Clinical data and laboratory test results were collected, and the model for end-stage liver disease (MELD) score was calculated. Ammonia level was corrected to the upper limit of normal (AMM-ULN) by the baseline blood ammonia measurements/upper limit of the normal reference value. MHE was diagnosed by combined abnormal number connection test-A and abnormal digit symbol test as suggested by Guidelines on the management of hepatic encephalopathy in cirrhosis. The patients were randomly divided (7∶3) into training set ( n=185) and validation set ( n=78) based on caret package of R language. Logistic regression was used to establish a combined model of MHE diagnosis. The diagnostic performance was evaluated by the area under the curve (AUC) of receiver operating characteristic curve, Hosmer-Lemeshow test and calibration curve. The internal verification was carried out by the Bootstrap method ( n=200). AUC comparisons were achieved using the Delong test. Results:In the training set, prevalence of MHE was 37.8% (70/185). There were statistically significant differences in AMM-ULN, albumin, platelet, alkaline phosphatase, international normalized ratio, MELD score and education between non-MHE group and MHE group (all P<0.05). Multivariate Logistic regression analysis showed that AMM-ULN [odds ratio ( OR)=1.78, 95% confidence interval ( CI) 1.05-3.14, P=0.038] and MELD score ( OR=1.11, 95% CI 1.04-1.20, P=0.002) were independent risk factors for MHE, and the AUC for predicting MHE were 0.663, 0.625, respectively. Compared with the use of blood AMM-ULN and MELD score alone, the AUC of the combined model of AMM-ULN, MELD score and education exhibited better predictive performance in determining the presence of MHE was 0.755, the specificity and sensitivity was 85.2% and 55.7%, respectively. Hosmer-Lemeshow test and calibration curve showed that the model had good calibration ( P=0.733). The AUC for internal validation of the combined model for diagnosing MHE was 0.752. In the validation set, the AUC of the combined model for diagnosing MHE was 0.794, and Hosmer-Lemeshow test showed good calibration ( P=0.841). Conclusion:Use of the combined model including AMM-ULN, MELD score and education could improve the predictive efficiency of MHE among patients with compensated cirrhosis.

Objective: To evaluate the efficacy and safety of Nocardia rubra cell wall skeleton (Nr-CWS) in the treatment of persistent cervical high-risk human papillomavirus (HR-HPV) infection. Methods: A randomized, double blind, multi-center trial was conducted. A total of 688 patients with clinically and pathologically confirmed HR-HPV infection of the cervix diagnosed in 13 hispital nationwide were recruited and divided into: (1) patients with simple HR-HPV infection lasting for 12 months or more; (2) patients with cervical intraepithelial neoplasia (CIN) Ⅰ and HR-HPV infection lasting for 12 months or more; (3) patients with the same HR-HPV subtype with no CINⅡ and more lesions after treatment with CINⅡ or CIN Ⅲ (CINⅡ/CIN Ⅲ). All participants were randomly divided into the test group and the control group at a ratio of 2∶1. The test group was locally treated with Nr-CWS freeze-dried powder and the control group was treated with freeze-dried powder without Nr-CWS. The efficacy and negative conversion rate of various subtypes of HR-HPV were evaluated at 1, 4, 8, and 12 months after treatment. The safety indicators of initial diagnosis and treatment were observed. Results: (1) This study included 555 patients with HR-HPV infection in the cervix (included 368 in the test group and 187 in the control group), with an age of (44.1±10.0) years. The baseline characteristics of the two groups of subjects, including age, proportion of Han people, weight, composition of HR-HPV subtypes, and proportion of each subgroup, were compared with no statistically significant differences (all P>0.05). (2) After 12 months of treatment, the effective rates of the test group and the control group were 91.0% (335/368) and 44.9% (84/187), respectively. The difference between the two groups was statistically significant (χ²=142.520, P<0.001). After 12 months of treatment, the negative conversion rates of HPV 16, 18, 52, and 58 infection in the test group were 79.2% (84/106), 73.3% (22/30), 83.1% (54/65), and 77.4% (48/62), respectively. The control group were 21.6% (11/51), 1/9, 35.1% (13/37), and 20.0% (8/40), respectively. The differences between the two groups were statistically significant (all P<0.001). (3) There were no statistically significant differences in vital signs (body weight, body temperature, respiration, pulse rate, systolic blood pressure, diastolic blood pressure, etc.) and laboratory routine indicators (blood cell analysis, urine routine examination) between the test group and the control group before treatment and at 1, 4, 8, and 12 months after treatment (all P>0.05); there was no statistically significant difference in the incidence of adverse reactions related to the investigational drug between the two groups of subjects [8.7% (32/368) vs 8.0% (15/187), respectively; χ²=0.073, P=0.787]. Conclusion: External use of Nr-CWS has good efficacy and safety in the treatment of high-risk HPV persistent infection in the cervix.
Female ; Humans ; Adult ; Middle Aged ; Cervix Uteri/pathology* ; Uterine Cervical Neoplasms/pathology* ; Papillomavirus Infections/diagnosis* ; Cell Wall Skeleton ; Persistent Infection ; Powders ; Uterine Cervical Dysplasia/pathology* ; Immunotherapy ; Papillomaviridae

Objective: To analyze the prevalence and the risk factors of fungal sepsis in 25 neonatal intensive care units (NICU) among preterm infants in China, and to provide a basis for preventive strategies of fungal sepsis. Methods: This was a second-analysis of the data from the "reduction of infection in neonatal intensive care units using the evidence-based practice for improving quality" study. The current status of fungal sepsis of the 24 731 preterm infants with the gestational age of <34⁺⁰ weeks, who were admitted to 25 participating NICU within 7 days of birth between May 2015 and April 2018 were retrospectively analyzed. These preterm infants were divided into the fungal sepsis group and the without fungal sepsis group according to whether they developed fungal sepsis to analyze the incidences and the microbiology of fungal sepsis. Chi-square test was used to compare the incidences of fungal sepsis in preterm infants with different gestational ages and birth weights and in different NICU. Multivariate Logistic regression analysis was used to study the outcomes of preterm infants with fungal sepsis, which were further compared with those of preterm infants without fungal sepsis. The 144 preterm infants in the fungal sepsis group were matched with 288 preterm infants in the non-fungal sepsis group by propensity score-matched method. Univariate and multivariate Logistic regression analysis were used to analyze the risk factors of fungal sepsis. Results: In all, 166 (0.7%) of the 24 731 preterm infants developed fungal sepsis, with the gestational age of (29.7±2.0) weeks and the birth weight of (1 300±293) g. The incidence of fungal sepsis increased with decreasing gestational age and birth weight (both P<0.001). The preterm infants with gestational age of <32 weeks accounted for 87.3% (145/166). The incidence of fungal sepsis was 1.0% (117/11 438) in very preterm infants and 2.0% (28/1 401) in extremely preterm infants, and was 1.3% (103/8 060) in very low birth weight infants and 1.7% (21/1 211) in extremely low birth weight infants, respectively. There was no fungal sepsis in 3 NICU, and the incidences in the other 22 NICU ranged from 0.7% (10/1 397) to 2.9% (21/724), with significant statistical difference (P<0.001). The pathogens were mainly Candida (150/166, 90.4%), including 59 cases of Candida albicans and 91 cases of non-Candida albicans, of which Candida parapsilosis was the most common (41 cases). Fungal sepsis was independently associated with increased risk of moderate to severe bronchopulmonary dysplasia (BPD) (adjusted OR 1.52, 95%CI 1.04-2.22, P=0.030) and severe retinopathy of prematurity (ROP) (adjusted OR 2.55, 95%CI 1.12-5.80, P=0.025). Previous broad spectrum antibiotics exposure (adjusted OR=2.50, 95%CI 1.50-4.17, P<0.001), prolonged use of central line (adjusted OR=1.05, 95%CI 1.03-1.08, P<0.001) and previous total parenteral nutrition (TPN) duration (adjusted OR=1.04, 95%CI 1.02-1.06, P<0.001) were all independently associated with increasing risk of fungal sepsis. Conclusions: Candida albicans and Candida parapsilosis are the main pathogens of fungal sepsis among preterm infants in Chinese NICU. Preterm infants with fungal sepsis are at increased risk of moderate to severe BPD and severe ROP. Previous broad spectrum antibiotics exposure, prolonged use of central line and prolonged duration of TPN will increase the risk of fungal sepsis. Ongoing initiatives are needed to reduce fungal sepsis based on these risk factors.
Infant ; Infant, Newborn ; Humans ; Birth Weight ; Intensive Care Units, Neonatal ; Retrospective Studies ; Tertiary Care Centers ; Infant, Extremely Low Birth Weight ; Gestational Age ; Infant, Extremely Premature ; Sepsis/epidemiology* ; Retinopathy of Prematurity/epidemiology* ; Bronchopulmonary Dysplasia/epidemiology*