[Association between time of birth and resuscitation outcomes in extremely preterm infants].

OBJECTIVE: To study whether there are differences in the resuscitation process and early outcomes between the extremely preterm infants delivered on off-hours (6 pm to 8 am of working days, weekends, and national holidays) and those delivered on working hours. METHODS: A retrospective analysis was performed on the medical data of extremely preterm infants who were born in the Peking University Third Hospital from January 1, 2010 to December 31, 2020 and transferred to the neonatal intensive care unit (NICU). According to the time of birth, they were divided into two groups:working hours (n=77) and off-hours (n=98). The resuscitation process and early outcomes were compared between the two groups. RESULTS: Compared with the working hours group, the off-hours group had a significantly lower proportion of infants with the use of full-dose dexamethasone before delivery (P < 0.05) and a significantly higher proportion of infants with a 1-minute Apgar score of < 7, positive pressure ventilation, or tracheal intubation (P < 0.05). The incidence rates of neonatal respiratory distress syndrome and intrauterine pneumonia in the off-hours group were significantly higher than those in the working hours group (P < 0.05). CONCLUSIONS: Extremely preterm infants delivered on off-hours tend to have a low Apgar score at 1 minute after birth, with a higher proportion of infants requiring positive pressure ventilation or tracheal intubation during resuscitation than those delivered on working hours, and they tend to develop neonatal respiratory distress syndrome and intrauterine pneumonia. This suggests that it is important to make adequate preparations in terms of personnel and supplies for resuscitation of extremely preterm infants after birth and that NICUs should develop a detailed management plan for extremely preterm infants at each period of time before, during, and after birth.

[A clinical analysis of hypothyroidism in very low birth weight/extremely low birth weight infants].

OBJECTIVE: To study the risk factors and treatment outcome of hypothyroidism in very low birth weight/extremely low birth weight (VLBW/ELBW) infants. METHODS: The VLBW/ELBW infants who were diagnosed with hypothyroidism from September 2018 to December 2019 were enrolled as the case group (n=29). The children with normal thyroid function, matched at a ratio of 1 : 3, were enrolled as the control group (n=87). Clinical features were compared between the two groups. The correlation of thyroid function with gestational age and birth weight and the risk factors for hypothyroidism were analyzed. RESULTS: A total of 162 VLBW/ELBW infants who met the inclusion criteria were enrolled, with 29 infants in the case group (an incidence rate of hypothyroidism of 17.9%). The lower the birth weight, the higher the incidence rate of hypothyroidism (P<0.05). Triiodothyronine (T3) and free T3 were positively correlated with gestational age (P<0.05). T3 and free thyroxine were positively correlated with birth weight (P<0.05). Small for gestational age, multiple birth, maternal age ≥ 35 years, and use of dopamine were independent risk factors for hypothyroidism (P<0.05). In the case group, 16 infants were treated with levothyroxine (5-10 µg/kg daily), and the thyroid function returned to normal after 2 weeks of treatment. CONCLUSIONS: There is a high incidence rate of hypothyroidism in VLBW/ELBW infants. Small for gestational age, multiple birth, advanced maternal age, and use of dopamine are risk factors for hypothyroidism. The infants treated with levothyroxine should be followed up regularly to ensure an appropriate dose.

[Risk factors for minimally invasive surfactant administration failure in preterm infants with respiratory distress syndrome].

OBJECTIVE: To identify risk factors for minimally invasive surfactant administration (MISA) failure in the treatment of preterm infants with respiratory distress syndrome (RDS) and the influence of MISA failure on neonatal outcome. METHODS: A retrospective analysis was performed for the clinical data of 148 preterm infants with a gestational age of ≤32 weeks and a clinical diagnosis of RDS, who were admitted to the neonatal intensive care unit of eight tertiary hospitals in Beijing, Tianjin and Hebei Province from July 1, 2017 to December 31, 2018 and were treated with MISA (bovine pulmonary surfactant, PS). According to whether MISA failure (defined as the need for mechanical ventilation within 72 hours after MISA) was observed, the infants were divided into two groups: MISA failure group (n=16) and MISA success (n=132). A logistic regression analysis was used to investigate the risk factors for MISA failure and its influence on neonatal outcome. RESULTS: The MISA failure rate was 10.8% (16/148). The logistic regression analysis showed that a high incidence rate of grade >II RDS before PS administration, low mean arterial pressure and high pulse pressure before administration, a low dose of initial PS administration, and long injection time and operation time were the risk factors for MISA failure (OR=5.983, 1.210, 1.183, 1.055, 1.036, and 1.058 respectively, P<0.05). After the control for the above risk factors, the logistic regression analysis showed that the MISA failure group had a significantly higher incidence rate of bronchopulmonary dysplasia (BPD) (OR=8.537, P<0.05). CONCLUSIONS: A high grade of RDS, a low mean arterial pressure, and a high pulse pressure before administration are independent risk factors for MISA failure, and a low dose of initial PS administration, a long injection time, and a long operation time may increase the risk of MISA failure. MISA failure may increase the incidence rate of BPD in preterm infants.

[Prognosis of bronchopulmonary dysplasia in preterm infants: a follow-up during infancy].

OBJECTIVE: To investigate the physical development, incidence of common respiratory diseases, and motor development during infancy in preterm infants with bronchopulmonary dysplasia (BPD). METHODS: A retrospective analysis was performed on the clinical features and infantile outcomes of preterm infants with BPD who were admitted to the neonatal intensive care unit between January 2012 and December 2015. Preterm infants without BPD were used as controls who were admitted to the neonatal intensive care unit during the same period and had similar gestational age and birth weight. Physical development, number of hospital stays, the incidences of pneumonia and wheezing, and motor development during infancy were compared between the two groups. RESULTS: Compared with the control group, BPD infants had a significantly higher incidence of extrauterine growth retardation at discharge (48% vs 41%; P<0.05); BPD infants were more susceptible to pneumonia, wheezing, eczema and rhinitis; BDP infants also had a significantly higher number of readmissions due to respiratory tract infection (P<0.05). BPD infants had a significantly smaller head circumference than the control group at corrected ages of 3, 6, and 12 months (P<0.05). BPD infants had significantly delayed gross, fine, and overall motor development than the control group at corrected ages of 6 and 9 months (P<0.05). CONCLUSIONS: Infants with BPD are susceptible to extrauterine growth retardation at discharge. Their head circumference growth is relatively slow. They are susceptible to pneumonia and wheezing during infancy. Moreover, they have delayed motor development when compared with those without BPD at corrected ages of 6 and 9 months.

[Persistent hypertension for two months in a preterm infant].

A boy aged 2 months (born at 36 weeks of gestation) was admitted due to cough and dyspnea. After admission, he was found to have persistent hypertension, proteinuria, and persistent convulsion, and imaging examination showed extensive calcification of the aorta and major branches and stenosis of local lumens of the abdominal aorta and the right renal artery with increased blood flow velocity. The boy was admitted during the neonatal period due to wet lung and pulmonary arterial hypertension and was found to have hypertension and proteinuria. High-throughput whole-exome sequencing was performed and found two compound heterozygous mutations in the ENPP1 gene from his parents, c.130C>T (p.Q44X) and c.1112A>T (p.Y371F). c.130C>T was a nonsense mutation, which could cause partial deletion of protein from 44 amino acids, and was defined as a primary pathogenic mutation. c.1112A>T was a missense mutation which had been reported as a pathogenic mutation associated with idiopathic infantile arterial calcification (IIAC). Therefore, he was diagnosed with IIAC. He was given phosphonate drugs, antihypertensive drugs, anticonvulsion treatment, and respiratory support. Blood pressure was maintained at the upper limit of normal value. There was no deterioration of arterial calcification. It is concluded that IIAC should be considered for infants with persistent hypertension and extensive vascular calcification, and imaging and genetic examinations should be performed as early as possible to make a confirmed diagnosis.

Structure analysis of transposons carrying the aac(6')-aph(2″) gene in Enterococcus faecalis isolated in Beijing, China, and comparison of their transfer efficiency.

Transfer of aac(6')-aph(2″) transposons mediating high-level gentamicin resistance (HLGR) in Enterococcus faecalis is a serious problem in the clinic. However, factors affecting the transfer of aac(6')-aph(2″) have not yet been elucidated. The current study aimed to examine the genetic and molecular basis of HLGR in E. faecalis strains isolated in Beijing (China) and to clarify the relationship between transfer efficiency of aac(6')-aph(2″) transposons and the transposon structure/location. A total of five transposon structures were identified by PCR mapping of the corresponding transposon regions, including a Tn5281-like non-truncated transposon and four truncated transposons. A plasmid location study of aac(6')-aph(2″) by Southern blot following S1-PFGE and filter mating conjugation experiments demonstrated that plasmid location rates correlated with conjugation-positive rates. Chromosome walking to identify the sequence upstream of a representative type III truncated transposon found a truncated aph(2″)-Ia region, and further PCR analysis of this region among strains from different groups revealed similar a positive rate trend as the transposon plasmid location rate and conjugation-positive rate. In conclusion, aac(6')-aph(2″) transposons were of different structures in E. faecalis strains from Beijing, with two new transposon structures that have not been reported elsewhere. Presence of the truncated aph(2″)-Ia region upstream of some truncated transposons suggests recombination between aminoglycoside-modifying enzyme genes. Possible links exist among plasmid location, conjugation and the presence of truncated aph(2″)-Ia upstream of the transposon.

Multi-center Study of Enteral Feeding Practices in Hospitalized Late Preterm Infants in China.

OBJECTIVE: To investigate the current enteral feeding practices in hospitalized late preterm infants in the Beijing area of China. METHODS: A multi-center, cross-sectional study was conducted. Infants born after 34 weeks and before 37 weeks of gestation were enrolled from 25 hospitals in the Beijing area of China from October 2015 to October 2017. Data on enteral feeding practices were collected and analyzed. RESULTS: A total of 1,463 late preterm infants were enrolled, with a mean gestational age (GA) of 35.6 (34.9, 36.1) weeks. The percentage of exclusive breastfeeding was 4.5% at the initiation of enteral feeding but increased to 14.4% at discharge. When human milk was not available, most infants (46.1%) were fed with preterm infant formula. The rate of exclusive human milk feeding in infants born at 34 weeks gestation was higher than at discharge (21.1% of infants born at 34 weeks' GA versus 12.1% of infants born at 35 weeks' GA versus 12.3% of infants born at 36 weeks' GA, P < 0.001). Only 28.4% of late preterm infants achieved full enteral feeding at discharge, and only 19.2% achieved 120 kcal/(kg•d) by enteral feeding at discharge. Importantly, 40.5% of infants did not regain the birth weight at discharge. CONCLUSION: Enteral feeding support of late preterm infants has not been standardized to achieve optimal growth. Moreover, the human milk feeding rate was low, and many late preterm infants did not achieve the goal of enteral feeding and failed to regain birth weight at the time of discharge. More aggressive enteral feedings protocols are needed to promote human milk feeding and optimize growth for late preterm infants.

[A survey of pubertal development in children born with assisted reproductive technology].

OBJECTIVE: To investigate the status of pubertal development in children born with assisted reproductive technology (ART). METHODS: A retrospective analysis was performed on the pubertal development data of children born with ART in Peking University Third Hospital from 1994 to 2003 (ART group). The data in the cross-sectional study "Reports on the Physical Fitness and Health Research of Chinese School Students in 2010" were used as a control. The age at menarche and the age at spermarche were compared between the two groups. The status of pubertal development in the overweight and obese children in the ART group was evaluated to investigate the correlation between pubertal development and body mass index (BMI). RESULTS: A total of 200 children born with ART were enrolled in this study, and 72 of them (41 males and 31 females) completed the survey (response rate=36.0%). In the ART group, the mean age at spermarche and the mean age at menarche were 13.9 years (95%CI: 13.7-14.3 years) and 12.2 years (95%CI: 11.8-12.6 years), respectively. There were no significant differences in the age at spermarche and the age at menarche between the ART and control groups (P>0.05). In the ART group, there were no significant differences in the age at spermarche and the age at menarche between the overweight and obese children and the normal weight children (P>0.05). There were also no significant differences in overweight rate and obesity rate between the children in the ART group and the adolescents in Beijing (P>0.05). In the ART group, there was no significant correlation between the age at spermarche or menarche and BMI (P>0.05). CONCLUSIONS: No delayed or precocious puberty is observed in children born with ART. This is consistent with the normal control data. And there is no significant correlation between pubertal development and BMI in children born with ART.

Paenibacillus populi sp. nov., a novel bacterium isolated from the rhizosphere of Populus alba.

A novel aerobic bacterium, designated strain LAM0705(T), was isolated from the rhizosphere of Populus alba in the Peking University Third Hospital. Cells of strain LAM0705(T) were observed to be Gram-stain positive, motile, spore-forming and rod-shaped. The optimal temperature and pH for growth were found to be 30 °C and pH 7.5, respectively. Strain LAM0705(T) was found to be able to grow in the presence 0-5 % NaCl (w/v) (optimum 1.0 %). The major fatty acids of strain LAM0705(T) were identified as anteiso-C15:0, C16:0 and iso-C16:0. The dominant polar lipids were found to consist of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The cell wall peptidoglycan of strain LAM0705(T) was found to contain meso-diaminopimelic acid. The predominant menaquinone was identified as MK-7. The G+C content of genomic DNA was found to be 48 mol% when determined by the T m method. The 16S rRNA gene sequence similarity analysis indicated that strain LAM0705(T) is closely related to Paenibacillus agaridevorans DSM 1355(T) and Paenibacillus thailandensis KCTC 13043(T) with 97.8 and 96.1 % sequence similarity, respectively. The DNA-DNA hybridization value between strain LAM0705(T) and P. agaridevorans DSM 1355(T) was 47 ± 0.8 %. On the basis of its phenotypic, phylogenetic and chemotaxonomic characteristics, strain LAM0705(T) is concluded to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus populi sp. nov. is proposed. The type strain is LAM0705(T) (=ACCC 06427(T) = JCM 19843(T)).

[Clinical features of respiratory diseases in late preterm neonates].

OBJECTIVE: To evaluate the clinical features of respiratory diseases of late preterm neonates. METHODS: Six hundred and thirty late preterm infant(gestational age: 34~36+6weeks),4401 cases of term infants and 328 early preterm infants who were born at the obstetrical department of Peking University 3rd Hospital from January 2009 to December 2010 were enrolled. Among them 84 late preterm infants, 135 term infants and 182 early preterm infants developed respiratory diseases. The incidence of respiratory diseases,clinical features and the severity of the diseases were compared among the three groups. RESULTS: The incidence and mortality rates of respiratory diseases and the percentage of severe cases were significantly higher in the late preterm group than in the term group, but lower than in the early preterm group (P<0.01). The symptoms of respiratory disease occurred earlier in the late preterm group than in the term group, but later than in the early preterm group (P<0.01). The late preterm group had a significantly higher incidence of tachypnea and lower incidence of retraction sign when compared with the term and early preterm groups (P<0.05). The percentages requiring oxygen therapy and mechanical ventilation in the late preterm group were both significantly higher than in the term group, but lower than in the early preterm group (P<0.05). The multiple linear regression analysis showed 11 factors associated with the severity of respiratory diseases: decreased arterial partial pressure of oxygen, hematokrit, pH value and respiratory rate, arterial oxyhemoglobin saturation, systolic arterial pressure, 5 minute Apgar score and gestational age, and increased blood urea nitrogen, heart rate and respiratory rate. CONCLUSIONS: Late preterm infants are more likely to develop respiratory diseases than term infants, and to develop a more severe condition and need a more intensive respiratory support treatment. Tachypnea is a common presentation of dyspnea in late preterm infants and occurs earlier than in term infants but later than in early preterm infants. It may usually indicate a serious condition when dyspnea, abnormal heart rate and blood pressure, and multisystem damages occur in late preterm infants.

[Relationship between ACE gene insertion or deletion polymorphism and left ventricular mass in newborns admitted to the neonatal intensive care unit].

OBJECTIVE: To study the relationship between angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and left ventricular mass (LVM) in newborns admitted to the neonatal intensive care unit (NICU). METHODS: Seventy-two newborns admitted to the NICU were enrolled. ACE genotypes were determined by genomic DNA which was isolated from heel-prick blood. Disease status of the newborns was evaluated by the Neonatal Critical Score (draft) on postnatal day 1. LVM and LVM index (LVMI) were evaluated by echocardiography on postnatal days 1-3. RESULTS: DD genotype was identified in 11 cases, ID genotype in 31 cases, and II genotype in 30 cases. There were no significant differences in clinical characteristics, critical score and body measurements in newborns with different genotypes. The DD genotype group showed significantly lower LVMI than the group with ID+II genotypes (29±4 g/m2 vs 35±8 g/m2; P<0.05). CONCLUSIONS: ACE gene polymorphism is associated with the LVMI in newborns admitted to the NICU. The LVMI of DD genotype carriers is significantly lower than that of ID+II genotypes carriers, which suggests that D allele may be associated with the growth and development of left ventricular.

No Weight Catch-Up Growth of SGA Infants Is Associated with Impaired Insulin Sensitivity during the Early Postnatal Period.

Objective. To investigate the relationship between weight catch-up growth and insulin sensitivity in small for gestational age (SGA) infants. Methods. Forty-four singleton SGA subjects met the inclusion criteria and finished-3-month followup. Body weight, length, fasting glucose, and fasting insulin (FI) levels were measured at 3 days and 3 months. Insulin sensitivity was evaluated by FI and homeostasis model assessment (HOMA). Results. According to the change of weight Z-score, forty-four subjects were divided into two groups: noncatch-up growth (NCUG) and catch-up growth (CUG). By 3 months of age, the body weight, body length and BMI of NCUG group were significantly lower than those of CUG group. The FI and HOMA were significantly higher in NCUG group. The change of weight Z-score during 3 months was inversely related to the HOMA at 3 months. Conclusion. Our data exemplified that no weight catch-up growth during the first 3 months was associated with impaired insulin sensitivity in SGA infants.

[Serum gastrin levels and clinical conditions in response to early minimal feeding in premature infants].

OBJECTIVE: To study serum gastrin levels in response to early minimal feeding in premature infants and evaluate the clinical effect of early minimal feeding. METHODS: Premature infants with critical score < or = 90 were randomly assigned into two groups: early minimal feeding group (n = 48), non-early minimal feeding group (n = 47). Other premature infants (n = 30) without any complications (critical score > 90) were assigned as normal control group. The premature infants in normal control group were fed with water at 6 h after birth, 1 - 2 ml/kg every time, after once or twice, they were fed with formula, increasing in the amount of formula gradually, until adequate. The premature infants in early minimal feeding group were fed with formula within 72 h after birth, 0.5 - 1 ml/kg, once every 3 h, the amount of formula was increased gradually, until adequate. The premature infants without early minimal feeding were not fed with formula until the illness was stable, the amount of formula was increased gradually until adequate. Situation of gastrointestinal feeding tolerance, growth and development, and clinical symptoms were observed and recorded for the three groups. Serum gastrin levels were monitored at 1, 3, 7 day after birth by radioimmunoassay. RESULTS: Serum gastrin concentrations in the three groups elevated from 1 to 7 days. In early minimal feeding group [(82.4 +/- 24.5) ng/L] and non-early minimal feeding group [(87.0 +/- 40.2) ng/L], the concentrations were significantly higher than those in normal control group [(66.4 +/- 19.7) ng/L] at day 1 (F = 3.36, P < 0.05). At day 3 and 7, the concentrations in early minimal feeding group [(96.3 +/- 14.6) ng/L, (113.0 +/- 16.5) ng/L] were significantly higher than those in non-early minimal feeding group [(73.9 +/- 13.5) ng/L, (92.4 +/- 12.2) ng/L] (P < 0.05). There were significant differences among the three groups in infants with feeding intolerance (2/30, 5/48, 14/47), the period reached full enteral feeding [(20.6 +/- 5.7) d, (27.8 +/- 6.1) d, (39.5 +/- 4.7) d], and in number of hospital day [(29.0 +/- 4.6) d, (39.0 +/- 4.8) d, (48.0 +/- 5.6) d] (P < 0.05). There were significant differences between early minimal feeding group and non-early minimal feeding group in the weight gain three and four weeks after birth [(19.1 +/- 2.4) g/d, (11.9 +/- 3.3) g/d], the period reached birthweight [(19.8 +/- 4.2) d, (25.2 +/- 5.1) d] (P < 0.05). There were no significant difference among the three groups in the weight gain in one and two weeks after birth [(5.9 +/- 2.9) g/d vs. (5.0 +/- 2.1) g/d], the numbers of premature infants with infection, anemia, apnea, or hypoglycemia. CONCLUSION: Early minimal feeding in premature infants leads to secretion of gastrin, promotes the development of gastrointestine and may not be associated with occurrence of complications.

[Influence of angiotensin converting enzyme gene insertion/deletion polymorphism and beta3-adrenergic receptor gene Trp64Arg polymorphism on fetal growth and neonatal insulin sensitivity].

OBJECTIVE: To understand the influence of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and beta3-adrenergic receptor (beta3-AR) gene Trp64Arg polymorphism on fetal growth and neonatal insulin sensitivity. METHODS: Totally 296 newborn infants were selected into our study and divided into 2 groups according to gestational age and birth weight: adequate-for-gestational-age (AGA) group (222 cases) and small-for-gestational-age (SGA) group (74 case). Serum glucose and insulin were examined in the morning of the 3rd day before milk. Insulin sensitivity was evaluated by homeostasis model assessment (HOMA) equation. beta3-AR gene Trp64Arg polymorphism and ACE gene I/D polymorphism (202 cases) were analysed using polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) technique. Gestational age, birth weight, birth weight percentage, serum glucose, insulin and HOMA-IR were compared among different genotype groups. Statistical analysis was performed with the SPSS 10.0 software. RESULTS: No significant difference was found between the serum glucose level of SGA group (4.03 +/- 1.05 mmol/L) and AGA group (4.05 +/- 1.14 mmol/L), P = 0.008. The serum insulin level (converted into Ln) of SGA group (2.262 +/- 0.746) was significantly higher than that of AGA group (1.757 +/- 0.805), P < 0.001. The HOMA-IR (also converted into Ln) level of SGA group (0.217 +/- 0.367) was also significantly higher than that of AGA group (0.001 +/- 0.378), P < 0.001. In the SGA group beta3-AR gene Arg64 allele carriers had higher serum insulin and HOMA-IR level (both changed to Ln, 2.654 +/- 0.701, 0.371 +/- 0.338) compared with noncarriers (2.074 +/- 0.698, 0.143 +/- 0.360), P < 0.05. The ACE gene DD genotype carriers had higher serum insulin and HOMA-IR level (both were converted into Ln, 2.19 +/- 0.91, 0.51 +/- 1.01) compared with II (1.77 +/- 0.85, 0.02 +/- 0.93) and ID genotype group (1.77 +/- 0.83, 0.05 +/- 0.91), P < 0.05. The ACE gene DD carriers had lower birth weight percentage compared with II and ID genotype group, P < 0.05. When both genes' polymorphisms were taken into account, the newborns who had both DD genotype and Arg64 allele had obviously higher serum insulin level (Ln, 2.560 +/- 1.160) than the neonates who had only one of the polymorphisms mentioned above (1.970 +/- 0.821, 1.992 +/- 0.706) and the neonates who had neither of the two polymorphisms (1.683 +/- 0.832), P < 0.05. The newborns who had both DD genotype and Arg64 allele also had significantly higher HOMA-IR level (Ln, 1.042 +/- 1.315) than the neonates who had only one of the polymorphisms mentioned above (0.247 +/- 0.710, 0.230 +/- 0.890) and the neonates who had neither of the two polymorphisms (-0.053 +/- 0.924), P < 0.05. CONCLUSION: Newborns SGA had impaired insulin sensitivity. beta3-AR gene Trp64Arg polymorphism and ACE gene I/D polymorphism are important factors that may connect IUGR with insulin resistance syndrome in adulthood.

[Relationship of the disease severity with ACE gene polymorphism and serum ACE activity in preterm infants].

OBJECTIVE: To investigate the relationship of disease severity with angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and serum ACE activity in preterm infants during the first 7 days of life. METHODS: ACE genotypes were determined in 85 preterm infants admitted to the neonatal intensive care unit (NICU). Serum ACE activity was measured and disease severity was evaluated by the Neonatal Critical Score (draft) 1, 3 and 7 days after birth. RESULTS: Of the 85 preterm infants, DD genotype was found in 19 cases, ID genotype in 34 cases and II genotype in 32 cases. On the 1st day of life, serum ACE activity in the DD genotype (33.42+/-7.93 U/L) and the ID genotype groups (31.53+/-7.56 U/L) were significantly higher than that in the II genotype group (25.53+/-7.56 U/L) (P<0.01). After 3 and 7 days of life, serum ACE activity decreased in the three groups, but the DD genotype group remained the highest ACE activity, followed by the ID genotype and the II genotype groups. On the 1st day of life, the critical score of the DD genotype group (87.37+/-8.30) was lower than the ID genotype (95.82+/-5.85) and the II genotype groups (95.88+/-6.85) (P<0.01). On the 3rd day, the critical score of the DD genotype group was still lower than the ID genotype group (92.95+/-7.10 vs 96.94+/-5.85) (P<0.05). CONCLUSIONS: ACE gene I/D polymorphism may be associated with the disease severity in preterm infants. The DD genotype carriers present more severe disease status, with higher serum ACE activity. Although the disease status can influence serum ACE activity, serum ACE activity is determined by the ACE genotype.