Trends in short-term outcomes of very low birth weight infants from a single center in Shanghai from 2013 to 2023
Highlight box
Key findings
• Mortality and major morbidities of very low birth weight infants (VLBWI) decreased from 2013 to 2023, with the exception of bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) ≥ stage 3.
What is known and what is new?
• With improvements in neonatal and obstetric management and therapy, mortality and morbidity for VLBWI decreased.
• From 2013 to 2023, mortality for VLBWI decreased in our center and morbidities showed different patterns: late onset sepsis, necrotizing enterocolitis ≥ stage 2, intraventricular hemorrhage ≥ grade 3, and periventricular leukomalacia increased. The inflection point occurred around 2017.
What is the implication, and what should change now?
• Continuous research and quality improvement efforts should be undertaken to further improve the outcomes of VLBWI, particularly for BPD and ROP.
Introduction
Despite the optimization of preventive and therapeutic measures, there was no significant change in the preterm birth rate between 2010 and 2020 (9.8% vs. 9.9%) worldwide (1). Meanwhile, there was a gradual increase in the proportion of very low birth weight infants (VLBWI) among preterm infants. A Korean study found that the proportion of VLBWI among preterm infants increased from 0.5% in 2010 to 0.8% in 2020 (2). Members of Vermont Oxford Network contributed data on infants born with birth weight (BW) <1,500 g and at 24 to 28 weeks gestation, which showed that the number increased from 54,695 during 1997–2001 to 97,475 during 2017–2021 (3). Chinese Neonatal Network (CHNN), initiated in 2019, was the first national collaborative network through Chinese major neonatal/perinatal centers, and the primary data from the first year of CHNN report showed that the number of very preterm or VLBWI was 9,552, of which 17.2% were less than 28 weeks gestational age (GA) (4). As the national medical center, we have carried out some quality improvement (QI) projects in our neonatal intensive care unit (NICU) over the past 11 years.
VLBWI are more susceptible to disease and death due to their immaturity. The incidence of complications such as bronchopulmonary dysplasia (BPD), late-onset sepsis (LOS), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and retinopathy of prematurity (ROP) increases with the decreasing BW and GA at birth (3,4). These major morbidities would prolong the hospital stays, affect the long-term prognosis, and increase the psychological and financial burden on their family, which may be also the important reasons for discharge against medical advice in NICU in some developing countries (5,6), including China (7,8). Looking for effective prevention and treatment has become the main challenge for obstetricians and neonatologists. It is necessary to continuously strengthen care processes and develop new strategies to reduce the incidence of major morbidities and improve the poor prognosis for VLBWI. Our study primarily aimed to summarize and analyze the changes in short-term outcomes for infants with BW less than 1,500 g from 2013 to 2023, providing references for VLBWI management and policy planning to improve their short-term outcomes in the future. We present this article in accordance with the STROBE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-16/rc).
Methods
Study population
The study included infants with a BW <1,500 g and GA <37 weeks who were admitted to Children’s Hospital of Fudan University within 7 days of birth from January 2013 through December 2023, regardless of resuscitation status. Infants were followed up until discharge, transfer or death. Data including neonatal demographics and major morbidities during hospitalization were collected. Cases with severe congenital malformations, lack of critical hospitalization records, and discharged against medical advice were excluded. The same diagnostic criteria were applied to all infants. Infants were divided into two subgroups according to BW: <1,000 and 1,000–1,500 g.
Data collection
Demographic, antenatal, and maternal information were extracted from the delivery hospital’s records. Infant characteristics and medical history were obtained from our electronic medical record database. The study cohort was identified by admission time [2013–2023] and diagnosis (VLBWI). To ensure data accuracy, a dual-entry verification process was implemented, in which two independent researchers entered data separately and cross-checked all entries for consistency. Cases with missing critical variables (e.g., GA, BW, or complications) were excluded from the analysis.
Relevant definitions
GA was determined using the hierarchy of best obstetric estimates based on antenatal ultrasonography, menstrual history, obstetric examination, or all 3 factors. Small for gestational age (SGA) was defined as a BW of less than the 10th percentile corresponding to sex and GA (9). Breastfeeding was defined as infants receiving exclusive breastfeeding (mother’s own milk or donor milk) or mixed feeding (breastfeeding combined with any formula milk) during hospitalization. Major morbidity included BPD, defined as ventilation or oxygen dependence at 36 weeks’ corrected age or at discharge, transfer, or death before 36 weeks (10). IVH was defined as greater than or equal to grade 3 according to the Papile criteria (11). LOS was defined as positive blood or cerebrospinal fluid cultures 3 days after admission and antibiotic treatment for 5 days or more. NEC was defined as greater than or equal to stage 2 according to the Bell criteria (12). ROP was diagnosed according to the International Classification of Retinopathy of Prematurity and defined as stage 3 to 5 or requiring treatment (13). PVL was defined as the presence of PVL confirmed by cranial ultrasound or magnetic resonance imaging.
Ethical considerations
The study procedures strictly followed the ethical principles of the Declaration of Helsinki and its subsequent amendments, and were approved by the Research Ethics Board of Children’s Hospital of Fudan University [No. (2024)113]. The need for informed consent was waived by the Research Ethics Board because of the retrospective nature of the study.
Statistical analysis
Statistical and graphical analyses were performed with SPSS 26.0 and R 4.3.1. Results were presented as counts and frequencies (percentages) for categorical variables and as mean [standard deviation (SD)] or median [interquartile range (IQR)] for continuous variables. The chi-square test or Fisher’s exact test was used for categorical variables. A P value <0.05 was considered statistically significant. The 95% confidence interval (CI) for mortality and major morbidities was displayed graphically. Multivariate logistic regression analysis was adjusted for prenatal corticosteroids, mode of delivery, multiple gestation, BW, surfactant administration, breastfeeding, and SGA status.
The Joinpoint Regression Program 5.3.0 software, developed by the National Cancer Institute in the United States, has been widely used to study disease incidence and mortality trends. Annual percentage change (APC) is a measure of the percentage increase or decrease in a variable in a given year. Average annual percent change (AAPC) measures the average yearly change in a variable over the study period. Unlike APC, AAPC looks at general trends over time and eliminates short-term fluctuations, so it is more instructive when assessing long-term trends. In our study, the APC and AAPC were calculated by Joinpoint.
From a statistical standpoint, an APC or AAPC estimate exceeding zero denotes an upward trajectory in the specified interval. In contrast, an APC or AAPC estimate falling below zero signals a downward trend. The Joinpoint also gives 95% CI and P values to assess significance. If the P value is less than 0.05, it is considered statistically significant.
Results
Infants characteristics
A total of 2,713 VLBWI admitted to our hospital were collected. Thirty-two cases with severe congenital malformations, 38 cases with incomplete hospital records, and 168 cases discharged against medical advice were excluded. Characteristics of 2,475 VLBWI born between 2013 and 2023 are shown in Table 1. There were 1,327 males (53.6%) and 1,148 females (46.4%). The median BW was 1,280 [1,040, 1,360] g and the median GA was 29.6 (28.3, 31.0) weeks. There were more extremely low birth weight infants (ELBWI) and extremely preterm infants (EPI) (P=0.001). 76.6% of infants received at least 1 dose of antenatal corticosteroids and 64.6% infants were cesarean deliveries, both of which increased dramatically over the past 11 years (P<0.001). The proportion of SGA infants was 24.1%, showing a decreasing trend from 2013 to 2023 (P=0.007).
Table 1
Characteristics | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | c2 | P value |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sex | 12.549 | 0.25 | |||||||||||
Female | 103 (43.5) | 117 (51.5) | 97 (43.1) | 115 (46.4) | 126 (47.5) | 135 (49.1) | 115 (45.3) | 55 (39.3) | 95 (45.9) | 99 (53.2) | 91 (43.1) | ||
Male | 134 (56.5) | 110 (48.5) | 128 (56.9) | 133 (53.6) | 139 (52.5) | 140 (50.9) | 139 (54.7) | 85 (60.7) | 112 (54.1) | 87 (46.8) | 120 (56.9) | ||
BW | 28.998 | 0.001 | |||||||||||
<1,000 g | 35 (14.8) | 35 (15.4) | 45 (20.0) | 46 (18.5) | 59 (22.3) | 72 (26.2) | 45 (17.7) | 24 (17.1) | 46 (22.2) | 49 (26.3) | 60 (28.4) | ||
1,000–1,500 g | 202 (85.2) | 192 (84.6) | 180 (80.0) | 202 (81.5) | 206 (77.7) | 203 (73.8) | 209 (82.3) | 116 (82.9) | 161 (77.8) | 137 (73.7) | 151 (71.6) | ||
GA | |||||||||||||
<28 W | 43 (18.1) | 31 (13.7) | 55 (24.4) | 49 (19.8) | 74 (27.9) | 68 (24.7) | 62 (24.4) | 31 (22.1) | 53 (25.6) | 54 (29.0) | 72 (34.1) | 37.665 | <0.001 |
28–<30 W | 81 (34.2) | 84 (37.0) | 84 (37.3) | 87 (35.1) | 77 (29.1) | 82 (29.8) | 88 (34.6) | 57 (40.7) | 76 (36.7) | 62 (33.3) | 67 (31.8) | 11.195 | 0.34 |
30–<32 W | 72 (30.4) | 68 (30.0) | 51 (22.7) | 74 (29.8) | 81 (30.6) | 87 (31.6) | 59 (23.2) | 32 (22.9) | 46 (22.2) | 45 (24.2) | 46 (21.8) | 19.358 | 0.04 |
≥32 W | 41 (17.3) | 44 (19.4) | 35 (15.6) | 38 (15.3) | 33 (12.5) | 38 (13.8) | 45 (17.7) | 20 (14.3) | 32 (15.5) | 25 (13.4) | 26 (12.3) | 9.010 | 0.53 |
SGA | 64 (27.0) | 71 (31.3) | 57 (25.3) | 68 (27.4) | 71 (26.8) | 71 (25.8) | 57 (22.4) | 28 (20.0) | 36 (17.4) | 37 (19.9) | 37 (17.5) | 24.179 | 0.007 |
Multiple birth | 95 (40.1) | 65 (28.6) | 81 (36.0) | 93 (37.5) | 111 (41.9) | 109 (39.6) | 95 (37.4) | 47 (33.6) | 86 (41.5) | 64 (34.4) | 81 (38.4) | 14.418 | 0.16 |
Antenatal corticosteroids | 92 (38.8) | 114 (50.2) | 158 (70.2) | 163 (65.7) | 200 (75.5) | 235 (85.5) | 210 (82.7) | 123 (87.9) | 188 (90.8) | 170 (91.4) | 190 (90.0) | 238.468 | <0.001 |
Surfactant | 145 (61.2) | 152 (67.0) | 147 (65.3) | 138 (55.6) | 174 (65.7) | 178 (64.7) | 168 (66.1) | 90 (64.3) | 135 (65.2) | 133 (71.5) | 149 (70.6) | 18.082 | 0.054 |
Cesarean | 142 (59.9) | 143 (63.0) | 123 (54.7) | 150 (60.5) | 164 (61.9) | 184 (66.9) | 160 (63.0) | 92 (65.7) | 145 (70.0) | 134 (72.0) | 162 (76.8) | 36.810 | <0.001 |
Breastfeeding | 71 (29.9) | 65 (28.6) | 160 (71.1) | 214 (86.3) | 238 (89.8) | 258 (93.8) | 243 (95.7) | 130 (92.9) | 182 (87.9) | 135 (72.6) | 191 (90.5) | 770.251 | <0.001 |
Data are presented as n (%). BW, birth weight; GA, gestational age; g, gram; SGA, small for gestational age; VLBWI, very low birth weight infants; W, weeks.
Short-term outcomes
Multivariate logistic regression analysis was adjusted for prenatal corticosteroids, mode of delivery, multiple gestation, BW, surfactant administration, breastfeeding, and SGA status. Only BW remained significantly associated with mortality and major morbidities after adjustment for potential confounders (Tables S1-S7).
Overall, from 2013 to 2023, the mortality of all enrolled VLBWI decreased from 11.4% to 5.2%, LOS decreased from 17.3% to 10.9%, NEC decreased from 9.3% to 4.7%, IVH decreased from 6.7% to 5.0%, and PVL decreased from 5.9% to 3.3%. BPD increased from 18.6% to 28.0% and ROP increased from 2.1% to 5.2%. APCs and AAPCs with 95% CIs for the total VLBWI are shown in Table 2 and by BW in Table 3. Observed rates and fitted trends for the whole population are shown in Figure 1.
Table 2
Outcomes | Trend 1 | Trend 2 | Total period | |||||||
---|---|---|---|---|---|---|---|---|---|---|
Period | APC | 95% CI | Period | APC | 95% CI | AAPC | 95% CI | |||
Mortality | 2013–2017 | −2.83 | −11.49, 6.68 | 2017–2023 | −10.85* | −16.66, −4.63 | −7.47* | −10.16, −4.69 | ||
LOS | 2013–2017 | 0.96 | −8.84, 11.81 | 2017–2023 | −6.90* | −12.61, −0.81 | −3.89* | −7.00, −0.68 | ||
NEC | 2013–2018 | −2.90 | −13.84, 9.43 | 2018–2023 | −17.56* | −30.77, −1.85 | −9.15* | −13.96, −4.08 | ||
IVH | 2013–2017 | 8.43 | −1.60, 19.50 | 2017–2023 | −14.25* | −19.38, −8.80 | −5.91* | −11.26, −0.24 | ||
PVL | 2013–2017 | 10.13 | −6.70, 30.00 | 2017–2023 | −18.63* | −27.70, −8.43 | −8.16* | −15.03, −0.73 | ||
ROP | 2013–2023 | 7.17* | 2.08, 12.52 | – | – | – | 7.17* | 2.08, 12.52 | ||
BPD | 2013–2016 | −11.10 | −28.05, 9.83 | 2016–2027 | 12.33* | 7.16, 17.74 | 6.51* | 2.52, 10.65 |
*, results with statistical significance. AAPC, average annual percent change; APC, annual percent change; BPD, bronchopulmonary dysplasia; CI, confidence interval; IVH, intraventricular hemorrhage; LOS, late-onset sepsis; NEC, necrotizing enterocolitis; PVL, periventricular leukomalacia; ROP, retinopathy of prematurity; VLBWI, very low birth weight infants.
Table 3
Outcomes | Birth weight | Trend 1 | Trend 2 | Total period | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Period | APC | 95% CI | Period | APC | 95% CI | AAPC | 95% CI | ||||
Mortality | <1,000 g | 2013–2016 | 1.70 | −3.42, 19.45 | 2016–2023 | −11.60* | −15.51, −7.51 | −8.46* | −11.36, −5.47 | ||
1,000–1,500 g | 2013–2023 | −11.03* | −16.99, −4.64 | – | – | – | −11.03* | −16.99, −4.64 | |||
LOS | <1,000 g | 2013–2016 | 2.75 | −22.27, 35.82 | 2016–2023 | −16.84* | −23.84, −9.20 | −11.93* | −16.78, −6.80 | ||
1,000–1,500 g | 2013–2023 | −1.52 | −5.06, 2.16 | – | – | – | −1.52 | −5.06, 2.16 | |||
NEC | <1,000 g | 2013–2016 | 40.34 | −52.74, 316.82 | 2016–2023 | −12.85* | −21.28, −3.51 | −8.57* | −15.56, −0.99 | ||
1,000–1,500 g | 2013–2017 | −2.88 | −14.34, 10.12 | 2017–2023 | −11.85* | −19.56, −3.40 | −9.40* | −14.83, −3.62 | |||
IVH | <1,000 g | 2013–2017 | 23.09* | 10.45, 37.17 | 2017–2023 | −13.45* | −17.38, −9.28 | −3.66 | −11.09, 4.40 | ||
1,000–1,500 g | 2013–2023 | −9.66 | −15.05, −3.92 | – | – | – | −9.66* | −15.05, −3.92 | |||
PVL | <1,000 g | 2013–2016 | 32.85 | −8.92, 93.78 | 2016–2023 | −25.89* | −34.37, −16.31 | −11.71* | −21.18, −1.10 | ||
1,000–1,500 g | 2013–2017 | 11.34 | −12.48, 41.63 | 2017–2023 | −15.81* | −27.61, −2.08 | −5.85 | −15.31, 4.67 | |||
ROP | <1,000 g | 2013–2023 | 9.39* | 5.93, 12.97 | – | – | – | 9.39* | 5.93, 12.97 | ||
1,000–1,500 g | 2013–2023 | −4.28 | −14.30, 6.92 | – | – | – | −4.28 | −14.30, 6.92 | |||
BPD | <1,000 g | 2013–2016 | −44.10* | −66.20, −7.54 | 2016–2023 | 12.02* | 5.27, 19.21 | −1.51 | −8.87, 5.64 | ||
1,000–1,500 g | 2013–2023 | 7.45* | 3.29, 11.76 | – | – | – | 7.45* | 3.29, 11.76 |
*, results with statistical significance. AAPC, average annual percent change; APC, annual percent change; BPD, bronchopulmonary dysplasia; BW, birth weight; CI, confidence interval; IVH, intraventricular hemorrhage; LOS, late-onset sepsis; NEC, necrotizing enterocolitis; PVL, periventricular leukomalacia; ROP, retinopathy of prematurity; VLBWI, very low birth weight infants.

For infants receiving full care and treatment, the mortality analysis showed two segments: stable from 2013 to 2017 (APC −2.83, 95% CI: −11.49 to 6.68) and decreasing from 2017 to 2023 (APC −10.85, 95% CI: −16.66 to −4.63). The patterns in ELBWI were consistent with the overall cohort. In the other subgroup, the mortality showed a single decreasing trend over the 11-year period.
The trend of LOS was stable from 2013 to 2017 (APC 0.96, 95% CI: −8.84 to 11.81) and decreased from 2017 to 2023 (APC −6.90, 95% CI: −12.61 to −0.81). A similar trend was observed for infants with a BW less than 1,000 g, which was stable in segment 1 and decreased in segment 2. However, this was not the case for infants with a BW between 1,000 and 1,500 g, where the rates remained stable during the study period.
The analysis for NEC presented two segments: stable from 2013 to 2018 (APC −2.90, 95% CI: −13.84 to 9.43) and decreasing from 2018 to 2023 (APC −17.56, 95% CI: −30.77 to −1.85). The trends for infants in two subgroups were consisted with the overall cohort.
The trend of IVH was stable from 2013 to 2017 (APC 8.43, 95% CI: −1.60 to 19.50) and decreased from 2017 to 2023 (APC −14.25, 95% CI: −19.38 to −8.80). In ELBWI, the trend increased from 2013 to 2017 and decreased from 2017 to 2023, while in the other subgroup it decreased from 2013 to 2023.
The analysis for PVL presented two segments: stable from 2013 to 2017 (APC 10.13, 95% CI: −6.70 to 30.00) and decreasing from 2017 to 2023 (APC −18.63, 95% CI: −27.70 to −8.43). The trends for ELBWI mirrored the overall cohort, while the other subgroup remained stable.
The trend of ROP showed a slowly increasing trend from 2013 to 2023 (APC 7.17, 95% CI: 2.08 to 12.52). A similar trend was also observed in ELBWI, while it remained stable all the time in the other subgroup.
The analysis for BPD showed two segments: stable from 2013 to 2016 (APC −11.10, 95% CI: −28.05 to 9.83) and increasing from 2016 to 2023 (APC 12.33, 95% CI: 7.16 to 17.74). The trend for infants with a BW less than 1,000 g was different, with rates decreasing from 2013 to 2016 and increasing from 2016 to 2023. The trend increased slowly from 2013 to 2023 among infants with a BW between 1,000 and 1,500 g.
Discussion
From the 1990s or 2000s, the number of VLBWI increased in many developed countries (2,3,14). The same trend was also observed in many domestic studies, especially for ELBWI and EPI (15,16). Our results found that the proportion of ELBWI and EPI among VLBWI increased gradually as well, reaching 28.4% and 34.1%, respectively, by 2023. With the improvement of perinatal health awareness, the proportion of SGA among VLBWI decreased from 2013 to 2023, which was lower than that of India (24.1% vs. 30.4%), but still higher than that of the United States (US) (24.1% vs. 12.2%) (17). SGA preterm infants are at risk of short- and long-term excess mortality and morbidity resulting from immaturity and deficient intrauterine growth, intensive antenatal monitoring and management are still required for obstetric care.
Exposure to antenatal corticosteroids has been confirmed to prevent early severe respiratory problems and reduce the risk of IVH and BPD in preterm infants (18,19). In our study, a higher number of mothers (75.8%) received antenatal corticosteroids, which increased to 90% in 2023. Meanwhile, more mothers delivered by cesarean section (64.6%). Though there may be some effects of cesarean on the respiratory and immune systems of newborns (20), it has been associated with reduced risk of brain injury and mortality for smaller preterm infants (21,22). Pulmonary surfactant therapy not only promotes lung maturation, reduces the severity of respiratory distress syndrome, and shortens the duration of mechanical ventilation, but also helps to reduce complications and improve long-term prognosis (23,24). We found that there was a slight increase in the administration of pulmonary surfactant, but without a significant difference. Compared with some high-income countries, our above results continued to lag behind (25), suggesting a need for better communication and discussion between obstetricians, neonatologists, and parents when making active decisions in complex perinatal situations.
According to the joinpoint regression analysis, we found that the inflection point of mortality and major morbidities appeared around 2017, which might be associated with the implementation of the universal two-child policy in 2016 (26). The increase in the number of infants was more significant in 2017 as it took time for the policy to be fully popularized. An increasing birth rate may increase the number of VLBWI admissions, as we have shown above, which do made an impact on the incidence of complications in preterm infants and the implementation of clinical management policy. Besides, neonatal clinical quality control center was established in our hospital in 2017 (27). We have not only improved the existing care practices, but also established new QI measures to increase the survival rate of preterm infants while reducing the incidence of major morbidities.
With the widespread use of antenatal corticosteroids and pulmonary surfactants, as well as improvements in respiratory and circulatory support techniques, the mortality of VLBWI has decreased significantly. In the US, the mortality of VLBWI decreased from 18.1% to 12.4% during 1997–2021 (3). In Japan, the survival of ELBWI was 83.0% in 2005, 88.0% in 2010 and 90.2% in 2015, significantly higher than in other countries (28). With an increase of 2% from 2019, CHNN reported that the survival rate of VLBWI was 88% in 2020 (4). In our study, the mortality of enrolled infants was 8.0%, with a decreasing trend from 2013 to 2023. The trend has become more quick since 2017, which may be related to our policy of strengthening QI in different aspects in response to more VLBWI (29-31).
Preterm birth and low BW are risk factors for neonatal infection (32). We observed a significant decrease in the rate of LOS and NEC, with a particularly marked decrease in NEC, which may be associated to the higher rate of breastfeeding in our center. Data from CHNN in 2020 showed that 70.8% of infants received breast milk (4), which was still lower when compared with the US (91.7%) (33). In our study, 76.2% of VLBWI were breastfed during the hospitalization, increasing dramatically from 2015, reaching over 90% and stabilizing after 2017. We conducted an evidence-based practice for breastfeeding in 2015 and found that breastfeeding in VLBWI is proved to have availability, efficacy and feasibility and clinical significance (30). In 2017, our center established the human milk bank. With the continuous improvement in the process of storage and management, the breastfeeding rate increased by as much as three times from 2013 to 2019, reaching the level of developed countries. Compared to other domestic neonatal centers, we performed better in terms of infection control (34,35). This also demonstrates the effectiveness of our application of evidence-based bundle strategies, including effective hand hygiene, rational use of antibiotics, strict ventilator and central venous management, restriction of invasive operations, investigation and analysis of infection incidents that have occurred, and so on (31). However, no significant change was found in the rate of LOS in infants with a BW of 1,000–1,500 g. Also, the overall incidence of infectious diseases in our center was still higher than that in developed countries (35). As infectious diseases prolong the length of hospital stay and cause severe complications, there is still an urgent need to implement and strengthen effective strategies to prevent the occurrence of infectious diseases and improve the prognosis of VLBWI.
Neurological disorders have the greatest impact on the long-term prognosis of VLBWI. In our center, the incidence of IVH and PVL were 7.9% and 5.8%, respectively, showing a decreasing trend over the 11 years, but more quick since 2017. Similar results were also found in an American multicenter study (3). Around 2016, our center introduced bedside cerebral function monitoring devices and proposed the establishment and application of neonatal neurocritical care unit (NNCU), which is a multidisciplinary subspecialty that combines expertise in neonatology, pediatric neurology, radiology, rehabilitation, surgery, and has led to improved outcomes in newborn that have high risk of neurological injury (29,36). In addition, more attention was paid to gentle care: keeping the mid-line head position, reducing the stimuli of light and voice, avoiding unnecessary procedures, and so on. And the results proved that these QI were effective. Besides, increased rates of antenatal corticosteroids and cesarean may also play important roles (37,38), but more relevant studies are needed to analyze the relationship. In addition to postnatal care, prenatal management also needs to be strengthened, such as prevention of maternal infection, administration of magnesium sulphate, nutritional supplementation, and perinatal monitoring, which would also play an important role in the neuroprotection of these infants.
Despite having the lowest morbidity rate of 3.2%, ROP increased slowly over the 11-year period, particularly in ELBWI. We considered that improved survival rates of ELBW infants, higher prevalence of BPD, and increased use of oxygen therapy maybe the potential causes. Similar results have also been found in some multicenter studies (39,40). Researchers also concluded that lower GA, SGA, multiple birth, severe IVH, patent ductus arteriosus and supplemental oxygen were independent risk factors for ROP treatment (41). However, the incidence of ROP decreased in California and Latin America, which may be associated with different oxygen management and ROP screening guidelines (42,43). ROP is one of the leading causes of visual impairment and blindness in preterm infants and has also been found to be independently associated with neurodevelopmental impairment in early childhood (44,45). Prevention of preterm and foetal growth restriction, judicious use of oxygen and reduced incidence of severe IVH and PDA are promising factors that may help mitigate severe ROP. Regular screening, early diagnosis and treatment are also critical to the management of ROP.
As the most common morbidity, BPD showed a significant increasing trend, with an average annual increase of 6.51%. In the subgroup analysis, the rate of BPD in infants with a BW between 1,000–1,500 g increased by 7.45% per year over 11 years. Zhu et al. also found that the incidence of BPD increased in EPI discharged from 31 provinces in China (46). Also, a study in the United States showed an increasing trend of chronic lung disease in VLBWI from 33.4% in 1997 to 43.3% in 2021 (3). Similar results were observed in a large international cohort from 11 high-income countries (25). BPD is always diagnosed at 28 days after birth or 36 weeks of corrected GA (47). We believed that improved survival in VLBWI/ELBWI may indirectly lead to an increase in the diagnosis of BPD. In addition, to minimize the duration of invasive ventilation, non-invasive continuous positive airway pressure ventilation is used more aggressively and for a longer time, which would also induce the incidence of BPD (48). Other studies have also found that LOS, NEC, and comorbidity with infectious pneumonia are high-risk factors for the development of BPD (49,50). Although the exposure to antenatal corticosteroids and pulmonary surfactant therapy has increased, it seems unlikely to further improve the outcomes currently. Yagui et al. conducted a small retrospective cohort study demonstrating that noninvasive neurally adjusted ventilatory assistance (NIV-NAVA), when used as a post-extubation strategy in ELBWI, significantly reduced extubation failure rates within 72 hours compared to conventional nasal continuous positive airway pressure. However, there was no difference between both groups in the prevalence of BPD (51). Our center implemented NIV-NAVA in 2022 to support earlier extubation in preterm infants. However, due to limited sample size and relatively short implementation period, we are still exploring its feasibility and clinical efficacy. This suggests that better strategies for breath support and more research to develop new therapies for BPD are urgently needed.
Our study has several limitations. First, the data were obtained from a single center with a higher level of neonatal care and may affect the generalizability. Second, as our center is a children’s hospital, infants admitted to our center are all outborns, which may not reflect the condition of inborn infants. Finally, there is a lack of information on long-term follow-up to assess neurodevelopmental, respiratory outcomes.
Conclusions
The study presented the overall characteristics and short-term outcomes of VLBWI in a single center from 2013 to 2023. As QI efforts intensified, a steady improvement in mortality and a decrease in major morbidities, except for BPD and ROP of VLBWI, were observed over the 11 years. More efficacious process measures and treatment strategies are warranted to further improve the outcomes of VLBWI in our hospital and ultimately improve their long-term health and well-being of family.
Acknowledgments
We would like to express our sincere gratitude to all the participants and their guardians, the collaborating clinicians, and other clinical staff, making the research possible.
Footnote
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2025-16/rc
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Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-16/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Research Ethics Board of Children’s Hospital of Fudan University [No. (2024)113]. The need for informed consent was waived by the Research Ethics Board because of the retrospective nature of the study.
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