Preterm birth and asthma and COPD in adulthood: a nationwide register study from two Nordic countries

Research priorities for preterm lung health research across the lifespan: a community priority setting partnership

BACKGROUND

It is essential to embed patient and public perspectives into every stage of the research journey, including setting the future research agenda. The substantial gaps in our understanding of prematurity-associated lung disease presented a timely opportunity to determine the community's research priorities.

OBJECTIVE

To conduct a priority setting partnership (PSP) to determine the top 10 research priorities for preterm lung health.

DESIGN

We undertook a modified James Lind Alliance methodology comprising three main stages: (1) an idea generating survey with open questions to ascertain the community's most important ideas for future preterm lung health research, (2) prioritisation survey to distill the main themes into a shortlist of 20 and (3) consensus workshop where participants were tasked with ranking their final top 10. This PSP is reflective of the view of preterm-born individuals, parents of preterm children and healthcare professionals in an Australian healthcare setting.

RESULTS

We collated 144 submissions from the idea generating survey from which 27 prioritisation themes were developed. From the 150 prioritisation survey responses, the 20 themes receiving the most votes were taken to the consensus workshop. Participants identified the following top 10: (1) lifelong impacts; (2) interventions, treatments or supports; (3) ongoing lung health follow-up; (4) diagnostic tools, resources and education for primary healthcare providers; (5) resources to inform and empower families; (6) relationship to physical health and developmental issues; (7) preventing and/or treating lung infections; (8) additional supports, resources and research for minority groups; (9) impact on mental well-being; and (10) likelihood of asthma diagnosis.

CONCLUSION

Priorities identified through the PSP will be invaluable in informing future research into prematurity-associated lung disease.

Device-measured physical activity in adults born preterm with very low birth weight and mediation by motor abilities

Physical activity (PA) is beneficial for several health outcomes. Adults born with very low birth weight (VLBW<1500g) undertake less PA than those born at term, have poorer motor abilities and may serve as a model on early life origins of PA. We therefore examined whether motor abilities mediate the association between being born with VLBW and device-measured PA. In a joint assessment of two longitudinal birth cohorts from Finland and Norway, PA was measured by two tri-axial accelerometers in 87 adults born preterm with VLBW and 109 controls born at term. We explored the mediating role of motor abilities assessed by standardized tests on the association between VLBW and device-measured PA. To do this, we examined group differences in metabolic equivalent of task (MET) min/day of moderate to vigorous PA (MVPA), light PA and sedentary. Analyses were adjusted for cohort, age and sex. MVPA was 40.4 (95% confidence interval [CI]: 13.3 to 69.4) MET min/day lower in the VLBW group than the control group. This was in part mediated through gross motor abilities, indicated by the indirect effect on the association between VLBW and MVPA being -15.6 (95% CI: -28.5 to -5.4) MET min/day. In conclusion, adults born preterm with VLBW undertake less MVPA than controls born at term, and gross motor abilities mediate this association. Interventions targeting motor abilities should be examined as potential ways to increase PA.

Health Outcomes 50 Years After Preterm Birth in Participants of a Trial of Antenatal Betamethasone

BACKGROUND AND OBJECTIVES

Preterm birth results in neonatal and childhood morbidity and mortality. Additionally, population-based studies show poorer cardiovascular health in adult survivors, but a full range of health outcomes has not been investigated into midlife. We aimed to assess the health outcomes after preterm vs term birth at 50 years in survivors of a randomized trial of antenatal betamethasone.

METHODS

Participants were asked to complete a health questionnaire and for consent to access administrative data. Participants deceased prior to follow-up were assessed with administrative data alone. The primary outcome was a composite: any of diabetes mellitus, prediabetes, treated hypertension, treated dyslipidemia, or a previous major adverse cardiovascular event. Secondary outcomes included respiratory, mental health, educational, and other health outcomes.

RESULTS

We included 470 participants: 424 assessed at mean age 49.3 years and 46 who died after infancy. The primary outcome occurred in 34.5% (112/325) of those born preterm and 29.9% (43/144) of those born at term; adjusted relative risk (aRR) 1.14 (95% CI, 0.85-1.54; P = .37). Cardiovascular events were less common in those born preterm (9/326 [2.8%] vs 10/144 [6.9%]; aRR 0.33, 95% CI, 0.14-0.79), while self-reported hypertension was more common (101/291 [34.7%] vs 23/116 [19.8%]; aRR 1.74, 95% CI, 1.16-2.61), although treated hypertension was not statistically significantly different (66/323 [20.4%] vs 22/143 [15.4%]; aRR 1.32, 95% CI, 0.84-2.06). Other components of the composite endpoint were similar between those born preterm and at term.

CONCLUSIONS

Those aged 50 years born preterm were more likely to have hypertension but had similar risk of diabetes, prediabetes, and dyslipidemia than those born at term, and their risk of cardiovascular events was lower.

Falling through the cracks: what happens to survivors of preterm birth?

There needs to be increased awareness of the long-term implications of prematurity to ensure optimal follow-up of these babies and design studies to obtain an evidence base for the development of improved guidelines https://bit.ly/46cdVtJ.

Association between preterm birth and asthma and atopic dermatitis in preschool children: a nationwide population-based study

Asthma and atopic dermatitis (AD) are representative chronic diseases in childhood. This study aimed to investigate the impact of preterm birth on the incidence and severity of asthma and AD in children, as well as to identify neonatal risk factors for asthma and AD. We used health claims data recorded between 2007 and 2014 in the Korean National Health Insurance Service database. We recruited 2,224,476 infants born between 2007 and 2014 and divided them into three groups: 3518 of extremely preterm (EP) infants (< 28 weeks of gestational age (GA)), 82,579 of other preterm (OP) infants (28-36 weeks of GA), and 2,138,379 of full-term (FT) infants (> 37 weeks of GA). We defined asthma as > 3 episodes of clinical visits in a year before 6 years of age, early asthma as onset at < 2 years of age, and severe asthma as > 1 event of status asthmaticus or admission to a hospital via an emergency room. AD was defined as ≥ 3 diagnoses in a year before 6 years of age, early AD as onset at < 2 years of age, and severe AD as prescription of high-potency topical steroids or immunosuppressants. An association of preterm birth with asthma and AD was assessed using inverse probability of treatment-weighted multivariable Cox regression analysis. Cardiorespiratory conditions, such as respiratory distress syndrome, bronchopulmonary dysplasia, patent ductus arteriosus, and pulmonary hypertension, significantly increased the risk of asthma. Specifically, bronchopulmonary dysplasia emerged as a significant risk factor for both severe and early-onset asthma (odds ratio (OR) 1.36, 95% CI 1.21-1.37 for severe asthma; OR 1.55, 95% CI 1.30-1.85 for early asthma), while it was associated with a decreased risk of AD (OR 0.86, 95% CI 0.80-0.92). Neonatal sepsis, jaundice, and retinopathy of prematurity were also identified as significant risk factors for later asthma. A stepwise increase in the risk of asthma with an increasing degree of prematurity was observed, with the OP group showing an adjusted hazard ratio (aHR) of 1.24 (95% CI: 1.22-1.26) and the EP group showing an aHR of 1.51 (95% CI: 1.41-1.63). Conversely, preterm birth was inversely associated with the risk of AD, with aHRs of 0.73 (95% CI: 0.67-0.79) for the OP group and 0.88 (95% CI: 0.87-0.89) for the EP group. Conclusion Preterm children have a significantly higher risk of asthma and lower risk of AD, with cardiorespiratory conditions significantly increasing the risk of asthma. Thus, we highlight the need for targeted respiratory management strategies for this high-risk population. What is Known: •Asthma and atopic dermatitis are prevalent chronic diseases in childhood, reducing the quality of life of children. •Preterm birth was associated with an increased risk of asthma, but few large nationwide studies. •Research on the relationship between preterm birth and pediatric atopic dermatitis is controversial, with few large nationwide studies. What is New: • Preterm children, especially born before 28 weeks of gestational age, had a significantly higher risk of asthma and lower risk of atopic dermatitis. • Cardiorespiratory comorbidities such as RDS, BPD, PDA, and pulmonary hypertension in neonatal period are prominent risk factors for asthma. • Preterm children are vulnerable to both early-onset and severe asthma.

General health and social outcomes 50 years after exposure to antenatal betamethasone: follow-up of a randomised controlled trial

BACKGROUND

Antenatal corticosteroids are recommended for women at risk of preterm birth from 24 to 34 weeks' gestation as they reduce neonatal morbidity and mortality, but evidence regarding their long-term effects on offspring is limited. This study assessed general health and social outcomes 50 years after antenatal exposure to corticosteroids.

METHODS

We assessed 424 adult offspring of women who participated in the first randomised, double-blind, placebo-controlled trial of antenatal betamethasone for the prevention of neonatal respiratory distress syndrome. The first 717 mothers received two intramuscular injections of betamethasone (6 mg betamethasone sodium phosphate and 6 mg betamethasone acetate) or placebo given 24 h apart and the subsequent 398 received two injections of double dose betamethasone (12 mg betamethasone sodium phosphate and 12 mg betamethasone acetate) or equivalent volume of placebo. Follow-up included a health questionnaire and consent for access to administrative data sources. Outcome categories included mental health (depression, anxiety, bipolar affective disorder, schizophrenia and treatment or hospital admission for any mental health disorder), general health (chronic kidney disease, cancer diagnosis, bone fracture, oral health, allergies, functional difficulties and physical activity) and social outcomes (educational attainment, employment and criminal convictions). Investigators remained blinded to treatment allocation. Analyses were adjusted for gestational age at entry, sex and clustering.

RESULTS

We assessed 424 adult offspring (46% of survivors; mean [SD] age 49.3 [1.0] years; 212 [50%] female). There was no difference in mental health, general health and social outcomes between those exposed to betamethasone and those exposed to placebo, with the exception that osteoporotic site fracture in adulthood was more likely to have occurred in the betamethasone group compared with placebo (adjusted relative risk 1.57, 95% CI 1.00, 2.48, p = 0.05). No dose-effect relationship was evident and there was no difference in the proportion with at least one fracture. Follow-up rate and lack of in-person assessments were the main limitations.

CONCLUSIONS

There is no evidence that antenatal corticosteroids have clinically important effects on general health and social outcomes up to 50 years of age.

Similarities of metabolomic disturbances in prematurity-associated obstructive lung disease to chronic obstructive pulmonary disease

Prematurity-associated lung disease (PLD) is a long-term consequence of preterm-birth. Since the underlying mechanisms of PLD remain poorly characterised, we compared the urinary metabolome between recently described spirometry phenotypes of PLD. Preterm- and term-born children aged 7-12 years, from the Respiratory Health Outcomes in Neonates (RHiNO) cohort, underwent spirometry and urine collection. The urinary metabolome was analysed by gas chromatography time-of-flight mass spectrometry. Preterm-born children were classified into phenotypes of prematurity-associated obstructive lung disease (POLD, Forced expiratory volume in 1 s (FEV1) < lower limit of normal (LLN), FEV1/Forced Vital Capacity (FVC) < LLN), prematurity-associated preserved ratio impaired spirometry (pPRISm, FEV1 < LLN, FEV1/FVC ≥ LLN) and Preterm/Term controls (FEV1 ≥ LLN). Metabolite set enrichment analysis was used to link significantly altered metabolites between the groups with metabolic pathways. Univariable and multivariable linear regression models examined associations between early and current life factors and significantly altered metabolites of interest. Urine from 197 preterm- and 94 term-born children was analysed. 23 and 25 were classified into POLD and pPRISm groups respectively. Of 242 identified metabolites, 49 metabolites were significantly altered in the POLD group compared with Preterm controls. Decreased capric acid (log2 fold change - 0.23; p = 0.003), caprylic acid (- 0.18; 0.003) and ceratinic acid (- 0.64; 0.014) in the POLD group, when compared to preterm controls, were linked with reduced β-oxidation of very long chain fatty acids (p = 0.004). Reduced alanine (log2 fold change - 0.21; p = 0.046), glutamic acid (- 0.24; 0.023), and pyroglutamic acid (- 0.17; 0.035) were linked with decreased glutathione metabolism (p = 0.008). These metabolites remained significantly associated with POLD in multivariable models adjusting for early/current life factors. The pPRISm urinary metabolome was minimally changed when compared with preterm-born controls. When compared to term-born subjects, alterations in tryptophan metabolism were implicated (p = 0.01). The urinary metabolome in POLD showed significantly altered β-oxidation of fatty acids and glutathione metabolism, implying alterations in cellular metabolism and oxidative stress. Similar findings have been noted in adults with chronic obstructive pulmonary disease. Given the similarity of findings between the POLD group and those reported for COPD, the POLD group should be considered at future risk of developing COPD.

Activated eosinophils in early life impair lung development and promote long-term lung damage

Exaggeration of type 2 immune responses promotes lung inflammation and altered lung development; however, eosinophils, despite expansion in the postnatal lung, have not been specifically assessed in the context of neonatal lung disease. Furthermore, early life factors including prematurity and respiratory infection predispose infants to chronic obstructive pulmonary disease later in life. To assess eosinophils in the developing lung and how they may contribute to chronic lung disease, we generated mice harboring eosinophil-specific deletion of the negative regulatory enzyme SH2 domain-containing inositol 5' phosphatase-1. This increased the activity and number of pulmonary eosinophils in the developing lung, which was associated with impaired lung development, expansion of activated alveolar macrophages (AMφ), multinucleated giant cell formation, enlargement of airspaces, and fibrosis. Despite regression of eosinophils following completion of lung development, AMφ-dominated inflammation persisted, alongside lung damage. Bone marrow chimera studies showed that SH2 domain-containing inositol 5' phosphatase-1-deficient eosinophils were not sufficient to drive inflammatory lung disease in adult steady-state mice but once inflammation and damage were present, it could not be resolved. Depletion of eosinophils during alveolarization alleviated pulmonary inflammation and lung pathology, demonstrating an eosinophil-intrinsic effect. These results show that the presence of activated eosinophils during alveolarization aggravates AMφs and promotes sustained inflammation and long-lasting lung pathology.

Outdoor Air Pollution and Pediatric Respiratory Disease

Outdoor air pollution is ubiquitous, and no safe level of exposure has been identified for the most common air pollutants such as ozone and particle pollution. Children are uniquely more susceptible to the harms of outdoor air pollution, which can cause and exacerbate respiratory disease. Although challenging to identify the effects of outdoor air pollution on individual patients, understanding the basics of outdoor air pollution is essential for pediatric respiratory health care providers. This review covers basic information regarding outdoor air pollution, unique considerations for children, mechanisms for increased susceptibility, and association with incident and exacerbation of respiratory disease in children.

The Influence of Premature Birth on the Development of Pulmonary Diseases: Focus on the Microbiome

Globally, around 11% of neonates are born prematurely, comprising a highly vulnerable population with a myriad of health problems. Premature births are often accompanied by an underdeveloped immune system biased towards a Th2 phenotype and microbiota dysbiosis. Typically, a healthy gut microbiota interacts with the host, driving the proper maturation of the host immunity. However, factors like cesarean section, formula milk feeding, hospitalization in neonatal intensive care units (NICU), and routine antibiotic treatments compromise microbial colonization and increase the risk of developing related diseases. This, along with alterations in the innate immune system, could predispose the neonates to the development of respiratory diseases later in life. Currently, therapeutic strategies are mainly focused on restoring gut microbiota composition using probiotics and prebiotics. Understanding the interactions between the gut microbiota and the immature immune system in premature neonates could help to develop novel therapeutic strategies for treating or preventing gut-lung axis disorders.

Expiratory airflow limitation in adults born extremely preterm: A systematic review and meta-analysis

Extreme preterm (EP) birth, denoting delivery before the onset of the third trimester, interrupts intrauterine development and causes significant early-life pulmonary trauma, thereby posing a lifelong risk to respiratory health. We conducted a systematic review and meta-analysis to investigate adult lung function following EP birth (gestational age <28 weeks); comparing forced expiratory volume in first second (FEV1), forced vital capacity (FVC), and FEV1/FVC to reference values. Subgroup differences were explored based on timing of birth relative to surfactant use (1991) and bronchopulmonary dysplasia (BPD) status. Systematic searches were performed in Medline, EMBASE, Web of Science and Cochrane Central. Quality assessments were carried out using a modified Newcastle-Ottawa Scale for cohort studies. Sixteen studies encompassing 1036 EP-born adults were included, with 14 studies (n = 787) reporting data as %predicted, and 11 (n = 879) as z-score (not mutually exclusive). Overall mean [95 % confidence interval (CI)] %FEV1 was 85.30 (82.51; 88.09), %FVC was 94.33 (91.74; 96.91), and FEV1/FVC was 79.54 (77.71 to 81.38), all three with high heterogeneity. Overall mean (95 %CI) zFEV1 was -1.05 (-1.21; -0.90) and zFVC was. -0.45 (-0.59; -0.31), both with moderate heterogeneity. Subgroup analyses revealed no difference in FEV1 before versus after widespread use of surfactant, but more impairments after neonatal BPD. This meta-analysis revealed significant airflow limitation in EP-born adults, mostly explained by those with neonatal BPD. FEV1 was more reduced than FVC, and FEV1/FVC was at the lower limit of normal. Although at a group level, most adult EP-born individuals do not meet COPD criteria, these findings are concerning.

Body composition in adults born preterm with very low birth weight

BACKGROUND

Studies on body composition in preterm very low birth weight (VLBW < 1500 g) survivors are inconsistent and trajectories later in life unknown. We assessed body composition and its change from young to mid-adulthood in VLBW adults.

METHODS

We studied 137 VLBW adults and 158 term-born controls from two birth cohorts in Finland and Norway at mean age 36 years. Body composition was assessed by 8-polar bioelectrical impedance. We compared results with dual-energy x-ray absorptiometry measurements at 24 years.

RESULTS

In mid-adulthood, VLBW women and men were shorter than controls. Fat percentage (mean difference in women 1.1%; 95% CI, -1.5% to 3.5%, men 0.8%; -2.0% to 3.6%) and BMI were similar. VLBW women had 2.9 (0.9 to 4.8) kg and VLBW men 5.3 (2.7 to 8.1) kg lower lean body mass than controls, mostly attributable to shorter height. Between young and mid-adulthood, both groups gained fat and lean body mass (p for interaction VLBW x age>0.3).

CONCLUSION

Compared with term-born controls, VLBW adults had similar body fat percentage but lower lean body mass, largely explained by their shorter height. This could contribute to lower insulin sensitivity and muscular fitness previously found in VLBW survivors and predispose to functional limitations with increasing age.

IMPACT

In mid-adulthood, individuals born preterm with very low birth weight had similar body fat percentage but lower lean body mass than those born at term. This was largely explained by their shorter height. First study to report longitudinal assessments of body size and composition from young to mid-adulthood in very low birth weight adults. Lower lean body mass in very low birth weight adults could contribute to lower insulin sensitivity and muscular fitness and lead to earlier functional limitations with increasing age.

ERS International Congress 2023: highlights from the Basic and Translational Sciences Assembly

Early career members of Assembly 3 (Basic and Translational Sciences) of the European Respiratory Society (ERS) summarise the key messages discussed during six selected sessions that took place at the ERS International Congress 2023 in Milan, Italy. Aligned with the theme of the congress, the first session covered is "Micro- and macro-environments and respiratory health", which is followed by a summary of the "Scientific year in review" session. Next, recent advances in experimental methodologies and new technologies are discussed from the "Tissue modelling and remodelling" session and a summary provided of the translational science session, "What did you always want to know about omics analyses for clinical practice?", which was organised as part of the ERS Translational Science initiative's aims. The "Lost in translation: new insights into cell-to-cell crosstalk in lung disease" session highlighted how next-generation sequencing can be integrated with laboratory methods, and a final summary of studies is presented from the "From the transcriptome landscape to innovative preclinical models in lung diseases" session, which links the transcriptome landscape with innovative preclinical models. The wide range of topics covered in the selected sessions and the high quality of the research discussed demonstrate the strength of the basic and translational science being presented at the international respiratory conference organised by the ERS.

Young adult outcomes following premature birth: A Western Australian experience

BACKGROUND

Childhood outcomes following preterm birth are widely published, however long-term adult outcomes are less well described. We aimed to determine the quality of life and burden of co-morbidities experienced by preterm-born young adults in Western Australia.

METHODS

A retrospective observational study was conducted. Participants born at 23-33 weeks gestation cared for at King Edward Memorial Hospital during 1990 and 1991 were recruited from a historical birth cohort. Participants completed general, medical and reproductive health questionnaires. Results were compared with contemporaneous cohort data and/or population statistics.

RESULTS

Questionnaires were received from 73 young adults aged 28 to 30 years. The majority of respondents completed high school (94.5 %), were employed fulltime (74.0 %) and had close friends and family relationships. Almost all the participants considered their health to be good (94.0 %) and participated in light exercise (90.0 %). Increased hypertension, hypercholesterolaemia, asthma, neuropsychiatric conditions and visual impairment were reported. Depression Anxiety and Stress Scale (DASS-21) scoring identified increased mild anxiety. Increased consultation with healthcare workers and use of prescription medications were reported.

CONCLUSION

The group of preterm-born adults surveyed reported a good quality of life, supportive interpersonal relationships and they provided significant contributions to society. They did report increased medical and psychological conditions than the general population.

Evidence of abnormality in glutathione metabolism in the airways of preterm born children with a history of bronchopulmonary dysplasia

Preterm-born children are at risk of long-term pulmonary deficits, including those who developed bronchopulmonary dysplasia (BPD) in infancy, however the underlying mechanisms remain poorly understood. We characterised the exhaled breath condensate (EBC) metabolome from preterm-born children, both with and without BPD. Following spirometry, EBC from children aged 7-12 years, from the Respiratory Health Outcomes in Neonates study, were analysed using Time-of-Flight Mass Spectrometry. Metabolite Set Enrichment Analysis (MSEA) linked significantly altered metabolites to biological processes. Linear regression models examined relationships between metabolites of interest and participant demographics. EBC was analysed from 214 children, 144 were born preterm, including 34 with BPD. 235 metabolites were detected, with 38 above the detection limit in every sample. Alanine and pyroglutamic acid were significantly reduced in the BPD group when compared to preterm controls. MSEA demonstrated a reduction in glutathione metabolism. Reduced quantities of alanine, ornithine and urea in the BPD group were linked with alteration of the urea cycle. Linear regression revealed significant associations with BPD when other characteristics were considered, but not with current lung function parameters. In this exploratory study of the airway metabolome, preterm-born children with a history of BPD had changes consistent with reduced antioxidant mechanisms suggesting oxidative stress.

Impact of postnatal dexamethasone timing on preterm mortality and bronchopulmonary dysplasia: a propensity score analysis

BACKGROUND

Postnatal dexamethasone (PND) is used in high-risk preterm infants after the first week of life to facilitate extubation and prevent bronchopulmonary dysplasia (BPD) but the optimal treatment timing remains unclear. Our objective was to explore the association between the timing of PND commencement and mortality and respiratory outcomes.

METHODS

This was a retrospective National Neonatal Research Database study of 84 440 premature infants born <32 weeks gestational age from 2010 to 2020 in England and Wales. Propensity score weighting analysis was used to explore the impact of PND commenced at three time-points (2-3 weeks (PND2/3), 4-5 weeks (PND4/5) and after 5 weeks (PND6+) chronological age) on the primary composite outcome of death before neonatal discharge and/or severe BPD (defined as respiratory pressure support at 36 weeks) alongside other secondary respiratory outcomes.

RESULTS

3469 infants received PND. Compared with PND2/3, infants receiving PND6+ were more likely to die and/or develop severe BPD (OR 1.68, 95% CI 1.28-2.21), extubate at later postmenstrual age (mean difference 3.1 weeks, 95% CI 2.9-3.4 weeks), potentially require respiratory support at discharge (OR 1.34, 95% CI 1.06-1.70) but had lower mortality before discharge (OR 0.38, 95% CI 0.29-0.51). PND4/5 was not associated with severe BPD or discharge respiratory support.

CONCLUSIONS

PND treatment after 5 weeks of age was associated with worse respiratory outcomes although residual bias cannot be excluded. A definitive clinical trial to determine the optimal PND treatment window, based on early objective measures to identify high-risk infants, is needed.

Gestational age at birth and hospitalisations for infections among individuals aged 0-50 years in Norway: a longitudinal, register-based, cohort study

Background

Preterm birth is associated with increased risk of childhood infections. Whether this risk persists into adulthood is unknown and limited information is available on risk patterns across the full range of gestational ages.

Methods

In this longitudinal, register-based, cohort study, we linked individual-level data on all individuals born in Norway (January 01, 1967-December 31, 2016) to nationwide hospital data (January 01, 2008-December 31, 2017). Gestational age was categorised as 23-27, 28-31, 32-33, 34-36, 37-38, 39-41, and 42-44 completed weeks. The analyses were stratified by age at follow-up: 0-11 months and 1-5, 6-14, 15-29, and 30-50 years. The primary outcome was hospitalisation due to any infectious disease, with major infectious disease groups as secondary outcomes. Adjusted hospitalisation rate ratios (RRs) for any infection and infectious disease groups were estimated using negative binomial regression. Models were adjusted for year of birth, maternal age at birth, parity, and sex, and included an offset parameter adjusted for person-time at risk.

Findings

Among 2,695,830 individuals with 313,940 hospitalisations for infections, we found a pattern of higher hospitalisation risk in lower gestational age groups, which was the strongest in childhood but still evident in adulthood. Comparing those born very preterm (28-31) and late preterm (34-36) to full-term (39-41 weeks), RRs (95% confidence interval) for hospitalisation for any infectious disease at ages 1-5 were 3.3 (3.0-3.7) and 1.7 (1.6-1.8), respectively. At 30-50 years, the corresponding estimates were 1.4 (1.2-1.7) and 1.2 (1.1-1.3). The patterns were similar for the infectious disease groups, including bacterial and viral infections, respiratory tract infections (RTIs), and infections not attributable to RTIs.

Interpretation

Increasing risk of hospitalisations for infections in lower gestational age groups was most prominent in children but still evident in adolescents and adults. Possible mechanisms and groups that could benefit from vaccinations and other prevention strategies should be investigated.

Funding

St. Olav's University Hospital and Norwegian University of Science and Technology, Norwegian Research Council, Liaison Committee for education, research and innovation in Central Norway, European Commission, Academy of Finland, Sigrid Jusélius Foundation, Foundation for Pediatric Research, and Signe and Ane Gyllenberg Foundation.

Early-Life Nutrition in Preterm Infants and Risk of Respiratory Infections and Wheezing: A Scoping Review

INTRODUCTION

Preterm birth is a common early-life event that can lead to long-term consequences. The incidence of wheezing, asthma, and respiratory tract infections is higher in children born prematurely than in the general population. The purpose of this review was to synthesize the existing literature on the role of early-life nutrition in the later risk of respiratory morbidities.

METHODS

A scoping review of the literature was performed by searching three online databases. Inclusion criteria were: infants born <37 GWk, comparing human milk versus any other type of milk feeding formulation. Our primary outcomes were wheezing or asthma or respiratory tract infections after discharge. Two authors independently screened the results and extracted study characteristics using a predefined charting form.

RESULTS

Nine articles were included (eight cohort studies and one randomized trial). Four studies supported the protective effect of breastfeeding on wheezing or respiratory infections or both. Four studies did not confirm this association. One study confirmed the protective role of breastfeeding only on the subgroup of girls. There was a high heterogeneity among the included studies, in the type of milk feeding, outcomes, and age at follow-up.

CONCLUSIONS

The current evidence is conflicting. The high heterogeneity and methodological flaws could have influenced the results of the studies. Carefully designed studies are required to define the role of early-life nutrition among preterm infants on their long-term respiratory outcomes.