Mothers' experiences of a new early collaborative intervention, the EACI, in the neonatal period: A qualitative study.

AIM: To explore mothers' experiences of the EArly Collaborative Intervention. BACKGROUND: Preterm birth puts a considerable emotional and psychological burden on parents and families. Parents to moderate and late premature infants have shorter stays at the neonatal intensive care unit and have described a need for support. The EArly Collaborative Intervention was developed to support parents with preterm infants born between gestational Weeks 30 to 36. In this study, mothers' experiences of the new intervention were explored. DESIGN: A qualitative design guided by a reflexive thematic analysis according to Braun and Clarke. Interviews were individually performed with 23 mothers experienced with the EArly Collaborative Intervention. Data were identified, analysed and reported using reflexive thematic analysis. The COREQ checklist was used preparing the manuscript. RESULTS: Two main overarching themes were constructed. The first theme, 'mothers' feelings evoked from the EArly Collaborative Intervention' describes the emotions raised by the intervention and how the intervention affected their parental role. Their awareness of the preterm baby's behaviour increased, and the intervention helped the parents to communicate around their baby's needs. The second theme, 'based on the preterm baby's behavior', describes experiences of the provision and the learning process about their preterm baby's needs and communication. The intervention was experienced as helpful both immediately and for future interaction with the baby. CONCLUSIONS: Mothers found the intervention to be supportive and encouraging. They came to look upon their baby as an individual, and the new knowledge on how to care and interact with their baby affected both their own and their baby's well-being. Furthermore, the intervention felt strengthening for their relationship with the other parent. RELEVANCE TO CLINICAL PRACTICE: The EArly Collaborative Intervention can support parents' abilities as well as their relation to their baby and may thereby contribute to infant development, cognition and well-being.

Extremely Preterm Infants Have Significant Alterations in Their Conventional T Cell Compartment during the First Weeks of Life.

Extremely preterm neonates are particularly susceptible to infections, likely because of severely impaired immune function. However, little is known on the composition of the T cell compartment in early life in this vulnerable population. We conducted a comprehensive phenotypic flow cytometry-based longitudinal analysis of the peripheral conventional T cell compartment of human extremely low gestational age neonates (ELGAN) with extremely low birth weight (ELBW; <1000 g) participating in a randomized placebo-controlled study of probiotic supplementation. PBMCs from ELGAN/ELBW neonates were collected at day 14, day 28, and postmenstrual week 36. Comparisons were made with full-term 14-d-old neonates. Total CD4+ and CD8+ T cell frequencies were markedly lower in the preterm neonates. The reduction was more pronounced among the CD8+ population, resulting in an increased CD4/CD8 ratio. The preterm infants were also more Th2 skewed than the full-term infants. Although the frequency of regulatory T cells seemed normal in the ELGAN/ELBW preterm neonates, their expression of the homing receptors α4ß7, CCR4, and CCR9 was altered. Notably, ELGAN/ELBW infants developing necrotizing enterocolitis before day 14 had higher expression of CCR9 in CD4+T cells at day 14. Chorioamnionitis clearly associated with reduced T regulatory cell frequencies and functional characteristics within the preterm group. Finally, probiotic supplementation with Lactobacillus reuteri did not impose any phenotypic changes of the conventional T cell compartment. In conclusion, notable immaturities of the T cell compartment in ELGAN/ELBW neonates may at least partially explain their increased susceptibility to severe immune-mediated morbidities.

Characterization of the γδ T-cell compartment during infancy reveals clear differences between the early neonatal period and 2 years of age.

γδ T cells are unconventional T cells that function on the border of innate and adaptive immunity. They are suggested to play important roles in neonatal and infant immunity, although their phenotype and function are not fully characterized in early childhood. We aimed to investigate γδ T cells in relation to age, prematurity and cytomegalovirus (CMV) infection. Therefore, we used flow cytometry to characterize the γδ T-cell compartment in cord blood and peripheral blood cells from 14-day-, 2-year- and 5-year-old children, as well as in peripheral blood samples collected at several time points during the first months of life from extremely premature neonates. γδ T cells were phenotypically similar at 2 and 5 years of age, whereas cord blood was divergent and showed close proximity to γδ T cells from 14-day-old neonates. Interestingly, 2-year-old children and adults showed comparable Vδ2+ γδ T-cell functionality toward both microbial and polyclonal stimulations. Importantly, extreme preterm birth compromised the frequencies of Vδ1+ cells and affected the functionality of Vδ2+ γδ T cells shortly after birth. In addition, CMV infection was associated with terminal differentiation of the Vδ1+ compartment at 2 years of age. Our results show an adult-like functionality of the γδ T-cell compartment already at 2 years of age. In addition, we demonstrate an altered γδ T-cell phenotype early after birth in extremely premature neonates, something which could possible contribute to the enhanced risk for infections in this vulnerable group of children.

Allergy development is associated with consumption of breastmilk with a reduced microbial richness in the first month of life.

BACKGROUND: Early colonization with a diverse microbiota seems to play a crucial role for appropriate immune maturation during childhood. Breastmilk microbiota is one important source of microbes for the infant, transferred together with maternal IgA antibodies. We previously observed that allergy development during childhood was associated with aberrant IgA responses to the gut microbiota already at 1 month of age, when the IgA antibodies are predominantly maternally derived in breastfed infants. OBJECTIVE: To determine the microbial composition and IgA-coated bacteria in breastmilk in relation to allergy development in children participating in an intervention trial with pre- and post-natal Lactobacillus reuteri supplementation. METHODS: A combination of flow cytometric cell sorting and 16S rRNA gene sequencing was used to characterize the bacterial recognition patterns by IgA in breastmilk samples collected one month post-partum from 40 mothers whose children did or did not develop allergic and asthmatic symptoms during the first 7 years of age. RESULTS: The milk fed to children developing allergic manifestations had significantly lower bacterial richness, when compared to the milk given to children that remained healthy. Probiotic treatment influenced the breastmilk microbiota composition. However, the proportions of IgA-coated bacteria, the total bacterial load and the patterns of IgA-coating were similar in breastmilk between mothers of healthy children and those developing allergies. CONCLUSION: Consumption of breastmilk with a reduced microbial richness in the first month of life may play an important role in allergy development during childhood.

Pre- and postnatal Lactobacillus reuteri treatment alters DNA methylation of infant T helper cells.

BACKGROUND: Perinatal childhood exposures, including probiotic supplementation, may affect epigenetic modifications and impact on immune maturation and allergy development. The aim of this study was to assess the effects of pre- and postnatal Lactobacillus reuteri supplementation on DNA methylation in relation to immune maturation and allergy development. METHODS: DNA methylation patterns were investigated for allergy-related T helper subsets using a locus-specific method and at a genome-wide scale using the Illumina 450K array. From a randomised, double-blind, placebo-controlled allergy prevention trial with pre- and postnatal probiotic supplementation, CD4+ T helper cells were obtained at birth (from cord blood), and 12 and 24 months of age (total (placebo/probiotics); locus-specific method: CB = 32 (17/15), 12 months = 24 (9/15), 24 months = 35 (15/20); Illumina: CB = 19 (10/9), 12 months = 10 (6/4), 24 months = 19(11/8)). RESULTS: Comparing probiotics to placebo, the greatest genome-wide differential DNA methylation was observed at birth, where the majority of sites were hypomethylated, indicating transcriptional accessibility in the probiotic group. Bioinformatic analyses, including network analyses, revealed a module containing 91 genes, enriched for immune-related pathways such as chemotaxis, PI3K-Akt, MAPK and TGF-ß signalling. A majority of the module genes were associated with atopic manifestations (OR = 1.43, P = 2.4 × 10-6 ), and a classifier built on this model could predict allergy development (AUC = 0.78, P = 3.0 × 10e-3 ). Pathways such as IFN-γ signalling and T-cell activation were more hypermethylated at birth compared with later in life in both intervention groups over time, in line with DNA methylation patterns in the IFNG locus obtained by the locus-specific methodology. CONCLUSION: Maternal L. reuteri supplementation during pregnancy alters DNA methylation patterns in CD4+ T cells towards enhanced immune activation at birth, which may affect immune maturation and allergy development.

Probiotics promoted head growth in extremely low birthweight infants in a double-blind placebo-controlled trial.

AIM: This study evaluated if oral supplementation with the probiotic bacterium Lactobacillus reuteri DSM 17938 improved enteral feeding tolerance and growth rates in extremely low birthweight (ELBW) infants. METHOD: A randomised, double-blind, placebo-controlled trial comprising 134 ELBW (<1000 g) infants born before gestational week 28 + 0. Daily supplementation of L. reuteri (1.25 × 108 bacteria/day) or placebo started within 3 days and continued until gestational week 36 + 0. Primary outcome was feeding tolerance and secondary outcome growth rate calculated as z-score development. RESULTS: Feeding tolerance was similar in the probiotic and placebo group. Time to full enteral feeds was 15 days in both groups. The z-score of the head circumference decreased in both groups from birth to day 28 of life, but it decreased less in the L. reuteri group compared to the placebo group: -1.2 SD (95% CI: -1.4 to -1.0) versus -1.7 SD (95% CI: -2.0 to -1.5; p = 0.001). Other growth parameters were similar in the study groups. CONCLUSION: Lactobacillus reuteri did not reduce time to reach full enteral feeds in ELBW infants. The L. reuteri supplemented infants, however, had a better growth rate of the head during the first month of life.

Association Between Year of Birth and 1-Year Survival Among Extremely Preterm Infants in Sweden During 2004-2007 and 2014-2016.

Importance: Since 2004-2007, national guidelines and recommendations have been developed for the management of extremely preterm births in Sweden. If and how more uniform management has affected infant survival is unknown. Objective: To compare survival of extremely preterm infants born during 2004-2007 with survival of infants born during 2014-2016. Design, Setting and Participants: All births at 22-26 weeks' gestational age (n = 2205) between April 1, 2004, and March 31, 2007, and between January 1, 2014, and December 31, 2016, in Sweden were studied. Prospective data collection was used during 2004-2007. Data were obtained from the Swedish pregnancy, medical birth, and neonatal quality registries during 2014-2016. Exposures: Delivery at 22-26 weeks' gestational age. Main Outcomes and Measures: The primary outcome was infant survival to the age of 1 year. The secondary outcome was 1-year survival among live-born infants who did not have any major neonatal morbidity (specifically, without intraventricular hemorrhage grade 3-4, cystic periventricular leukomalacia, necrotizing enterocolitis, retinopathy of prematurity stage 3-5, or severe bronchopulmonary dysplasia). Results: During 2004-2007, 1009 births (3.3/1000 of all births) occurred at 22-26 weeks' gestational age compared with 1196 births (3.4/1000 of all births) during 2014-2016 (P = .61). One-year survival among live-born infants at 22-26 weeks' gestational age was significantly lower during 2004-2007 (497 of 705 infants [70%]) than during 2014-2016 (711 of 923 infants [77%]) (difference, -7% [95% CI, -11% to -2.2%], P = .003). One-year survival among live-born infants at 22-26 weeks' gestational age and without any major neonatal morbidity was significantly lower during 2004-2007 (226 of 705 infants [32%]) than during 2014-2016 (355 of 923 infants [38%]) (difference, -6% [95% CI, -11% to -1.7%], P = .008). Conclusions and Relevance: Among live births at 22-26 weeks' gestational age in Sweden, 1-year survival improved between 2004-2007 and 2014-2016.

Hyperglycemia in Extremely Preterm Infants-Insulin Treatment, Mortality and Nutrient Intakes.

OBJECTIVE: To explore the prevalence of hyperglycemia and the associations between nutritional intakes, hyperglycemia, insulin treatment, and mortality in extremely preterm infants. STUDY DESIGN: Prospectively collected data from the Extremely Preterm Infants in Sweden Study (EXPRESS) was used in this study and included 580 infants born <27 gestational weeks during 2004-2007. Available glucose measurements (n = 9850) as well as insulin treatment and nutritional data were obtained retrospectively from hospital records for the first 28 postnatal days as well as 28- and 70-day mortality data. RESULTS: Daily prevalence of hyperglycemia >180 mg/dL (10 mmol/L) of up to 30% was observed during the first 2 postnatal weeks, followed by a slow decrease in its occurrence thereafter. Generalized additive model analysis showed that increasing parenteral carbohydrate supply with 1 g/kg/day was associated with a 1.6% increase in glucose concentration (P < .001). Hyperglycemia was associated with more than double the 28-day mortality risk (P < .01). In a logistic regression model, insulin treatment was associated with lower 28- and 70-day mortality when given to infants with hyperglycemia irrespective of the duration of the hyperglycemic episode (P < .05). CONCLUSIONS: Hyperglycemia is common in extremely preterm infants throughout the first postnatal month. Glucose infusions seem to have only a minimal impact on glucose concentrations. In the EXPRESS cohort, insulin treatment was associated with lower mortality in infants with hyperglycemia. Current practices of hyperglycemia treatment in extremely preterm infants should be reevaluated and assessed in randomized controlled clinical trials.

Aberrant IgA responses to the gut microbiota during infancy precede asthma and allergy development.

BACKGROUND: Although a reduced gut microbiota diversity and low mucosal total IgA levels in infancy have been associated with allergy development, IgA responses to the gut microbiota have not yet been studied. OBJECTIVE: We sought to determine the proportions of IgA coating together with the characterization of the dominant bacteria, bound to IgA or not, in infant stool samples in relation to allergy development. METHODS: A combination of flow cytometric cell sorting and deep sequencing of the 16S rDNA gene was used to characterize the bacterial recognition patterns by IgA in stool samples collected at 1 and 12 months of age from children staying healthy or having allergic symptoms up to 7 years of age. RESULTS: The children with allergic manifestations, particularly asthma, during childhood had a lower proportion of IgA bound to fecal bacteria at 12 months of age compared with healthy children. These alterations cannot be attributed to differences in IgA levels or bacterial load between the 2 groups. Moreover, the bacterial targets of early IgA responses (including coating of the Bacteroides genus), as well as IgA recognition patterns, differed between healthy children and children with allergic manifestations. Altered IgA recognition patterns in children with allergy were observed already at 1 month of age, when the IgA antibodies are predominantly maternally derived in breast-fed children. CONCLUSION: An aberrant IgA responsiveness to the gut microbiota during infancy precedes asthma and allergy development, possibly indicating an impaired mucosal barrier function in allergic children.

Human seroreactivity to gut microbiota antigens.

BACKGROUND: Although immune responses directed against antigens from the intestinal microbiota are observed in certain diseases, the normal human adaptive immune response to intestinal microbiota is poorly defined. OBJECTIVE: Our goal was to assess the adaptive immune response to the intestinal microbiota present in 143 healthy adults and compare this response with the response observed in 52 children and their mothers at risk of having allergic disease. METHODS: Human serum was collected from adults and children followed from birth to 7 years of age, and the serum IgG response to a panel of intestinal microbiota antigens was assessed by using a novel protein microarray. RESULTS: Nearly every subject tested, regardless of health status, had serum IgG that recognized a common set of antigens. Seroreactivity to the panel of antigens was significantly lower in atopic adults. Healthy infants expressed the highest level of IgG seroreactivity to intestinal microbiota antigens. This adaptive response developed between 6 and 12 months of age and peaked around 2 years of age. Low IgG responses to certain clusters of microbiota antigens during infancy were associated with allergy development during childhood. CONCLUSIONS: There is an observed perturbation of the adaptive response to antigens from the microbiota in allergic subjects. These perturbations are observable even in childhood, suggesting that optimal stimulation of the adaptive immune system by the microbiota might be needed to prevent certain immune-mediated diseases.

Gut microbiota and allergy: the importance of the pregnancy period.

Limited microbial exposure is suggested to underlie the increase of allergic diseases in affluent countries, and bacterial diversity seems to be more important than specific bacteria taxa. Prospective studies indicate that the gut microbiota composition during the first months of life influences allergy development, and support the theory that factors influencing the early maturation of the immune system might be important for subsequent allergic disease. However, recent research indicates that microbial exposure during pregnancy may be even more important for the preventative effects against allergic disease. This review gives a background of the epidemiology, immunology, and microbiology literature in this field. It focuses on possible underlying mechanisms such as immune-regulated epigenetic imprinting and bacterial translocation during pregnancy, potentially providing the offspring with a pioneer microbiome. We suggest that a possible reason for the initial exposure of bacterial molecular patterns to the fetus in utero is to prime the immune system and/or the epithelium to respond appropriately to pathogens and commensals after birth.

Decreased gut microbiota diversity, delayed Bacteroidetes colonisation and reduced Th1 responses in infants delivered by caesarean section.

OBJECTIVE: The early intestinal microbiota exerts important stimuli for immune development, and a reduced microbial exposure as well as caesarean section (CS) has been associated with the development of allergic disease. Here we address how microbiota development in infants is affected by mode of delivery, and relate differences in colonisation patterns to the maturation of a balanced Th1/Th2 immune response. DESIGN: The postnatal intestinal colonisation pattern was investigated in 24 infants, born vaginally (15) or by CS (nine). The intestinal microbiota were characterised using pyrosequencing of 16S rRNA genes at 1 week and 1, 3, 6, 12 and 24 months after birth. Venous blood levels of Th1- and Th2-associated chemokines were measured at 6, 12 and 24 months. RESULTS: Infants born through CS had lower total microbiota diversity during the first 2 years of life. CS delivered infants also had a lower abundance and diversity of the Bacteroidetes phylum and were less often colonised with the Bacteroidetes phylum. Infants born through CS had significantly lower levels of the Th1-associated chemokines CXCL10 and CXCL11 in blood. CONCLUSIONS: CS was associated with a lower total microbial diversity, delayed colonisation of the Bacteroidetes phylum and reduced Th1 responses during the first 2 years of life.

Effects of extremely preterm birth on cytokine and chemokine responses induced by T-cell activation during infancy.

Objectives: Extremely preterm (EPT; gestational week < 28 + 0, < 1000 g) neonates are vulnerable to infections and necrotising enterocolitis, important contributors to mortality and morbidity. However, knowledge regarding their immune maturation remains limited. We here investigated the longitudinal development of functional T-cell capacity in EPT infants. Methods: Peripheral blood mononuclear cells were isolated at 14th and 28th day (D) and at gestational week 36 + 0 (Gw36) from EPT infants, participated in a randomised, double-blind, placebo-controlled study of Lactobacillus reuteri DSM 17938 probiotic supplementation. Blood collected from 25 full-term (FT) infants at D14 was used as control. The secretion of immune mediators was determined through comprehensive Luminex panels after stimulation with human T-cell activator CD3/CD28 beads. Results: The levels of many mediators were low in EPT infants at D14, whereas the secretion of several chemokines was higher in EPT than in FT infants. Furthermore, Th2:Th1 cytokine ratios were higher in EPT than in FT infants. Progressively elevated secretion of, for example, IFN-γ, TNF and IL-17A in EPT infants was observed from D14 to D28 and then at Gw36. Elevated levels were observed for many proinflammatory mediators at D28. Probiotic supplementation or perinatal factors (e.g. clinical chorioamnionitis, preeclampsia and delivery mode) did not influence the cytokine and chemokine responses. Conclusions: Immune mediators induced by T-cell activation in EPT infants were mainly reduced at D14 and Th2 skewed compared to those in FT infants, but mostly recovered at Gw36, indicating immune maturation. Increased proinflammatory responses at D28 may be related to the heightened risk of severe immune-associated complications seen in EPT infants.

Effect of human milk-based fortification in extremely preterm infants fed exclusively with breast milk: a randomised controlled trial.

Background: Mortality and severe morbidity remain high in extremely preterm infants. Human milk-based nutrient fortifiers may prevent serious complications and death. We aimed to investigate whether supplementation with human milk-based fortifier (HMBF), as compared to bovine milk-based fortifier (BMBF), reduced the incidence of the composite outcome of necrotising enterocolitis (NEC), sepsis, and mortality in extremely preterm infants exclusively fed human milk. Methods: In this multicentre, randomised controlled trial at 24 neonatal units in Sweden, extremely preterm infants born between gestational week 22 + 0 and 27 + 6 fed exclusively human breast milk (mother's own and/or donor milk), were randomly assigned (1:1) to receive targeted fortification with either HMBF or BMBF. Randomisation was conducted before the enteral feeds reached 100 mL/kg/day, and was stratified by enrolment site, gestational age, singleton/twin, and sex. The allocation was concealed before inclusion, but after randomisation the study was not blinded for the clinical staff. For the NEC diagnosis, the study group was masked to an independent radiologist, and the final assessment of NEC and culture-proven sepsis was done by a blinded consensus panel review. The primary outcome was the composite of NEC stage II-III, culture-proven sepsis, and mortality from inclusion to discharge, no longer than postmenstrual week 44 + 0, in the intention-to-treat population (ClinicalTrials.gov, NCT03797157). Findings: Between February 21st, 2019, and May 21st, 2021, 229 neonates were randomly assigned (115 HMBF, 114 BMBF). After exclusion of one infant due to parents' withdrawal of consent, 228 infants were included in the intention-to-treat analysis. Of the 115 infants assigned to HMBF, 41 (35.7%) fulfilled the criteria of either NEC, sepsis, or death, compared with 39 (34.5%) of 113 infants assigned to BMBF (OR 1.05, 95% CI 0.61-1.81, p = 0.86). Adverse events did not differ significantly between groups. Interpretation: Supplementation with HMBF, as compared with BMBF, did not reduce the incidence of the composite outcome of NEC, sepsis, or death. Our results do not support routine supplementation with HMBF as a nutritional strategy to prevent NEC, sepsis, or death in extremely preterm infants exclusively fed human milk. Funding: ALF grant, Prolacta Bioscience, Swedish Research Council, and Research Council for Southeast Sweden.

No effect of probiotics on respiratory allergies: a seven-year follow-up of a randomized controlled trial in infancy.

BACKGROUND: Supplementation with the probiotic Lactobacillus reuteri reduced the incidence of IgE-associated allergic disease in infancy. This treatment might therefore also reduce the risk of asthma and allergic rhinoconjunctivitis in school age. OBJECTIVE: To evaluate whether perinatal and infant supplementation with L. reuteri reduced the prevalence of respiratory allergic disease in school age and to explore whether this supplementation was associated with any long-term side effects. METHODS: A randomized, placebo-controlled trial with oral supplementation with L. reuteri ATCC 55730 (1 × 10(8) CFU) during the last month of gestation and through the first year of life comprising 232 families with allergic disease, of whom 184 completed a 7-yr follow-up. The primary outcomes at 7 yr of age were allergic disease and skin prick test reactivity (ClinicalTrials.gov ID NCT01285830). RESULTS: The prevalence of asthma (15% in the probiotic vs. 16% in placebo group), allergic rhinoconjunctivitis (27% vs. 20%), eczema (21% vs. 19%) and skin prick test reactivity (29% vs. 26%) was similar in the probiotic and placebo group. Growth indices and gastrointestinal symptoms were similar in the two groups. No severe adverse events were reported. CONCLUSION: The effect of L. reuteri on sensitization and IgE-associated eczema in infancy did not lead to a lower prevalence of respiratory allergic disease in school age. Thus, the effect of L. reuteri on the immune system seems to be transient. Administration of L. reuteri during the last weeks of gestation and in infancy was not associated with any long-term side effects.

Low diversity of the gut microbiota in infants with atopic eczema.

BACKGROUND: It is debated whether a low total diversity of the gut microbiota in early childhood is more important than an altered prevalence of particular bacterial species for the increasing incidence of allergic disease. The advent of powerful, cultivation-free molecular methods makes it possible to characterize the total microbiome down to the genus level in large cohorts. OBJECTIVE: We sought to assess microbial diversity and characterize the dominant bacteria in stool during the first year of life in relation to atopic eczema development. METHODS: Microbial diversity and composition were analyzed with barcoded 16S rDNA 454-pyrosequencing in stool samples at 1 week, 1 month, and 12 months of age in 20 infants with IgE-associated eczema and 20 infants without any allergic manifestation until 2 years of age (ClinicalTrials.gov ID NCT01285830). RESULTS: Infants with IgE-associated eczema had a lower diversity of the total microbiota at 1 month (P = .004) and a lower diversity of the bacterial phylum Bacteroidetes and the genus Bacteroides at 1 month (P = .02 and P = .01) and the phylum Proteobacteria at 12 months of age (P = .02). The microbiota was less uniform at 1 month than at 12 months of age, with a high interindividual variability. At 12 months, when the microbiota had stabilized, Proteobacteria, comprising gram-negative organisms, were more abundant in infants without allergic manifestation (Empirical Analysis of Digital Gene Expression in R [edgeR] test: P = .008, q = 0.02). CONCLUSION: Low intestinal microbial diversity during the first month of life was associated with subsequent atopic eczema.

One-year survival and outcomes of infants born at 22 and 23 weeks of gestation in Sweden 2004-2007, 2014-2016 and 2017-2019.

OBJECTIVE: To explore associations between perinatal activity and survival in infants born at 22 and 23 weeks of gestation in Sweden. DESIGN/SETTING: Data on all births at 22 and 23 weeks' gestational age (GA) were prospectively collected in 2004-2007 (T1) or obtained from national registers in 2014-2016 (T2) and 2017-2019 (T3). Infants were assigned perinatal activity scores based on 3 key obstetric and 4 neonatal interventions. MAIN OUTCOME: One-year survival and survival without major neonatal morbidities (MNM): intraventricular haemorrhage grade 3-4, cystic periventricular leucomalacia, surgical necrotising enterocolitis, retinopathy of prematurity stage 3-5 or severe bronchopulmonary dysplasia. The association of GA-specific perinatal activity score and 1-year survival was also determined. RESULTS: 977 infants (567 live births and 410 stillbirths) were included: 323 born in T1, 347 in T2 and 307 in T3. Among live-born infants, survival at 22 weeks was 5/49 (10%) in T1 and rose significantly to 29/74 (39%) in T2 and 31/80 (39%) in T3. Survival was not significantly different between epochs at 23 weeks (53%, 61% and 67%). Among survivors, the proportions without MNM in T1, T2 and T3 were 20%, 17% and 19% for 22 weeks and 17%, 25% and 25% for 23 weeks' infants (p>0.05 for all comparisons). Each 5-point increment in GA-specific perinatal activity score increased the odds for survival in first 12 hours of life (adjusted OR (aOR) 1.4; 95% CI 1.3 to 1.6) in addition to 1-year survival (aOR 1.2; 95% CI 1.1 to 1.3), and among live-born infants it was associated with increased survival without MNM (aOR 1.3; 95% CI 1.1 to 1.4). CONCLUSION: Increased perinatal activity was associated with reduced mortality and increased chances of survival without MNM in infants born at 22 and 23 weeks of GA.

Factors associated with the increased incidence of necrotising enterocolitis in extremely preterm infants in Sweden between two population-based national cohorts (2004-2007 vs 2014-2016).

OBJECTIVE: To investigate potential risk factors behind the increased incidence of necrotising enterocolitis (NEC) in Swedish extremely preterm infants. DESIGN: Registry data from two population-based national cohorts were studied. NEC diagnoses (Bell stage ≥II) were validated against hospital records. PATIENTS: All liveborn infants <27 weeks of gestation 2004-2007 (n=704) and 2014-2016 (n=895) in Sweden. MAIN OUTCOME MEASURES: NEC incidence. RESULTS: The validation process resulted in a 28% reduction of NEC cases but still confirmed a higher NEC incidence in the later epoch compared with the earlier (73/895 (8.2%) vs 27/704 (3.8%), p=0.001), while the composite of NEC or death was lower (244/895 (27.3%) vs 229/704 (32.5%), p=0.022). In a multivariable Cox regression model, censored for mortality, there was no significant difference in early NEC (0-7 days of life) between epochs (HR=0.9 (95% CI 0.5 to 1.9), p=0.9), but being born in the later epoch remained an independent risk factor for late NEC (>7 days) (HR=2.7 (95% CI 1.5 to 5.0), p=0.001). In propensity score analysis, a significant epoch difference in NEC incidence (12% vs 2.8%, p<0.001) was observed only in the tertile of infants at highest risk of NEC, where the 28-day mortality was lower in the later epoch (35% vs 50%, p=0.001). More NEC cases were diagnosed with intramural gas in the later epoch (33/73 (45.2%) vs 6/26 (23.1%), p=0.047). CONCLUSIONS: The increase in NEC incidence between epochs was limited to cases occurring after 7 days of life and was partly explained by increased survival in the most extremely preterm infants. Misclassification of NEC is common.