Background: Since the outbreak of coronavirus disease 2019 (COVID-19), many put their hopes in the rapid availability of effective immunizations. Human milk, containing antibodies against syndrome coronavirus 2 (SARS-CoV-2), may serve as means of protection through passive immunization. We aimed to determine the presence and pseudovirus neutralization capacity of SARS-CoV-2 specific IgA in human milk of mothers who recovered from COVID-19, and the effect of pasteurization on these antibodies. Methods: This prospective case control study included lactating mothers, recovered from (suspected) COVID-19 and healthy controls. Human milk and serum samples were collected. To assess the presence of SARS-CoV-2 antibodies we used multiple complementary assays, namely ELISA with the SARS-CoV-2 spike protein (specific for IgA and IgG), receptor binding domain (RBD) and nucleocapsid (N) protein for IgG in serum, and bridging ELISA with the SARS-CoV-2 RBD and N protein for specific Ig (IgG, IgM and IgA in human milk and serum). To assess the effect of pasteurization, human milk was exposed to Holder (HoP) and High Pressure Pasteurization (HPP). Results: Human milk contained abundant SARS-CoV-2 antibodies in 83% of the proven cases and in 67% of the suspected cases. Unpasteurized milk with and without these antibodies was found to be capable of neutralizing a pseudovirus of SARS-CoV-2 in (97% and 85% of the samples respectively). After pasteurization, total IgA antibody levels were affected by HoP, while SARS-CoV-2 specific antibody levels were affected by HPP. Pseudovirus neutralizing capacity of the human milk samples was only retained with the HPP approach. No correlation was observed between milk antibody levels and neutralization capacity. Conclusions: Human milk from recovered COVID-19-infected mothers contains SARS-CoV-2 specific antibodies which maintained neutralization capacity after HPP. All together this may represent a safe and effective immunization strategy after HPP.

To review systematically and assess the accuracy of prediction models for bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age. Searches were conducted in MEDLINE and EMBASE. Studies published between 1990 and 2022 were included if they developed or validated a prediction model for BPD or the combined outcome death/BPD at 36 weeks in the first 14 days of life in preterm infants. Data were extracted independently by two authors following the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Risk of bias was assessed using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). Sixty-five studies were reviewed, including 158 development and 108 externally validated models. Median c-statistic of 0.84 [range 0.43-1.00] was reported at model development, and 0.77 [range 0.41-0.97] at external validation. All models were rated at high risk of bias, due to limitations in the analysis part. Meta-analysis of the validated models revealed increased c-statistics after the first week of life for both the BPD and death/BPD outcome. Although BPD prediction models perform satisfactorily, they were all at high risk of bias. Methodological improvement and complete reporting are needed before they can be considered for use in clinical practice. Future research should aim to validate and update existing models.

Studies in preterm infants have shown an association between late-onset sepsis (LOS) and the development of bronchopulmonary dysplasia (BPD). It is unknown whether clinical or biochemical characteristics during sepsis modulate the risk for BPD. This single-center retrospective cohort study included all patients with a gestational age < 30 weeks, born between 2009 and 2015, in whom empiric antimicrobial treatment was initiated > 72 h after birth and continued for at least 5 days, independent on microbiological results. The association between clinical and biochemical characteristics of LOS and the development of BPD in survivors were assessed with multivariate logistic regression analysis adjusted for early-onset sepsis, small for gestational age, and gestational age. Of the 756 admitted infants, 256 infants (mean GA: 27.0 weeks; birthweight: 924 grams) had at least one LOS episode, of whom 79 (30.9%) developed BPD. Analyses showed that only the need for and duration of mechanical ventilation during LOS were independently associated with an increased risk for BPD (adjusted OR 2.62, 95% CI 1.38, 4.96, p value 0.003, and OR 1.004, 95% CI 1.00, 1.007, p value 0.045, respectively).Conclusion: During a LOS, the need for and duration of mechanical ventilation are independently associated with the risk of developing BPD in preterm infants. What is Known:• Premature infants diagnosed with a late-onset sepsis are at higher risk of developing bronchopulmonary dysplasia• This association is mainly shown in infants with a positive blood culture What is New:• This study investigates the clinical and biochemical characteristics of late-onset sepsis and the development of bronchopulmonary dysplasia• The need for mechanical ventilation and duration of mechanical ventilation during late-onset sepsis are associated with an increased risk of developing bronchopulmonary dysplasia.

Background: Chronic stress is often accompanied by alterations in the diurnal rhythm of hypothalamus–pituitary–adrenal activity. However, there are limited data on the diurnal rhythmicity of breast milk glucocorticoids (GCs) among women with psychological distress. We compared mothers who sought consultation at an expertise center for pregnant women with an increased risk of psychological distress with control mothers for GC diurnal rhythmicity in milk and saliva obtained at the same time. Methods: We included 19 mothers who sought consultation at the psychiatry–obstetric–pediatric (POP) outpatient clinic and 44 control mothers. One month postpartum, mothers collected on average eight paired milk and saliva samples during a 24 h period. GC levels were measured using liquid chromatography–tandem mass spectrometry. GC rhythmicity parameters were determined with specialized software. Results: For both milk and saliva, no group differences regarding GC rhythms were found. Milk cortisol area under the curve with respect to the ground was lower in the POP group than in the control group (p = 0.02). GC levels in human milk and saliva were highly correlated within each group (p < 0.001). Conclusion: Although there were no differences between groups in GC rhythmicity, the total amount of milk cortisol was lower in the POP group. Long-term follow-up is needed to address the impact of vertical transmission of breast milk GCs.

Background: Since the outbreak of COVID-19, many put their hopes in the rapid development of effective immunizations. For now patient isolation, physical distancing and good hygiene are the sole measures for prevention. Processed breast milk with antibodies against SaRS-CoV-2 may serve as additional protection. We aimed to determine the presence and neutralization capacity of antibodies against SaRS-CoV-2 in breastmilk of mothers who have recovered from COVID-19. Methods: This prospective case control study included lactating mothers, recovered from (suspected) COVID-19 and healthy controls. Serum and breastmilk was collected. To assess the presence of antibodies in breastmilk and serum, we used multiple complementary assays, namely ELISA with the SARS-CoV-2 spike protein, SARS-CoV-2 receptor binding domain (RBD) and with the SARS-CoV-2 nucleocapsid (N) protein for IgG and bridging ELISA with the SARS-CoV-2 RBD and N protein for total Ig. To assess the effect of pasteurization breastmilk was exposed to Holder Pasteurization and High Pressure Pasteurization. Results: Breastmilk contained antibodies against SARS-CoV-2 using any of the assays in 24 out of 29 (83%) proven cases, in six out of nine (67%) suspected cases and in none of the 13 controls. In vitro neutralization of SARS-CoV-2 clinical isolate virus strain was successful in a subset of serum (13%) and milk samples (26%). Although after pasteurization of the milk SARS-CoV-2 antibodies were detected with both methods of pasteurization, virus neutralizing capacity of those antibodies was only retained with the HPP approach. Conclusion: Breastmilk of mothers who recovered from COVID-19 contains significant amounts of IgA against SARS-CoV-2, both before and after pasteurization. Key Points: Question: Does breastmilk of mothers who have recovered from coronavirus disease 2019 (COVID-19) contain antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)? Findings: We provide multiple lines of evidence on the presence of a variety of antibodies against SARS-CoV-2, with no such antibodies present in the controls. These antibodies are capable of neutralizing a clinical isolate of SARS-CoV-2 in vitro . We furthermore show that high pressure pasteurization hardly affects antibody levels and efficacy. Meaning: Breastmilk, obtained from mothers who have recovered from COVID-19, may serve as a safe and widely applicable preventive strategy for vulnerable high risk populations

Background Systemic inflammation plays a key role in the development of bronchopulmonary dysplasia (BPD). Cortisol is known to dampen inflammation. However, adrenal function following preterm birth is characterized by insufficient cortisol levels for the degree of inflammation, and a relative abundancy of cortisol precursors. We investigated whether this pattern could contribute to the development of BPD in preterm infants born <30 weeks of gestation. Methods Cortisol, cortisone, 17-OH progesterone (17-OHP) and 11-deoxycortisol were measured in serum obtained at postnatal days 1, 3, 7, 14 and 28, using liquid-chromatography-tandem-mass-spectrometry. The presence of BPD was ascertained at 36 weeks postmenstrual age. Results Sixty-five infants were included for analysis, of whom 32 (49%) developed BPD. Preterm infants developing BPD, as compared to those without BPD, had higher levels of 17-OHP, 11-deoxycortisol and cortisone relative to cortisol in their first week of life, but not at birth or beyond day 7. Conclusion Preterm infants developing BPD had higher levels of cortisol precursors and cortisone relative to cortisol in their first week of life than infants without BPD. These findings suggest that BPD is preceded by an activated hypothalamus-pituitary-adrenal axis that could not meet the high cortisol demands, which may predispose to inflammation and BPD. Impact Relative adrenal insufficiency is common in the first weeks after preterm birth, resulting in insufficient cortisol production for the degree of inflammation and a relative abundance of cortisol precursors; Whether this pattern contributes to the development of bronchopulmonary dysplasia (BPD) is not fully elucidated, since most studies focused on cortisol levels; Preterm infants developing BPD had higher levels of cortisol precursors and cortisone relative to cortisol in the first week of life, suggestive of a hypothalamus-pituitary-adrenal-axis activation during BPD development which cannot meet the high cortisol demands in tissues; This glucocorticoid pattern is likely to dispose to inflammation and BPD.