Postnatal serum IGF-1 levels associate with brain volumes at term in extremely preterm infants.

BACKGROUND: Growth factors important for normal brain development are low in preterm infants. This study investigated the link between growth factors and preterm brain volumes at term. MATERIAL/METHODS: Infants born <28 weeks gestational age (GA) were included. Endogenous levels of insulin-like growth factor (IGF)-1, brain-derived growth factor, vascular endothelial growth factor, and platelet-derived growth factor (expressed as area under the curve [AUC] for serum samples from postnatal days 1, 7, 14, and 28) were utilized in a multivariable linear regression model. Brain volumes were determined by magnetic resonance imaging (MRI) at term equivalent age. RESULTS: In total, 49 infants (median [range] GA 25.4 [22.9-27.9] weeks) were included following MRI segmentation quality assessment and AUC calculation. IGF-1 levels were independently positively associated with the total brain (p < 0.001, ß = 0.90), white matter (p = 0.007, ß = 0.33), cortical gray matter (p = 0.002, ß = 0.43), deep gray matter (p = 0.008, ß = 0.05), and cerebellar (p = 0.006, ß = 0.08) volume adjusted for GA at birth and postmenstrual age at MRI. No associations were seen for other growth factors. CONCLUSIONS: Endogenous exposure to IGF-1 during the first 4 weeks of life was associated with total and regional brain volumes at term. Optimizing levels of IGF-1 might improve brain growth in extremely preterm infants. IMPACT: High serum levels of insulin-like growth factor (IGF)-1 during the first month of life were independently associated with increased total brain volume, white matter, gray matter, and cerebellar volume at term equivalent age in extremely preterm infants. IGF-1 is a critical regulator of neurodevelopment and postnatal levels are low in preterm infants. The effects of IGF-1 levels on brain development in extremely preterm infants are not fully understood. Optimizing levels of IGF-1 may benefit early brain growth in extremely preterm infants. The effects of systemically administered IGF-1/IGFBP3 in extremely preterm infants are now being investigated in a randomized controlled trial (Clinicaltrials.gov: NCT03253263).

Insulin-Like Growth Factor 1 in the Preterm Rabbit Pup: Characterization of Cerebrovascular Maturation following Administration of Recombinant Human Insulin-Like Growth Factor 1/Insulin-Like Growth Factor 1-Binding Protein 3.

Following preterm birth, serum levels of insulin-like growth factor 1 (IGF-1) decrease compared to corresponding in utero levels. A recent clinical trial indicated that supplementation with recombinant human (rh) IGF-1/rhIGF-binding protein 3 (rhIGF-1/rhIGFBP-3) prevents severe intraventricular hemorrhage (IVH) in extremely preterm infants. In a preterm rabbit pup model, we characterized endogenous serum and hepatic IGF-1, along with brain distribution of IGF-1 and IGF-1 receptor (IGF1R). We then evaluated the effects of rhIGF-1/rhIGFBP-3 on gene expression of regulators of cerebrovascular maturation and structure. Similar to preterm infants, serum IGF-1 concentrations decreased rapidly after preterm birth in the rabbit pup. Administration of rhIGF-1/rhIGFBP-3 restored in utero serum levels but was rapidly eliminated. Immunolabeled IGF1R was widely distributed in multiple brain regions, displaying an abundant density in the choroid plexus and sub-ependymal germinal zones. Increased IGF-1 immunoreactivity, distributed as IGF1R, was detected 4 h after rhIGF-1/rhIGFBP-3 administration. The rhIGF-1/rhIGFBP-3 treatment led to upregulation of choroid plexus genes involved in vascular maturation and structure, with corresponding protein translation for most of these genes. The preterm rabbit pup model is well suited for evaluation of IGF-1-based prevention of IVH. Administration of rhIGF-1/rhIGFBP-3 affects cerebrovascular maturation, suggesting a role for it in preventing preterm IVH.

Serum docosahexaenoic acid levels are associated with brain volumes in extremely preterm born infants.

BACKGROUND: Docosahexaenoic acid (DHA) and arachidonic acid (AA) are important for fetal brain growth and development. Our aim was to evaluate the association between serum DHA and AA levels and brain volumes in extremely preterm infants. METHODS: Infants born at <28 weeks gestational age in 2013-2015, a cohort derived from a randomized controlled trial comparing two types of parenteral lipid emulsions, were included (n = 90). Serum DHA and AA levels were measured at postnatal days 1, 7, 14, and 28, and the area under the curve was calculated. Magnetic resonance (MR) imaging was performed at term-equivalent age (n = 66), and volumes of six brain regions were automatically generated. RESULTS: After MR image quality assessment and area under the curve calculation, 48 infants were included (gestational age mean [SD] 25.5 [1.4] weeks). DHA levels were positively associated with total brain (B = 7.966, p = 0.012), cortical gray matter (B = 3.653, p = 0.036), deep gray matter (B = 0.439, p = 0.014), cerebellar (B = 0.932, p = 0.003), and white matter volume (B = 3.373, p = 0.022). AA levels showed no association with brain volumes. CONCLUSIONS: Serum DHA levels during the first 28 postnatal days were positively associated with volumes of several brain structures in extremely preterm infants at term-equivalent age. IMPACT: Higher serum levels of DHA in the first 28 postnatal days are positively associated with brain volumes at term-equivalent age in extremely preterm born infants. Especially the most immature infants suffer from low DHA levels in the first 28 postnatal days, with little increase over time. Future research is needed to explore whether postnatal fatty acid supplementation can improve brain development and may serve as a nutritional preventive and therapeutic treatment option in extremely preterm infants.

Neonatal clinical blood sampling led to major blood loss and was associated with bronchopulmonary dysplasia.

AIM: Studies indicate that reduced foetal haemoglobin levels are related to increased neonatal morbidity rates. This study investigated the relationships between sampling-related blood loss and adult blood transfusions administered during postnatal days 1-14 and the development of severe neonatal morbidities in extremely preterm infants born before 28 weeks of gestation. METHODS: The medical files of 149 extremely preterm infants born at two university hospitals in Sweden from 2013 to 2018 were investigated. RESULTS: Blood sampling resulted in a 58% depletion of the endogenous blood volume postnatal days 1-14 (median 40.4 mL/kg, interquartile range 23.9-53.3 mL/kg) and correlated with the adult erythrocyte transfusion volume (rS  = 0.870, P < .001). Sampling-related blood loss on postnatal days 1-7, adjusted for gestational age at birth and birth weight standard deviation score, was associated with the development of bronchopulmonary dysplasia (BPD) (odds ratio by a 10-unit increase 2.4, 95% confidence interval 1.1-5.4) (P = .03). No associations were found between blood sampling and intraventricular haemorrhage or necrotising enterocolitis in the full statistical model. The largest proportion of sampling-related blood was used for blood gas analyses (48.7%). CONCLUSION: Diagnostic blood sampling led to major endogenous blood loss replaced with adult blood components and was associated with the development of BPD.

Low fraction of fetal haemoglobin is associated with retinopathy of prematurity in the very preterm infant.

BACKGROUND: Blood loss and adult blood transfusions are common during the neonatal period in preterm infants. The objective of the study was to clarify if degree of loss of fetal haemoglobin (HbF) was associated with later retinopathy of prematurity (ROP). METHODS: Retrospective observational cohort study. In total, 452 infants born <30 gestational weeks at a tertiary level neonatal intensive care unit in Sweden in 2009-2015 were included, 385 of whom had final ROP outcome. Mean fractions of HbF (%) during the first postnatal week were calculated from 11 861 arterial blood gas analyses. The relationship between fractions of HbF (%) and ROP was evaluated. RESULTS: The mean (SD) gestational age (GA) at birth was 26.4 (1.8) weeks. In total, 104 (27 %) infants developed ROP. Higher fraction of HbF (%) was associated with a lower prevalence of ROP, OR by a 10% increase 0.83 (95% CI: 0.71 to 0.97; p=0.019), following adjustment for GA at birth, small for GA and sex. Infants with HbF (%) in the lowest quartile had OR of 22.0 (95% CI: 8.1 to 59.2; p<0.001) for ROP development compared with those in the highest quartile. The predictive ability (area under the curve) of HbF (%) in the full model during the first week was 0.849 for ROP. CONCLUSIONS: Early low fraction of HbF is independently associated with abnormal retinal neurovascular development in the very preterm infant. The potential benefit of minimising blood loss on development of ROP will be investigated in a multicenter randomised trial (NCT04239690).

Fetal haemoglobin and bronchopulmonary dysplasia in neonates: an observational study.

OBJECTIVE: Early decrease in fetal haemoglobin (HbF) is an indicator of loss of endogenous blood components that might have predictive value for development of bronchopulmonary dysplasia (BPD). The link between HbF and BPD has not been evaluated. DESIGN: Retrospective observational study. SETTING: Tertiary level neonatal intensive care unit, referral centre for Southern Sweden. PATIENTS: 452 very preterm infants (<30 gestational weeks) born 2009-2015. INTERVENTIONS: Regular clinical practice. MAIN OUTCOME MEASURES: Mean HbF, haemoglobin (Hb) and partial oxygen pressure (PaO2) levels calculated from 11 861 arterial blood gas analyses postnatal week 1. Relationship between HbF (%) and BPD (requirement of supplemental oxygen at 36 weeks' postmenstrual age) and the modifying influence of PaO2 (kPa) and total Hb (g/L) was evaluated. RESULTS: The mean gestational age (GA) at birth was 26.4 weeks, and 213 (56%) infants developed BPD. A 10% increase in HbF was associated with a decreased prevalence of BPD, OR 0.64 (95% CI 0.49 to 0.83; p<0.001). This association remained when adjusting for mean PaO2 and Hb. Infants with an HbF in the lowest quartile had an OR of 27.1 (95% CI 11.6 to 63.4; p<0.001) for development of BPD as compared with those in the highest quartile. The area under the curve for HbF levels and development of BPD in the full statistical model was 0.871. CONCLUSIONS: Early rapid postnatal decline in HbF levels was associated with development of BPD in very preterm infants. The association between HbF and BPD was not mediated by increased oxygen exposure. The potential benefit of minimising loss of endogenous blood components on BPD outcome will be investigated in a multicentre randomised trial.

Analysis of Brain Injury Biomarker Neurofilament Light and Neurodevelopmental Outcomes and Retinopathy of Prematurity Among Preterm Infants.

Importance: Circulating levels of neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) are important in the course of brain injury in adults, but longitudinal postnatal circulating levels in preterm infants have not been investigated. Objectives: To examine postnatal longitudinal serum levels of NfL and GFAP in preterm infants during the first 15 weeks of life and to explore possible associations between these biomarkers, neonatal morbidities, and neurodevelopmental outcomes at 2 years. Design, Setting, and Participants: This cohort study used data from 3 clinical studies, including 221 infants born before 32 weeks gestational age (GA) from 1999 to 2015; neurodevelopmental outcomes were evaluated in 120 infants. Data were collected at tertiary-level neonatal intensive care units in Gothenburg, Lund, and Uppsala, Sweden. Data analysis was conducted from January to October 2020. Exposure: Preterm birth. Main Outcomes and Measures: Serum NfL and GFAP levels, retinopathy of prematurity (ROP), intraventricular hemorrhage, and Bayley Scales of Infant Development II and III at 2 years of age, analyzed by multivariate logistic regression measured by odds ratio (OR), and receiver operating characteristic curve (ROC) analysis. Area under the curve (AUC) was also measured. Results: The 221 included infants (108 [48.9%] girls) had a mean (SD) GA at birth of 26.5 (2.1) weeks and a mean (SD) birth weight of 896 (301) grams. NfL levels increased after birth, remaining high during the first 4 weeks of life before declining to continuously low levels by postnatal age 12 weeks (median [range] NfL level at birth: 58.8 [11.5-1371.3] ng/L; 1 wk: 83.5 [14.1-952.2] ng/L; 4 wk: 24.4 [7.0-306.0] ng/L; 12 wk: 9.1 [3.7-57.0] ng/L). In a binary logistic regression model adjusted for GA at birth, birth weight SD score, Apgar status at 5 minutes, and mode of delivery, the NfL AUC at weeks 2 to 4 was independently associated with any ROP (OR, 4.79; 95% CI, 2.17-10.56; P < .001). In an exploratory analysis adjusted for GA at birth and sex, NfL AUC at weeks 2 to 4 was independently associated with unfavorable neurodevelopmental outcomes at 2 years corrected age (OR per 10-unit NfL increase, 1.07; 95% CI, 1.02-1.13; P = .01). Longitudinal GFAP levels were not significantly associated with neonatal morbidity or neurodevelopmental outcome. Conclusions and Relevance: In this study, high NfL levels during the first weeks of life were associated with ROP and poor neurodevelopmental outcomes at 2 years of age. Associations between NfL and later neurovascular development in infants born prematurely should be investigated further.

Effect of Enteral Lipid Supplement on Severe Retinopathy of Prematurity: A Randomized Clinical Trial.

Importance: Lack of arachidonic acid (AA) and docosahexaenoic acid (DHA) after extremely preterm birth may contribute to preterm morbidity, including retinopathy of prematurity (ROP). Objective: To determine whether enteral supplementation with fatty acids from birth to 40 weeks' postmenstrual age reduces ROP in extremely preterm infants. Design, Setting, and Participants: The Mega Donna Mega trial, a randomized clinical trial, was a multicenter study performed at 3 university hospitals in Sweden from December 15, 2016, to December 15, 2019. The screening pediatric ophthalmologists were masked to patient groupings. A total of 209 infants born at less than 28 weeks' gestation were tested for eligibility, and 206 infants were included. Efficacy analyses were performed on as-randomized groups on the intention-to-treat population and on the per-protocol population using as-treated groups. Statistical analyses were performed from February to April 2020. Interventions: Infants received either supplementation with an enteral oil providing AA (100 mg/kg/d) and DHA (50 mg/kg/d) (AA:DHA group) or no supplementation within 3 days after birth until 40 weeks' postmenstrual age. Main Outcomes and Measures: The primary outcome was severe ROP (stage 3 and/or type 1). The secondary outcomes were AA and DHA serum levels and rates of other complications of preterm birth. Results: A total of 101 infants (58 boys [57.4%]; mean [SD] gestational age, 25.5 [1.5] weeks) were included in the AA:DHA group, and 105 infants (59 boys [56.2%]; mean [SD] gestational age, 25.5 [1.4] weeks) were included in the control group. Treatment with AA and DHA reduced severe ROP compared with the standard of care (16 of 101 [15.8%] in the AA:DHA group vs 35 of 105 [33.3%] in the control group; adjusted relative risk, 0.50 [95% CI, 0.28-0.91]; P = .02). The AA:DHA group had significantly higher fractions of AA and DHA in serum phospholipids compared with controls (overall mean difference in AA:DHA group, 0.82 mol% [95% CI, 0.46-1.18 mol%]; P < .001; overall mean difference in control group, 0.13 mol% [95% CI, 0.01-0.24 mol%]; P = .03). There were no significant differences between the AA:DHA group and the control group in the rates of bronchopulmonary dysplasia (48 of 101 [47.5%] vs 48 of 105 [45.7%]) and of any grade of intraventricular hemorrhage (43 of 101 [42.6%] vs 42 of 105 [40.0%]). In the AA:DHA group and control group, respectively, sepsis occurred in 42 of 101 infants (41.6%) and 53 of 105 infants (50.5%), serious adverse events occurred in 26 of 101 infants (25.7%) and 26 of 105 infants (24.8%), and 16 of 101 infants (15.8%) and 13 of 106 infants (12.3%) died. Conclusions and Relevance: This study found that, compared with standard of care, enteral AA:DHA supplementation lowered the risk of severe ROP by 50% and showed overall higher serum levels of both AA and DHA. Enteral lipid supplementation with AA:DHA is a novel preventive strategy to decrease severe ROP in extremely preterm infants. Trial Registration: ClinicalTrials.gov Identifier: NCT03201588.

IGF1, serum glucose, and retinopathy of prematurity in extremely preterm infants.

BACKGROUNDHyperglycemia, insulin insensitivity, and low IGF1 levels in extremely preterm infants are associated with an increased risk of retinopathy of prematurity (ROP), but the interactions are incompletely understood.METHODSIn 117 extremely preterm infants, serum glucose levels and parenteral glucose intake were recoded daily in the first postnatal week. Serum IGF1 levels were measured weekly. Mice with oxygen-induced retinopathy alone versus oxygen-induced retinopathy plus streptozotocin-induced hyperglycemia/hypoinsulinemia were assessed for glucose, insulin, IGF1, IGFBP1, and IGFBP3 in blood and liver. Recombinant human IGF1 was injected to assess the effect on glucose and retinopathy.RESULTSThe highest mean plasma glucose tertile of infants positively correlated with parenteral glucose intake [r(39) = 0.67, P < 0.0001]. IGF1 plasma levels were lower in the high tertile compared with those in low and intermediate tertiles at day 28 (P = 0.038 and P = 0.03). In high versus lower glucose tertiles, ROP was more prevalent (34 of 39 versus 19 of 39) and more severe (ROP stage 3 or higher; 71% versus 32%). In oxygen-induced retinopathy, hyperglycemia/hypoinsulinemia decreased liver IGF1 expression (P < 0.0001); rh-IGF1 treatment improved normal vascular regrowth (P = 0.027) and reduced neovascularization (P < 0.0001).CONCLUSIONIn extremely preterm infants, high early postnatal plasma glucose levels and signs of insulin insensitivity were associated with lower IGF1 levels and increased ROP severity. In a hyperglycemia retinopathy mouse model, decreased insulin signaling suppressed liver IGF1 production, lowered serum IGF1 levels, and increased neovascularization. IGF1 supplementation improved retinal revascularization and decreased pathological neovascularization. The data support IGF1 as a potential treatment for prevention of ROP.TRIAL REGISTRATIONClinicalTrials.gov NCT02760472 (Donna Mega).FUNDINGThis study has been supported by the Swedish Medical Research Council (14940, 4732, 20144-01-3, and 21144-01-3), a Swedish government grant (ALFGB2770), Lund medical faculty grants (ALFL, 11615 and 11601), the Skåne Council Foundation for Research and Development, the Linnéa and Josef Carlsson Foundation, the Knut and Alice Wallenberg Foundation, the NIH/National Eye Institute (EY022275, EY017017, EY017017-13S1, and P01 HD18655), European Commission FP7 project 305485 PREVENT-ROP, Deutsche Forschungsgemeinschaft (CA-1940/1-1), and Stiftelsen De Blindas Vänner.

Docosahexaenoic Acid and Arachidonic Acid Levels Are Associated with Early Systemic Inflammation in Extremely Preterm Infants.

Fetal and early postnatal inflammation have been associated with increased morbidity in extremely preterm infants. This study aimed to demonstrate if postpartum levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) were associated with early inflammation. In a cohort of 90 extremely preterm infants, DHA and AA in cord blood, on the first postnatal day and on postnatal day 7 were examined in relation to early systemic inflammation, defined as elevated C-reactive protein (CRP) and/or interleukin-6 (IL-6) within 72 h from birth, with or without positive blood culture. Median serum level of DHA was 0.5 mol% (95% CI (confidence interval) 0.2-0.9, P = 0.006) lower than the first postnatal day in infants with early systemic inflammation, compared to infants without signs of inflammation, whereas levels of AA were not statistically different between infants with and without signs of inflammation. In cord blood, lower serum levels of both DHA (correlation coefficient -0.40; P = 0.010) and AA (correlation coefficient -0.54; p < 0.001) correlated with higher levels of IL-6. Levels of DHA or AA did not differ between infants with and without histological signs of chorioamnionitis or fetal inflammation. In conclusion, serum levels of DHA at birth were associated with the inflammatory response during the early postnatal period in extremely preterm infants.

C-Peptide Suppression During Insulin Infusion in the Extremely Preterm Infant Is Associated With Insulin Sensitivity.

CONTEXT: Little is known about the individual response of glucose-regulating factors to administration of exogenous insulin infusion in extremely preterm infants. OBJECTIVE: To evaluate longitudinal serum concentrations of insulin, C-peptide, and plasma glucose levels in a high-frequency sampling regimen in extremely preterm infants treated with insulin because of hyperglycemia. DESIGN: Prospective longitudinal cohort study. SETTING: Two university hospitals in Sweden between December 2015 and September 2016. PATIENTS AND INTERVENTION: Serum samples were obtained from nine extremely preterm infants, gestational age between 22 (+3) and 26 (+5) weeks (+ days), with hyperglycemia (plasma-glucose >10 mmol/L) at the start of insulin infusion, at 12, 24, and every 24 hours thereafter during ongoing infusion, and 12, 24, and 72 hours after the end of insulin infusion. MAIN OUTCOME MEASURES: Longitudinal serum concentrations of insulin and C-peptide and plasma glucose levels. RESULTS: During insulin infusion, the serum C-peptide concentrations decreased compared with at start of infusion (P = 0.036), and then increased after ending the infusion. Individual insulin sensitivity based on the nonfasting plasma glucose/insulin ratio at the start of insulin infusion correlated with the initial decrease in serum ΔC-peptide[after 12h] (P = 0.007) and the degree of lasting decrease in serum ΔC-peptide[after end of infusion] (P = 0.015). CONCLUSION: Exogenous insulin infusion suppressed the C-peptide concentration to individually different degrees. In addition, the effect of insulin infusion on ß cells may be linked to individual insulin sensitivity, where a low insulin sensitivity resulted in a more pronounced decrease in C-peptide during insulin infusion.