Fetal oxidative stress, micronutrient deficiency and risk of retinopathy of prematurity: a nested case-control study

Improved linear growth after routine zinc supplementation in preterm very low birth weight infants

BACKGROUND

This study was designed (1) to compare growth, morbidity and mortality in < 33-week gestational age (GA) (very preterm, VPT) or very low birth weight (BW < 1500 grams, VLBW) infants before (Epoch-1) and after implementing routine enteral zinc (Zn) supplementation (Epoch-2) to meet recommendations, and (2) to assess serum Zn levels and associated variables.

METHODS

Single-center prospective cohort of 826 infants. The primary outcome was the change (Δ) in Z-scores of accurate length (Δlengthz), weight and head circumference from birth to discharge home.

RESULTS

In Epoch-2 vs Epoch-1 Δlengthz adjusted for confounding variables increased by 0.27 [95% confidence interval (CI) 0.13, 0.42, P < 0.001]. However, morbidity and mortality did not change. In Epoch-2 Zn decreased with GA and postnatal age: low ( < 0.74 mcg/mL) levels were observed in 51% infants. Retinopathy of prematurity (ROP) was independently associated with the lowest Zn [adjusted odds ratio 0.042 (CI 0.006, 0.306), area under the curve=0.928].

CONCLUSION

Routine enteral Zn supplementation was independently associated with improved linear growth but did not prevent occurrence of low Zn. ROP was independently associated with the lowest Zn.

IMPLICATIONS

Multicenter studies are needed to assess whether dosage of enteral Zn should be increased and whether Zn could help prevent ROP.

IMPACT

Implementation of routine enteral zinc (Zn) supplementation was associated with improved linear growth from birth to discharge and a more frequent physiologic growth curve in preterm very low birth weight infants. Serum Zn levels decreased with gestational age and with postnatal age. Low serum Zn levels were observed frequently despite routine Zn supplementation as currently recommended, which suggests a need to re-evaluate current enteral zinc supplementation guidelines for this population. Retinopathy of prematurity among infants < 33 weeks' gestation was independently associated with low gestational age, low birthweight, stage of bronchopulmonary dysplasia and the lowest serum Zn level.

Analysis of zinc and copper levels in very low birth weight infants using human milk additives: phase 1 trial findings

OBJECTIVE

The aim of this study was to assess whether the micronutrients zinc and copper, provided by human milk additives, are sufficient for very low birth weight preterm infants.

METHOD

A phase 1 randomized double-blind controlled trial was conducted with very low birth weight preterm infants. This is a secondary analysis of copper and zinc. Sixty-six newborns were part of the initial sample, with forty participating and reaching the final stage of the study. Inclusion criteria were: gestational age less than 37 weeks, birth weight greater than or equal to 750 g and less than or equal to 1500 g, small or appropriate for gestational age, exclusively receiving human milk at a volume greater than or equal to 100 mL per kilogram per day, and hemodynamically stable. Participants were randomly assigned to two groups: intervention, Lioneo (received human milk with additive based on lyophilized human milk), n = 20, and control, HMCA (received human milk with commercial additive based on cow's milk protein), n = 20, and their serum levels of zinc and copper were measured on the first and twenty-first days.

RESULTS

There was a reduction in intragroup zinc serum levels from the first to the twenty-first day of the study (p < 0.01). There was no intergroup difference. No difference was found in serum copper levels.

CONCLUSION

Human milk additives were not sufficient to maintain adequate zinc serum levels in very low birth weight newborns. It was not possible to affirm whether human milk additives were sufficient to maintain adequate serum copper levels in the studied sample. UTN: U1111-1220-0550.

Serum Zinc Levels in Preterm Newborns and its Relation with Retinopathy of Prematurity

Background

With the increased survival of preterm babies, retinopathy of prematurity (ROP) has become the leading cause of preventable childhood blindness. It is caused by oxidative damage to the immature retina and zinc may help in the prevention of ROP owing to its antioxidant properties.

Objective

To measure serum zinc levels in preterm neonates and study its association with the development of ROP.

Methods

A total of 360 preterm neonates of gestational age between 28 completed weeks to <37 weeks were included in this observational cross-sectional study. Serum zinc levels of the neonates aging <24 hours of life were measured at the time of admission in NICU by spectrophotometry. Taking the reference range of serum zinc levels between 70 to 150 mcg/dL babies were arbitrarily divided into 2 groups (<70 and >70 mcg/dL). ROP screening was done at appropriate postnatal age by indirect ophthalmoscopy. The results were analyzed by the SPSS software version.

Results

The mean serum zinc level was 114.99±54.47 mcg/dL. The overall prevalence of ROP was 26%; of which, 10% of neonates had severe ROP (≥stage 3). A significant association was found between gestational age and birth weight with ROP. Oxygen supplementation, respiratory distress syndrome, surfactant use, antibiotic use >7 days, and low serum zinc levels (<70 mcg/dL) were significant risk factors on univariate analysis and after multivariate analysis, gestational age, surfactant use, and low serum zinc levels (<70 mcg/dL) came out to be independent risk factors for ROP.

Conclusion

There was a statistically significant association of low serum zinc levels with the development of ROP and it was independent of other risk factors associated with ROP.

Refractive status and retinal morphology in children with a history of intravitreal ranibizumab for retinopathy of prematurity

This study investigated the characteristics of refractive status, visual acuity, and retinal morphology in children with a history of receiving intravitreal ranibizumab for retinopathy of prematurity (ROP). Children 4-6 years of age were enrolled and divided into the following four groups: group 1, children with a history of ROP who had been treated with intravitreal ranibizumab; group 2, children with a history of ROP who had not received any treatment; group 3, premature children without ROP; and group 4, full-term children. Refractive status, peripapillary retinal nerve fiber layer (RNFL), and macular thickness were measured. A total of 204 children were enrolled. In group 1, myopic shift was not noted, but poorer best corrected visual acuity (BCVA) and shorter axial length were observed. Significantly lower peripapillary RNFL thickness in the average total and superior quadrant, higher central subfield thickness, lower parafoveal retinal thickness in average total, superior, and nasal and temporal quadrants were observed in group 1 than in the other groups. The poor BCVA in patients with ROP was correlated with the lower RNFL thickness in the superior quadrant.   Conclusion: Children with a history of type 1 ROP treated with ranibizumab did not show a myopic shift but did show abnormal retinal morphology and the poorest BCVA among all groups. We suggest that pediatric ophthalmologists should always pay attention to visual development in patients with ROP with a history of intravitreal ranibizumab. What is Known: • Anti-VEGF is efficiently and widely used in the treatment of type 1 retinopathy of prematurity (ROP), and different anti-VEGF agents are associated with different prevalence of myopia. • Patients with ROP who receive treatment such as laser therapy or cryotherapy have abnormal macular development and retinal nerve fiber layer (RNFL) thickness. What is New: • Children with a history of ROP treated with intravitreal ranibizumab did not show a myopic shift but did show poor BCVA at 4-6 years of age. • Abnormal macular morphology and lower peripapillary RNFL thickness were found in these children.

Modifiable Risk Factors and Preventative Strategies for Severe Retinopathy of Prematurity

Severe ROP is characterized by the development of retinal fibrovascular proliferation that may progress to retinal detachment. The purpose of this report is to review five of the most common and well-studied perinatal and neonatal modifiable risk factors for the development of severe ROP. Hyperoxemia, hypoxia, and associated prolonged respiratory support are linked to the development of severe ROP. While there is a well-established association between clinical maternal chorioamnionitis and severe ROP, there is greater variability between histologic chorioamnionitis and severe ROP. Neonatal sepsis, including both bacterial and fungal subtypes, are independent predictors of severe ROP in preterm infants. Although there is limited evidence related to platelet transfusions, the risk of severe ROP increases with the number and volume of red blood cell transfusions. Poor postnatal weight gain within the first six weeks of life is also strongly tied to the development of severe ROP. We also discuss preventative strategies that may reduce the risk of severe ROP. Limited evidence-based studies exist regarding the protective effects of caffeine, human milk, and vitamins A and E.

Neonatal diseases and oxidative stress in premature infants: an integrative review

OBJECTIVE

To describe the relationship of oxidative stress and antioxidant biomarkers in cord blood of premature newborns and the prognosis of diseases in the neonatal period.

SOURCES

This study consists of an integrative review. Searches were conducted in electronic databases Scopus, PubMed, Web of Science, and Medline/Lilacs through the Virtual Library on Health Issues, using the descriptors: "premature infants", "preterm infants", "preterm birth", "preterm", "oxidative stress", "antioxidants", "infant, premature, diseases" and "cord blood". Original articles published between 2016 and 2021 in Portuguese, English, or Spanish, which analyzed oxidative stress and/or antioxidant levels through cord blood of premature newborns and evaluated clinical outcomes, were included.

SUMMARY OF THE FINDINGS

Of the 1,003 studies reviewed, after exclusion of duplicate articles, analysis of titles, abstracts, and full texts, 18 articles were included. 72.2% (n = 13) of analyzed studies reported a positive association between oxidative stress and the development of prematurity-related diseases; 27.7% (n = 5) showed no significant relation. Outcomes that showed a positive association were: intrauterine growth restriction, necrotizing enterocolitis, bronchopulmonary dysplasia, intraventricular hemorrhage, fetal inflammatory response syndrome, early-onset neonatal sepsis, retinopathy of prematurity, morbidity, and mortality.

CONCLUSION

The analysis of oxidative stress and antioxidants in cord blood of premature newborns may be useful in the prognosis of some pathologies. The consequences of oxidative damage are known to be associated with increased morbidity in the short and long term. Further investigation is needed in this population in order to define normality parameters of biomarkers, clinical manifestations, diagnosis and treatment of these conditions.

Early Vitamin A Supplementation for Prevention of Short-Term Morbidity and Mortality in Very-Low-Birth-Weight Infants: A Systematic Review and Meta-Analysis

Background

Vitamin A plays an important role in the development and maintenance of the normal function of organs and systems. Premature infants have low levels of vitamin A, which may be associated with an increased risk of developing disease. This study aimed to evaluate the effects of vitamin A supplementation on short-term morbidity and mortality in very-low-birth-weight (VLBW) infants.

Methods

We used PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, and Web of Science to conduct a literature search of studies published before January 1, 2022, to be included in our meta-analysis. The analysis included randomized controlled trials that compared the effects of vitamin A supplementation on VLBW infants (birth weight <1,500 g) and controls given a placebo or no treatment. The certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) guidelines.

Results

Twelve randomized controlled trials were included in the meta-analysis, and 2,111 infants were pooled and analyzed. The overall risk of bias was not serious in the included studies. Vitamin A supplementation for reducing the incidence of bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age seems to be limited [risk ratio (RR):0.85; 95% confidence intervals (CI): 0.70-1.04; 8 studies, 1,595 infants, very-low-certainty evidence], which is different from the previous systematic review. Length of hospital stay (mean difference: -12.67, 95% CI: -23.55 to -1.79; 6 studies, 739 infants, low-certainty evidence), and the incidence of vitamin A deficiency at 28 days postnatal age (RR: 0.08; 95% CI: 0.02-0.38; 3 studies, 358 infants, low-certainty evidence) were reduced in the vitamin A group. Besides, vitamin A supplementation seems to reduce the incidence of periventricular leukomalacia (RR: 0.68; 95% CI: 0.47-0.97; 4 studies, 1,224 infants, low-certainty evidence) and retinopathy of prematurity of any grade (RR: 0.61; 95% CI: 0.48-0.76; 4 studies, 463 infants, moderate-certainty evidence).

Conclusions

There is no sufficient evidence regarding vitamin A supplementation preventing BPD in VLBW infants. Vitamin A supplementation can reduce the incidence of vitamin A deficiency and retinopathy of prematurity of any grade, and may exert an effect of preventing periventricular leukomalacia.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42020211070.

Novel Potential Biomarkers for Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is the main risk factor for vision-threatening disease in premature infants with low birth weight. An accumulating number of independent studies have focused on ROP pathogenesis and have demonstrated that laser photocoagulation therapy and/or anti-VEGF treatment are effective. However, early diagnosis of ROP is still critical. At present, the main method of ROP screening is based on binocular indirect ophthalmoscopy. However, the judgment of whether ROP occurs and whether treatment is necessary depends largely on ophthalmologists with a great deal of experience. Therefore, it is essential to develop a simple, accurate and effective diagnostic method. This review describes recent findings on novel biomarkers for the prediction, diagnosis and prognosis of ROP patients. The novel biomarkers were separated into the following categories: metabolites, cytokines and growth factors, non-coding RNAs, iconography, gut microbiota, oxidative stress biomarkers, and others. Biomarkers with high sensitivity and specificity are urgently needed for the clinical applications of ROP. In addition, using non-invasive or minimally invasive methods to obtain samples is also important. Our review provides an overview of potential biomarkers of ROP.