Effect of Maternal Smoking on Plasma and Urinary Measures of Vitamin E Isoforms in the First Month after Extreme Preterm Birth

Strategies to Prevent Severe Retinopathy of Prematurity: A 2020 Update and Meta-analysis

The incidence of retinopathy of prematurity (ROP) is showing an increasing trend in the United States. This may be because of increasing survival rates among extremely preterm infants (<25 weeks' gestation) and targeting higher oxygen saturation. Five randomized clinical trials of low versus high oxygen saturation target ranges found increased mortality in the low oxygen saturation target group and an increased incidence of ROP in the high oxygen saturation target group. The American Academy of Pediatrics recommends using an oxygen saturation target range of 90% to 95% in extremely low-birthweight infants. The change of practice to target this higher oxygen saturation range, from admission until discharge, may be contributing to the increasing incidence of ROP in extremely preterm infants. To decrease the incidence of ROP without increasing mortality, 2 new cohort trials suggest gradually increasing oxygen saturation targets as preterm infants mature. There is evidence that human milk, vitamin A, and omega-3 fatty acids can help, in addition to continuous oxygen saturation monitoring, to decrease the risk of ROP. We review this literature and provide a meta-analysis to evaluate the evidence.

Recent advances in antenatal factors predisposing to bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) remains a major cause of late morbidities and death after preterm birth. BPD is characterized by an arrest of vascular and alveolar growth and high risk for pulmonary hypertension; yet mechanisms contributing to its pathogenesis and early strategies to prevent BPD are poorly understood. Strong epidemiologic studies have shown that the "new BPD" reflects the long-lasting impact of antenatal factors on lung development, partly due to placental dysfunction, as reflected in recent data from animal models. Improved understanding of mechanisms through which antenatal stress alters placental function and contributes to BPD may lead to preventive therapies.

Update on Vitamin E and Its Potential Role in Preventing or Treating Bronchopulmonary Dysplasia

Vitamin E is obtained only through the diet and has a number of important biological activities, including functioning as an antioxidant. Evidence that free radicals may contribute to pathological processes such as bronchopulmonary dysplasia (BPD), a disease of prematurity associated with increased lung injury, inflammation and oxidative stress, led to trials of the antioxidant vitamin E (α-tocopherol) to prevent BPD with variable results. These trials were all conducted at supraphysiologic doses and 2 of these trials utilized a formulation containing a potentially harmful excipient. Since 1991, when the last of these trials was conducted, both neonatal management strategies for minimizing oxygen and ventilator-related lung injury and our understanding of vitamin E isoforms in respiratory health have advanced substantially. It is now known that there are differences between the effects of vitamin E isoforms α-tocopherol and γ-tocopherol on the development of respiratory morbidity and inflammation. What is not known is whether improvements in physiologic concentrations of individual or combinations of vitamin E isoforms during pregnancy or following preterm birth might prevent or reduce BPD development. The answers to these questions require adequately powered studies targeting pregnant women at risk of preterm birth or their premature infants immediately following birth, especially in certain subgroups that are at increased risk of vitamin E deficiency (e.g., smokers). The objective of this review is to compile, update, and interpret what is known about vitamin E isoforms and BPD since these first studies were conducted, and suggest future research directions.