Thromboxane B2 production by fetal and neonatal platelets: effect of idiopathic respiratory distress syndrome and birth asphyxia

Hemostasis in Neonates with Perinatal Hypoxia—Laboratory Approach: A Systematic Review

Birth asphyxia, with an estimated prevalence of 1 to 6 per 1,000 live births, may lead to multiorgan dysfunction due to impaired oxygen and/or blood supply to various organ systems, including the hemostatic system. Coagulopathy, a common complication of perinatal asphyxia, has been described since the 1960s. The aim of this study was to systematically review the literature for records on the use of hemostasis tests in the evaluation of coagulation disorders, in neonates who had suffered from perinatal hypoxia or asphyxia. We identified published studies by searching PubMed and Scopus, up until April 2022. The literature search retrieved 37 articles fulfilling the inclusion criteria of the review. According to the bibliography, thrombocytopenia is commonly associated with perinatal hypoxia/asphyxia. The thrombocytopenia is usually described as mild and platelets return to normal levels by the 10th day of life. Additionally, hypoxic neonates usually present with a hypocoagulable profile, as reflected by the prolongation of standard coagulation tests, including prothrombin time, activated partial thromboplastin time, and international normalized ratio, findings commonly associated with disseminated intravascular coagulation, and by the reduction of the levels of the physiologic inhibition of coagulation system. A few studies thus far using ROTEM/TEG in hypoxic neonates have come to the same conclusion as well; hypoxic newborns seem to be characterized by a hypocoagulable profile compared with healthy neonates. It should be emphasized, however, that standard coagulation tests provide only a rough estimation of the true bleeding or thrombotic risk of hypoxic neonates. On the contrary, viscoelastic methods seem to be more precise in the early detection of hemostasis disorders in the neonatal population. However, until now, there was uncertainty as to the most appropriate coagulation assays for diagnosis and management of coagulation derangement in neonates with perinatal hypoxia indicating the need for further research on this field.

Fetal and neonatal prostacyclin and thromboxane in relation to mode of delivery

To study whether prostacyclin and thromboxane A2 might play a role in neonatal adaption pieces of the umbilical arteries of infants born vaginally (n = 18) or by elective caesarean section (n = 11) were superfused in vitro and the release of 6-keto-PGF1a (hydration product of prostacyclin) and thromboxane B2 (metabolite of thromboxane A2) measured by radioimmunoassay. In addition, the capacity of fetal platelets to produce thromboxane A2 and the neonatal urinary concentrations of 6-keto-PGF1a were measured. Infants born by caesarean section had lower diastolic blood pressure, higher heart rate, and smaller differences between rectal and skin temperature compared with infants born vaginally during the first two hours of life. The only difference encountered in the prostanoids between the groups was reduced urinary excretion of 6-keto-PGF1a in infants born by caesarean section, whose release of 6-keto-PGF1a by the umbilical artery was positively correlated with heart rate, respiration frequency, and dermal temperature. Thus prostacyclin may be a regulatory determinant, particularly in infants born by caesarean section.

Dietary fatty acids and platelet thromboxane production in puerperal women and their offspring

The effects of the ratio of polyunsaturated to saturated fatty acids in the diet of puerperal women on maternal and neonatal fatty acids and thromboxane A2 synthesis were studied in 91 mother-infant pairs on the fourth to fifth day after delivery. The mothers received a diet with either a low (0.1) or a high (1.5) polyunsaturated to saturated fatty acid ratio for 4 to 5 days. The fatty acid composition in maternal and neonatal serum and in breast milk was determined in 34 mother-infant pairs from both dietary groups. The capacity of the platelets to produce thromboxane B2, a stable metabolite of thromboxane A2, was determined in another 57 mother-infant pairs. The percentage of linoleic acid was increased in maternal and neonatal sera as well as in the breast milk in the group with a high dietary polyunsaturated to saturated fatty acid ratio, whereas the content of arachidonic acid was increased only in maternal serum. This was accompanied by increased platelet thromboxane B2 production in the mothers, and maternal and neonatal thromboxane B2 synthesis correlated significantly with each other (r = 0.43, p less than 0.05). This finding may provide therapeutic possibilities in the future.