Preterm delivery is the leading factor causing neonatal mortality and morbidity. We have conducted a PubMed literature search to obtain an update on the etiology, diagnostic problems and therapeutic considerations of preterm delivery. Approximately 5-10% of all births are premature. Preterm labor is associated with preterm rupture of membranes, cervical incompetence, polyhydramnion, fetal and uterine anomalies, infections, social factors, stress, smoking, heavy work and other risk factors. The diagnosis is made on the patients presenting symptoms, clinical findings and of progressive effacement and dilatation of the cervix. Biochemical markers of preterm delivery are of minor importance in daily clinical work. Measurement of the cervix, however, is a practical and valuable tool to predict preterm delivery. Cervical cerclage can be useful in selected cases. Antibiotics may help to prevent preterm labor in cases of known etiologic agents (e.g. preterm rupture of membranes and urinary infection). The use of tocolytic agents such as beta-sympathetic receptor stimulators can be advocated for a few days. There is evidence that their long-term use is not beneficial and could even be harmful to the fetus. Calcium channel blockers (nifedipine) and a new selective oxytocin receptor antagonist, atosiban, appear to be as effective as beta-sympathomimetic drugs on uterine contractions with fewer side-effects. Prostaglandin synthetase inhibitors such as indomethacin may prevent uterine contractions and can be used prior to the 32nd week of pregnancy. A single course of corticosteroid treatment in two doses of 12 mg betamethasone or 6 mg of dexamethasone is important for the prevention of respiratory distress between the 24th and 34th weeks of pregnancy. Multiple doses may be harmful and should be avoided. In these cases management should depend on gestation age (fetal maturity). Uterine contractions after 34 weeks' gestation are not an indication for tocolytic treatment.
Both preeclampsia and the HELLP syndrome have their origin in the placenta. The aim of this study is to review genetic factors involved in development of preeclampsia and the HELLP syndrome using literature search in PubMed. A familial cohort links chromosomes 2q, 5q, and 13q to preeclampsia. The chromosome 12q is coupled with the HELLP syndrome. The STOX1 gene, the ERAP1 and 2 genes, the syncytin envelope gene, and the −670 Fas receptor polymorphisms are involved in the development of preeclampsia. The ACVR2A gene on chromosome 2q22 is also implicated. The toll-like receptor-4 (TLR-4) and factor V Leiden mutation participate both in development of preeclampsia and the HELLP syndrome. Carriers of the TT and the CC genotype of the MTHFR C677T polymorphism seem to have an increased risk of the HELLP syndrome. The placental levels of VEGF mRNA are reduced both in women with preeclampsia and in women with the HELLP syndrome. The BclI polymorphism is engaged in development of the HELLP syndrome but not in development of severe preeclampsia. The ACE I/D polymorphism affects uteroplacental and umbilical artery blood flows in women with preeclampsia. In women with preeclampsia and the HELLP syndrome several genes in the placenta are deregulated. Preeclampsia and the HELLP syndrome are multiplex genetic diseases.
Preterm delivery is the leading factor causing neonatal mortality and morbidity. We have conducted a PubMed literature search to obtain an update on the etiology, diagnostic problems and therapeutic considerations of preterm delivery. Approximately 5-10% of all births are premature. Preterm labor is associated with preterm rupture of membranes, cervical incompetence, polyhydramnion, fetal and uterine anomalies, infections, social factors, stress, smoking, heavy work and other risk factors. The diagnosis is made on the patients presenting symptoms, clinical findings and of progressive effacement and dilatation of the cervix. Biochemical markers of preterm delivery are of minor importance in daily clinical work. Measurement of the cervix, however, is a practical and valuable tool to predict preterm delivery. Cervical cerclage can be useful in selected cases. Antibiotics may help to prevent preterm labor in cases of known etiologic agents (e.g. preterm rupture of membranes and urinary infection). The use of tocolytic agents such as b-sympathetic receptor stimulators can be advocated for a few days. There is evidence that their longterm use is not beneficial and could even be harmful to the fetus. Calcium channel blockers (nifedipine) and a new selective oxytocin receptor antagonist, atosiban, appear to be as effective as b-sympathomimetic drugs on uterine contractions with fewer side-effects. Prostaglandin synthetase inhibitors such as indomethacin may prevent uterine contractions and can be used prior to the 32nd week of pregnancy. A single course of corticosteroid treatment in two doses of 12 mg betamethasone or 6 mg of dexamethasone is important for the prevention of respiratory distress between the 24th and 34th weeks of pregnancy. Multiple doses may be harmful and should be avoided. In these cases management should depend on gestation age (fetal maturity). Uterine contractions after 34 weeks' gestation are not an indication for tocolytic treatment.
The central rationale of tocolysis for preterm labor (PTL) is to delay delivery for at least 48 h to allow for transfer of the mother to a tertiary facility and for corticosteroids to induce surfactant production in fetal lungs. Beta-mimetics decrease the number of women in preterm labor giving birth within 48 h without reducing adverse neonatal outcomes. Calcium channel blockers inclusive of nifedipine decrease the adverse neonatal outcomes by significantly delaying delivery. Atosiban has the best maternal and fetal safety profile but does not seem to reduce neonatal complications. Magnesium sulfate is controversial as a tocolytic, but is valuable as a neuroprotective agent and for treatment of eclamptic seizures. Indomethacin may be a reasonable first choice for acute tocolytsis in gestational ages less than 32 weeks' gestation. Prolonged use (>48 h) should be avoided. Transdermal nitroglycerin can reduce neonatal morbidity and mortality as a result of decreased risk of birth before 28 weeks' gestation. Nifedipine may be a reasonable first choice because it is easy to administer and also of limited side effects relative to β2-mimetics. Tocolysis does not appear to significantly lengthen the gestational age beyond seven days.
Oxidative stress is a consequence of reduction in the antioxidant capacity and excessive production of reactive oxygen and nitrogen species (ROS). Oxidative agents, which are overproduced due to ischemic-reperfusion injury in the placenta, may overwhelm the normal antioxidant activity. This imbalance is a key feature in the pathogenesis of preeclampsia. A decrease in glutathione peroxidase (GPX) activity is associated with the synthesis of vasoconstrictive eicosanoids such as F2-isoprostanes and thromboxane, which are known to be upregulated in preeclampsia. Biochemical markers of lipid peroxidation, such as malondialdehyde and F2-isoprostane in the placenta, are also increased. Adhesion molecules participate in the pathophysiology of preeclampsia by contributing to a reduced invasion by the trophoblast and increased vascular endothelial damage. Superoxide dismutase (SOD), catalase (CAT) and GPX play important roles counteracting oxidative stress. Other antioxidant factors participate in the etiology of preeclampsia. Levels of antioxidants such as Lycopene, Coenzyme 10, as well as some vitamins, are reduced in preeclamptic gestations.
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