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Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prematurity remains the major cause of perinatal mortality and morbidity in Singapore. Prevention of prematurity is therefore of vital importance. Epidemiological methods using historical variables have been superseded by ongoing pregnancy factors including work, exercise and cervical dilatation. PGF levels bear a positive correlation to duration and cervical dilatation but are not elevated at onset. PGE production is high in ruptured membranes. Progesterone and relaxin are potent inhibitors before labour. Infection must play an important role in developing countries as organisms not thought of to be pathogenic produce phospholipase A2. For prediction, cervical assessment and topography are proving important. In view of the dangerous side effects of tocolytic drugs and the difficulty in diagnosis of preterm labour, absence of fetal breathing is a useful index of progressive labour. In those labours that are advanced, whether to allow vaginal delivery or not will be determined by the presentation and condition of the fetus. The complementary role of other drugs to reduce morbidity from hyaline membrane disease and intraventricular haemorrhage is being studied. Fetal acidosis should be avoided and the infant delivered without trauma under optimal circumstances. In utero transfer to a facility with neonatal intensive care carries a better prognosis for the baby.
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PMID:Current concepts in the management of preterm labour. 269 76

Changes in circulating steroid hormones, the incidence of myometrial contractions, and the onset of labour were all monitored after administration of the 3 beta-hydroxysteroid dehydrogenase inhibitor, epostane, to chronically catheterized ewes and fetuses near term. In all animals the drug induced delivery 33-36 h after injection or infusion into the ewe with the birth of live healthy lambs which showed normal subsequent development. Epostane induced immediate, permanent falls in both maternal and fetal plasma progesterone concentrations, accompanied by increased PGF metabolite concentrations in the uterine vein beginning 15 min after treatment. Of the other hormonal changes observed, the most striking was the pronounced drop in both maternal and fetal plasma cortisol. In the fetus this fall was followed by increasing concentrations of circulating ACTH which eventually restored the cortisol levels. By 12-24 h after epostane a substantial overshoot had occurred and at 27-30 h the fetal plasma cortisol concentrations were as high as those seen during normal parturition at term. No significant changes in maternal plasma oestradiol-17 beta could be detected after epostane treatment or during labour. The incidence of slow myometrial contractions increased significantly during the second 3-h period after epostane, although their duration did not change. Contraction patterns typical of first stage labour were seen from 20 to 24 h. These results show that epostane may be used as a safe, predictable inducing agent in sheep if given 6-10 days before term; the lambs showed no signs of prematurity despite their lowered plasma cortisol concentrations which persisted for some hours before labour was induced.
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PMID:Effects on maternal and fetal steroid concentrations of induction of parturition in the sheep by inhibition of 3 beta-hydroxysteroid dehydrogenase. 283 51

In the perinatal period, glucocorticoids are frequently administered to enhance pulmonary maturity or prevent chronic lung disease of prematurity. Recently, it has been suggested that the perinatal exposure to glucocorticoids can be associated with unfavorable neurologic development. We studied the hypothesis that 24-h pretreatment with glucocorticoid might modify cerebrovascular responses to high and low partial arterial CO(2) tension in newborn animals in vivo. A closed cranial window was implanted over the left parietal cortex of 20 anesthetized ventilated newborn (<3 d old) pigs. The actual experiments were carried out in 15 pigs: eight pretreated with a total dose of 6 mg/kg of dexamethasone and seven controls. Five pigs were used for preliminary experiments as described in the text. Pial arteriolar diameters were measured during 1) baseline conditions (normocapnia), 2) hypercapnia induced by ventilating the animals with a gas mixture containing 10% CO(2), or 3) hyperventilation with resultant hypocapnia. Under these conditions, the concentrations of 6-keto-PGF(1alpha) in the CSF were measured in five experimental animals and six controls. In summary, the dexamethasone pretreatment 1) attenuated the hypercapnia-induced dilator responses of pial arterioles and prevented the hypercapnia-associated fall in mean arterial blood pressure; 2) caused moderate, although not statistically significant, diminution in 6-keto-PGF(1alpha) levels in the CSF during baseline; 3) blocked hypercapnia-induced elevation of 6-keto-PGF(1alpha); and 4) enhanced vasoconstrictive arteriolar responses to hyperventilation. We speculate that in the clinical setting, the dexamethasone effects may compromise the adjustments of global or regional cerebral blood flow to changing physiologic states in neonates.
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PMID:Dexamethasone pretreatment attenuates cerebral vasodilative responses to hypercapnia and augments vasoconstrictive responses to hyperventilation in newborn pigs. 1253 84

Hormonal changes during early neonatal life play a major role in the physiological processes underlying the maturation of several organs. Since prostaglandins and cortisol are associated with fetal organ system maturation, the aim of this study was to evaluate 15-ketodihydro-PGF(2alpha) (PGM) and cortisol plasma concentrations during the first 21 days after birth in foals born by either spontaneous (24 foals) or low-dose oxytocin (OT)-induced parturition performed after at least 320 gestational days (25 foals) since induction is often considered to be a cause of prematurity. After spontaneous birth, the PGM concentration was significantly (P<0.05) higher at 20 and 30min compared to samples taken several hours or days later, while induced foals showed significantly (P<0.05) higher concentrations at 10, 20, and 30min. Regarding differences between the two groups, the plasma concentration of PGM was significantly higher 10 (P<0.01), 20 (P<0.05), and 30 (P<0.05)min and 3h (P<0.05) after birth in induced foals compared to foals born by spontaneous parturition. It is difficult to determine whether the higher initial PGM concentrations in induced foals is related to higher uterine or fetal PGM release induced by exogenous OT stimulation. Cortisol plasma levels in both groups were higher at birth (P<0.05) compared to the later sampling times. No differences were observed between the two groups indicating that the induction protocol used does not seem to result in premature foals.
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PMID:15-Ketodihydro-PGF2alpha and cortisol plasma concentrations in newborn foals after spontaneous or oxytocin-induced parturition. 1900 88