leukotriene-b4 and Chorioamnionitis

Spontaneous preterm labor remains a significant cause of high morbidity and mortality in the newborn. Chorioamnionitis with an associated rise in prostaglandins (PGs) is thought to be one of the factors responsible for the onset of preterm labor. In this study, 52 placentas and membranes from gestations of 35 weeks' or fewer were collected. Tissue samples of membranes and placentas were incubated in pseudoamniotic fluid, and the levels of PGs and leukotriene B4 were assayed. Swallowed amniotic fluid aspirated from the infants' stomachs was analyzed for PGs and examined microscopically for the presence of degenerate neutrophilic polymorphonuclear leukocytes (pus cells) and bacterial organisms. Prostaglandins E and F and leukotriene B4 production were significantly higher in the membranes and placentas with chorioamnionitis than in those without. Although the comparison of PG levels in the gastric fluid of infants with and without chorioamnionitis did not reach statistical significance, there was a trend toward higher levels of PGs with chorioamnionitis. Prostaglandin E levels from membranes and placentas and PGF from placentas were significantly elevated in the gastric fluid of infants with pus cells and organisms. These findings support the hypothesis that chorioamnionitis may initiate preterm labor.

Topics: Chorioamnionitis; Extraembryonic Membranes; Female; Gastric Juice; Humans; Leukotriene B4; Obstetric Labor, Premature; Placenta; Pregnancy; Prostaglandins; Prostaglandins E; Prostaglandins F

The production of leukotriene B4 (LTB4) by the human placenta in vitro was measured by radioimmunoassay. In early pregnancy (7-12 weeks gestation) LTB4 production rate (pmol/mg dry weight/2 h) was 3.7 (2.6-4.7) (median and range; n = 9) and at term it was 0.7 (0.4-2.3; n = 10) in placental tissue obtained at elective caesarean section, and 2.7 (1.3-3.6; n = 10) in samples following labour of spontaneous onset and vaginal delivery. In spontaneous preterm labour (26-36 weeks gestation) with normal placental histology LTB4 production was 0.7 (0.3-1.7; n = 14), but it was significantly higher in preterm placentas with inflammatory infiltration: 3.1 (0.8-4.8; n = 6). These data show that the production of LTB4 by human placenta is high in early pregnancy, but remains low during the third trimester, with a significant increase in spontaneous labour at term. LTB4 output is low in uncomplicated preterm labour but markedly increased in chorioamnionitis-associated preterm labour.

Topics: Adolescent; Adult; Chorioamnionitis; Female; Humans; Leukotriene B4; Obstetric Labor, Premature; Placenta; Pregnancy; Pregnancy Trimester, First; Pregnancy Trimester, Third

The production of prostaglandin E (PGE) and leukotriene B4 (LTB4) by amnion was measured in vitro in 12 women delivered after spontaneous preterm labour and in 15 women delivered after spontaneous labour at term. The placenta and fetal membranes were examined histologically in all cases. PGE output (fmol/mg dry weight/2 h) in the amnions from uncomplicated preterm deliveries was low (median 486, range 232-3203, n = 7) compared with the values obtained after spontaneous labour at term (5529, 1722-14,226, n = 15). In amnions from preterm deliveries complicated by acute chorioamnionitis or round cell infiltration there was massive release of PGE (15,262, 10,905-27,640, n = 5) which was accompanied by an increase in LTB4 production. Inflammatory infiltration of the fetal membranes results in a huge increase in PG production which could cause preterm labour.

Topics: Amnion; Chorioamnionitis; Female; Humans; Leukotriene B4; Obstetric Labor, Premature; Pregnancy; Prostaglandins E