Ultrasonographic and Biochemical Markers of Preterm Labor

> At present preterm delivery is the leading cause of perinatal morbidity and mortality and its incidence is remained stable during the past 10 years. Conventional methods of identifying patients at risk of preterm delivery such as obstetrics history, demographic factors or evaluation of uterine contractions and cervix by digital examination show disappointintly low sensitivity and positive predictive value. In this review we describe new ultrasonographic and biochemical approaches that have been recently proposed to screen for preterm labor both in patients with intact and with premature rupture of the membranes. The ultrasonographic detection of a short uterine cervix and/or of a dilation of the internal os, expression of weakening of the lower uterine segment or cervical ripening, seems to efficiently predict patients at risk of preterm delivery. The efficiency of this marker may be improved by the association with the assay of fetal fibronectin or pro inflammatory cytokines (interleukin-6 and interleukin-8) in cervical secretions. Further by the concentrations of interleukin-6 and interleukin-8 in cervical secretions seems to be possible to predict among patients in preterm labor those secondary to subclinical endoamniotic infection or chorioamnionitis. The use of these new markers in the future may allow a better identification of patients at risk of preterm labor and a proper selection of the treatment (medical or surgical) required for such patients.     

The neuronal alpha6 subunit forms functional heteromeric acetylcholine receptors in human transfected cells

OBJECTIVE: Our purpose was to create a model for predicting amnionitis and rapid delivery in preterm labor patients by use of amniotic fluid interleukin-6 and clinical parameters. STUDY DESIGN: Amniotic fluid was cultured and analyzed, and a clinical score (incorporating gestational age, amniotic fluid Gram stain, glucose, leukocyte esterase, and maternal serum C-reactive protein) was determined in 111 patients diagnosed with preterm labor. Statistical analysis involved t tests, chi2, logarithmic regression, and multivariate regression analysis (P < or = .05). RESULTS: The incidence of positive amniotic fluid cultures was 8.7% (9 of 103 patients). Patients with positive cultures of the amniotic fluid had a shorter delivery interval (4.8 +/- 7.5 vs 28.9 +/- 25.4 days, P < .001). Patients with elevated amniotic fluid interleukin-6 (> or = 7586 pg/ml) were more likely to have a positive amniotic fluid culture (relative risk = 8.8, 95% confidence interval = 1.6 to 47.4, P < .001) and to be delivered within 2 days (relative risk = 16.8, 95% confidence interval = 4.5 to 62.7, P < .001). Stepwise multivariate regression analysis yielded a model using interleukin-6, cervical dilatation, and gestational age (r2 = 0.63, P < .001) with a specificity of 100% for predicting delivery within 2 days of amniocentesis. CONCLUSIONS: A mathematical model using maternal amniotic fluid interleukin-6 seems to be a useful clinical tool for quantifying the interval to preterm birth for patients in preterm labor.     

Intraamniotic infection in patients with preterm labor and twin pregnancies

BACKGROUND: Microbial invasion of the amniotic cavity plays a major role in the pathogenesis of preterm labor and delivery in singleton pregnancy. Nevertheless, this association is not well established among patients with multiple gestations. The purpose of our study was to explore the role of intraamniotic infection in the setting of twin pregnancies. METHODS: Consecutive women with twin gestations, intact membranes and preterm labor who underwent transabdominal amniocentesis under sonographic guidance. Amniotic fluid (AF) was retrieved from both sacs and cultured for aerobic and anaerobic microorganisms as well as for Mycoplasma species. Intraamniotic infection was defined as a positive AF culture for microorganisms. Mann Whitney U test or Student t-test or Fisher's exact test were utilized for analysis. RESULTS: Amniotic fluid was obtained from 74 patients. Sixty-eight women delivered prematurely (91.9%). Amniotic fluid culture results were positive for microorganisms in nine cases and all women with intraamniotic infection delivered prematurely as well as 59 (90.7%) patients with negative culture. Among the nine patients with intraamniotic infection, microorganisms were isolated from the presenting sac in five cases (55.6%), from both sacs in three patients (33.3%) and from the upper sac in the remaining case (11.1%). Patients with a positive AF culture had a more advanced cervical dilatation, a shorter interval amniocentesis-to-delivery and a higher incidence of clinical chorioamnionitis than those with a negative AF culture. CONCLUSIONS: The prevalence of intraamniotic infection and clinical and histological chorioamnionitis in twin pregnancies and preterm labor is similar to singleton pregnancies and preterm labor. Therefore, women with multiple gestations and preterm labor should be managed as singleton pregnancies.     

The natural interleukin-1 receptor antagonist in the fetal, maternal, and amniotic fluid compartments: the effect of gestational age, fetal gender, and intrauterine infection

OBJECTIVES: The interleukin-1 receptor antagonist is a newly discovered cytokine that blocks the biologic effects of interleukin-1 in vitro and in vivo. This cytokine is a physiologic component of amniotic fluid and is considered to be of critical importance in the homeostasis of the cytokine network. This study was undertaken to systematically examine the bioavailability of interleukin-1 receptor antagonist in the maternal, fetal, and amniotic fluid compartments during term and preterm parturition in women with and without microbial invasion of the amniotic cavity. STUDY DESIGN: The patient population consisted of (1) pregnant women in the midtrimester (n = 42), (2) patients who underwent cordocentesis for diagnostic purposes (n = 39), (3) patients with preterm labor (n = 126), (4) women with term gestation (n = 102), and (5) healthy nonpregnant women (n = 8). Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as Mycoplasma sp. Interleukin-1 receptor antagonist concentrations were determined by enzyme-linked immunoassay in maternal and fetal plasma, amniotic fluid, and neonatal urine. Microbial invasion of the amniotic cavity was defined as the presence of a positive amniotic fluid culture for microorganisms. RESULTS: (1) Interleukin-1 receptor antagonist was normally present in fetal plasma samples obtained by cordocentesis, and its concentration increased with advancing gestational age (n = 39; r = 0.61, p < 0.001). (2) Patients at term not in labor had higher amniotic fluid interleukin-1 receptor antagonist concentrations than patients in the midtrimester (median 40.1 ng/ml, range 5.7 to 213.1 vs median 16.2 ng/ml, range 3.2 to 62.2, respectively, p < 0.001). (3) Amniotic fluid and cord plasma interleukin-1 receptor antagonist concentrations were significantly higher in patients with preterm labor and microbial invasion of the amniotic cavity than in those without microbial invasion of the amniotic cavity (amniotic fluid: median 219.9 ng/ml, range 35.4 to 504 vs median 80.6 ng/ml, range 24.3 to 399, respectively, p < 0.001; umbilical cord plasma: median 4.8 ng/ml, range 0.3 to 167.0 vs median 1.0 ng/ml, range 0 to 276.0, respectively, p < 0.05). In contrast, these differences were not found in patients with term labor either with or without microbial invasion of the amniotic cavity. (4) In both term and preterm patients the amniotic fluid and neonatal urine concentrations of interleukin-1 receptor antagonist were significantly higher in female fetuses than in male fetuses (amniotic fluid, preterm: median 191.9 ng/ml, range 51.6 to 504.0 vs median 61.1 ng/ml, range 11.5 to 284.9, respectively, p < 0.001; amniotic fluid, term: median 58.7 ng/ml, range 25.5 to 264.0 vs median 33.9 ng/ml, range 3.4 to 132.4, respectively, p < 0.001; neonatal urine: median 317 ng/ml, range 59.0 to 440.8 vs median 12.2 ng/ml, range 2.5 to 61.6, respectively, p < 0.005). CONCLUSIONS: (1) Interleukin-1 receptor antagonist is physiologically present in the fetal, maternal, and amniotic fluid compartments; (2) microbial invasion of the amniotic cavity in the preterm gestation is associated with a significant increase in the concentrations of this cytokine in the fetal and amniotic fluid compartments but not in maternal plasma; (3) fetal urine is a source of amniotic fluid interleukin-1 receptor antagonist; (4) fetal plasma interleukin-1 receptor antagonist concentrations increase with gestational age; (5) there is a significant effect of fetal gender in amniotic fluid and neonatal urine concentrations of interleukin-1 receptor antagonist.     

Placental histopathology in premature rupture of membranes. Its relationship with microbiological findings, maternal, and neonatal outcome

BACKGROUND: There is a close relationship between premature membrane rupture, bacterial infections and premature labor. AIM: To study placental histological changes in patients with preterm membrane rupture. To establish a relationship between pathological findings, amniotic fluid and lower genital tract microbiological studies, maternal and neonatal outcome. PATIENTS AND METHODS: Patients with premature membrane rupture of membranes between 24 and 34 weeks of gestation participated in this study. On admission, patients had no evidence of clinical chorioamnionitis, labor or fetal distress. Microbiological studies of the amniotic fluid and cervicovaginal secretions were performed and the placenta was sent for pathological study. RESULTS: Seventy one placentas were available for the study. The main pathological findings were acute chorioamnionitis in 58%, trophoblastic proliferation in 38%, funisitis in 37%, villitis in 16%, fetal vascular lesions in 14% and no findings in 17%. Microbial invasion of amniotic cavity was present in 89% of acute chorioamnionitis. Sixty one percent of trophoblastic proliferation and all fetal vascular lesions were associated with negative amniotic and cervical cultures. Newborns with acute funisitis had a higher frequency of neonatal death (29%), severe asphyxia (42%) and neonatal infections (29%). CONCLUSIONS: Acute chorioamnionitis is the most frequent finding in patients with preterm membrane rupture and microbial invasion of amniotic cavity. In the absence of intra amniotic infection, proliferation of the trophoblast and the presence of fetal vascular lesions predominate. Acute funisitis is strongly associated with adverse fetal outcome.     

The value of amniotic fluid interleukin-6, white blood cell count, and gram stain in the diagnosis of microbial invasion of the amniotic cavity in patients at term

PROBLEM: Subclinical microbial invasion of the amniotic cavity occurs in 18.8% of women with term labor and intact membranes and in 34% of patients with term PROM and is a risk factor for the development of puerperal infection related morbidity. Although amniotic fluid white blood cell count, interleukin-6 determination, and Gram stain examination have been used for the diagnosis of intrauterine infection in patients with preterm labor and preterm premature rupture of membranes, no information is available about the accuracy and specific cut-off values for these tests in patients at term. The purpose of this study was to compare the performance of the amniotic fluid Gram stain examination, white blood cell count, and interleukin-6 determination in the identification of microbial invasion of the amniotic cavity in patients at term with and without PROM. METHOD: Amniotic fluid was retrieved from 148 patients with term gestations (90 patients with spontaneous labor and intact membranes and 58 patients with PROM). Samples were cultured for bacteria and Mycoplasma species. Amniotic fluid Gram stain, white blood cell count, and interleukin-6 determinations (ELISA, sensitivity: 43 pg/ml) were performed in all samples. Microbial invasion of the amniotic cavity was defined as a positive amniotic fluid culture for microorganisms. Analysis was conducted using Mann-Whitney U test, Fisher's exact test, receiver operating characteristic curves and logistic regression. RESULTS: Patients with spontaneous labor and intact membranes: The prevalence of microbial invasion of amniotic cavity in this group was 15.6% (14/90). The most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determination (sensitivity for: interleukin-6 > or = 5.7 ng/ml = 86%, white blood cell count > or = 20 cells/mm3 = 64%, Gram stain = 28%). The most specific test was the Gram stain of the amniotic fluid (specificity for: Gram stain = 84%, interleukin-6 = 79% and white blood cell count = 63%). Multiple logistic regression demonstrated that amniotic fluid interleukin-6 concentration was the only covariate that retained statistical significance when intrauterine infection was used as outcome variable. Patients with PROM: The prevalence of a positive amniotic fluid culture in this group was 39.7% (23/58). Logistic regression demonstrated that only interleukin-6 retained a significant relationship with the results of amniotic culture when all variables were entered simultaneously into a model to predict amniotic fluid culture results. The most sensitive tests for the detection of intrauterine infection were interleukin-6 determination and white blood cell count (sensitivity for interleukin-6 > or = 3.4 ng/ml and white blood cell count > or = 20 cells/mm3 = 69.6% for both). The most specific test was Gram stain (97.1%). CONCLUSIONS: Amniotic fluid interleukin-6 determination is the best rapid test for the detection of microbial invasion of the amniotic cavity in patients at term with and without PROM. When this test is not available, amniotic fluid Gram stain and white blood cell count represent valid diagnostic tools to assess the microbial state of amniotic cavity.     

Evidence of participation of the soluble tumor necrosis factor receptor I in the host response to intrauterine infection in preterm labor

PROBLEM: This study was conducted to determine whether: (1) the soluble tumor necrosis factor receptor I (sTNF-rI) is present in human amniotic fluid, neonatal urine, and the feto-maternal plasma; (2) there are changes in the concentration of the sTNF-rI in amniotic fluid with gestational age; and (3) microbial invasion of the amniotic cavity (in term and preterm parturition) is associated with changes in amniotic fluid sTNF-rI concentrations. METHOD: Amniotic fluid was retrieved by amniocentesis from 185 women classified into 11 groups according to gestational age (midtrimester, preterm gestation, and term), the presence or absence of labor, spontaneous rupture of membranes and microbial invasion of the amniotic cavity. sTNF-rI was assayed with a sensitive and enzyme-linked immunosorbent assay (ELISA) validated for amniotic fluid. In addition, sTNF-rI concentrations were determined in fetal blood obtained by cordocentesis in preterm gestations (N = 24) or at the time of delivery after spontaneous labor at term (N = 10). sTNF-rI concentrations were also measured in maternal venous and cord blood and neonatal urine (n = 13). RESULTS: sTNF-rI was found to be present in all amniotic fluid samples, maternal blood and fetal blood and neonatal urine samples; sTNF-rI concentrations were higher in the midtrimester than at term (mean +/- SD: 36.2 +/- 12.2 ng/ml versus mean +/- SD: 5.56 +/- 5.72 ng/ml [P < .05]); patients with preterm labor and microbial invasion of the amniotic cavity (with intact or with ruptured membranes) had significantly higher amniotic fluid concentrations of sTNF-rI than patients without microbial invasion; in the absence of microbial invasion, parturition (both term and preterm) was not associated with changes in amniotic fluid concentrations of sTNF-rI; neonatal urine contained the highest concentrations of sTNF-rI of all biological fluids assayed including maternal and neonatal/fetal blood and amniotic fluid. CONCLUSIONS: It was concluded that sTNF-rI is a physiologic constituent of amniotic fluid, as well as of the fetal and maternal plasma; that amniotic fluid sTNF-rI concentrations decrease as a function of gestional age and increases in the concentration of the sTNF-rI are part of the host response to intrauterine infection in preterm parturition.     

Amniotic fluid cytokines (interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8) and the risk for the development of bronchopulmonary dysplasia

OBJECTIVE: Our purpose was to test the hypothesis that neonates who develop bronchopulmonary dysplasia have higher amniotic fluid concentrations of proinflammatory cytokines than those who do not develop bronchopulmonary dysplasia. STUDY DESIGN: The relationship between amniotic fluid concentrations of interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8 and the occurrence of bronchopulmonary dysplasia in the neonate was examined in 69 patients who were delivered of preterm neonates (< or = 33 weeks) within 5 days of amniocentesis. Cytokines were measured by specific immunoassays. RESULTS: Bronchopulmonary dysplasia was diagnosed in 19% (13/69) of newborns. Median amniotic fluid concentrations of interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8 concentrations were significantly higher in mothers whose infants had bronchopulmonary dysplasia than in mothers whose infants did not have bronchopulmonary dysplasia (p < 0.05 for each). Neonates who had bronchopulmonary dysplasia were delivered at earlier gestational ages and had lower birth weights than those without bronchopulmonary dysplasia. The differences in median amniotic fluid interleukin-6, interleukin-1 beta, and interleukin-8 between these two groups remained significant after we adjusted for the effect of gestational age at birth (p < 0.05 for each). CONCLUSIONS: (1) Antenatal exposure to proinflammatory cytokines is a risk factor for the development of bronchopulmonary dysplasia; (2) the injury responsible for bronchopulmonary dysplasia in a subset of neonates may begin before birth.     

The fast-reacting fetal fibronectin test: a screening method for better prediction of the time of delivery

OBJECTIVE: Our aim was to determine from what time onward fetal fibronectin is consistently detectable in the cervicovaginal secretions before delivery and to what extent the actual time of delivery can be better determined by this procedure than by the sole use of the Bishop score. STUDY DESIGN: A fast-reacting fetal fibronectin test was performed on 206 women on their expected date of confinement. In addition, the cervical status was evaluated with use of a modified Bishop score. Follow-up evaluations were subsequently carried out in the course of the routine examinations. RESULTS: Women with a positive fetal fibronectin test result and a high Bishop score were delivered after a median of 1.7 days. Conversely, women with a negative fetal fibronectin test result and a low Bishop score were delivered after a median of 7.1 days. CONCLUSION: Determination of fetal fibronectin in combination with the Bishop score makes it possible to predict the actual time of delivery with a greater degree of accuracy.     

The role of amniotic fluid L-selectin, GRO-alpha, and interleukin-8 in the pathogenesis of intraamniotic infection

OBJECTIVE: Our purpose was to compare and correlate amniotic fluid GRO-alpha, interleukin-8, and L-selectin in patients with and without intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 45 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection, and 31 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid tests for Gram stain, glucose, neutrophil counts, creatinine, pH, and specific gravity were performed. Amniotic fluid levels of soluble L-selectin, interleukin-8, and GRO-alpha were measured by an enzyme-linked immunoassay and normalized by amniotic fluid creatinine levels. The Mann-Whitney Utest and Spearman's rank correlation test were used for statistical analyses. RESULTS: Amniotic fluid median levels of soluble L-selectin, interleukin-8, and GRO-alpha were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (soluble L-selectin: median 3334.6 ng/mg creatinine, range 408.4 to 15,956.8 vs 717.2 ng/mg creatinine, range 129.4 to 4601.9, p = 0.009; GRO-alpha: median 841.6 ng/mg creatinine, range 28.1 to 8591.7 vs 56.8 ng/mg creatinine, range 0.0 to 440.2, p < 0.0001; interleukin-8: median 4932.7 ng/mg creatinine, range 0.0 to 55,058.7 vs 28.3 ng/mg creatinine, range 0.0 to 1161.6, p = 0.0004). Patients with intraamniotic infection had significantly higher amniotic fluid leukocyte counts and leukocyte esterase activities and significantly lower amniotic fluid glucose concentrations compared with those without intraamniotic infection. Amniotic fluid GRO-alpha, interleukin-8, and soluble L-selectin were positively correlated, and each was positively correlated with amniotic fluid leukocytes and negatively correlated with amniotic fluid levels of glucose. CONCLUSIONS: Our data indicate amniotic fluid GRO-alpha and interleukin-8 may be two potent leukocyte chemoattractants and activators, and L-selectin is rapidly shed from leukocytes in the amniotic fluid in patients with intraamniotic infection.     

What use are fibromyalgia control points?

OBJECTIVE: Our purpose was to determine whether early second-trimester amniotic fluid interleukin-6 levels predict delivery before 34 weeks' gestation. STUDY DESIGN: We used stored second-trimester amniotic fluid samples obtained from women undergoing genetic amniocentesis from 1988 to 1996. Interleukin-6 levels were measured by enzyme-linked immunosorbent assay in samples from every case known to result in delivery from 20 to 34 weeks' gestation (n = 290), and 290 matched controls delivering at > or =37 weeks. Fetal aneuploidies, anomalies, and all cases delivering within 30 days of the amniocentesis (which were thought to be possibly procedure related) were excluded. RESULTS: Interleukin-6 levels were higher in cases than controls (1.9 +/- 5.2 vs 1.0 +/- 2.4 ng/ml, p = 0.004). Cases were grouped according to whether the preterm delivery was indicated or spontaneous: The mean interleukin-6 levels were significantly higher than controls in the spontaneous group (1.6 +/- 3.2 vs 0.8 +/- 1.2 ng/ml, p = 0.01) but not in the indicated group (1.4 +/- 4.0 vs 0.8 +/- 1.2 ng/ml, p = 0.12). In all samples the interleukin-6 level was negatively correlated with the gestational age at delivery (R = -0.11633, p = 0.007). CONCLUSION: Elevated early second-trimester amniotic fluid interleukin-6 levels are associated with preterm delivery, confirming that in some women this indicator of very early intrauterine inflammation predicts birth before 34 weeks' gestation.     

A comparison of rapid amniotic fluid markers in the prediction of microbial invasion of the uterine cavity and preterm delivery

OBJECTIVE: The purpose of this study was to evaluate amniotic fluid lactate dehydrogenase level in comparison with other rapid markers in prediction of microbial invasion of the uterine cavity and preterm delivery < or = 36 hours after amniocentesis. STUDY DESIGN: One hundred thirty-one women in preterm labor with intact membranes underwent transabdominal amniocentesis. Amniotic fluid was analyzed for leukocyte count, glucose level, lactate dehydrogenase level, and Gram stain. Cultures for aerobes, anaerobes, and Mycoplasma sp. were performed. Amniocentesis-to-delivery interval was calculated. The study group was divided and the findings compared according to amniotic fluid culture results and according to amniocentesis-to-delivery interval. Sensitivity, specificity, and positive and negative predictive value were calculated for lactate dehydrogenase, leukocyte count, glucose, and Gram stain in the prediction of positive amniotic fluid culture and preterm delivery < or = 36 hours after amniocentesis. Receiver-operator characteristic curve analysis, logistic regression analysis, t tests, and nonparametric tests were used. RESULTS: The prevalence of positive amniotic fluid cultures was 12% (16 of 131). The median lactate dehydrogenase level (1084 U/L) was significantly greater for women with a positive amniotic fluid culture than for those with a negative culture (median lactate dehydrogenase level 194 U/L; p < 0.0002). The critical values calculated for optimal performance in prediction of a positive amniotic fluid culture were a lactate dehydrogenase level > or = 419 U/L, leukocyte count > or = 50 cells/mm3 (50 x 10(6)/L) and glucose < or = 17 mg/dl (0.94 mmol/L). Lactate dehydrogenase, leukocyte count, glucose, and Gram stain were equally sensitive and specific in prediction of a positive amniotic fluid culture. Thirty-nine women (29.8%) gave birth < or = 36 hours after amniocentesis. The median lactate dehydrogenase level (414 U/L) was significantly greater among women giving birth < or = 36 hours after amniocentesis than among women giving birth > 36 hours after amniocentesis (median lactate dehydrogenase, 173 U/L; p < 0.001). Critical values of lactate dehydrogenase > or = 225 U/L, leukocyte count > or = 10 cells/mm3 (10 x 10(6)/L) and glucose < or = 34 mg/dl (1.9 mmol/L) were selected for optimal performance in prediction of amniocentesis-to-delivery interval < or = 36 hours. Lactate dehydrogenase level had the best sensitivity (74%) in prediction of delivery < or = 36 hours after amniocentesis in contrast to leukocyte count (49%), glucose (62%), and positive Gram stain (26%). Amniotic fluid lactate dehydrogenase values > or = 225 U/L were associated with a fivefold greater risk for delivery < or = 36 hours after amniocentesis (odds ratio 5.46, 95% confidence interval 2.00 to 14.87; p = 0.0006). CONCLUSION: Amniotic fluid lactate dehydrogenase level has diagnostic value in prediction of a positive amniotic fluid culture and delivery < or = 36 hours after amniocentesis. Lactate dehydrogenase is a readily available, inexpensive, rapid amniotic fluid marker that can be measured in any hospital laboratory.     

An increase in fetal plasma cortisol but not dehydroepiandrosterone sulfate is followed by the onset of preterm labor in patients with preterm premature rupture of the membranes

OBJECTIVE: The role of steroid hormones in the control of human parturition has been a subject of debate. Activation of the fetal hypothalamic-pituitary-adrenal axis leading to an increase in plasma cortisol is followed by the onset of parturition in sheep. In contrast, androgens, specifically, dehydroepiandrosterone sulfate, have been implicated in the control of parturition in nonhuman primates. The purpose of this study was to determine the relationship between human fetal plasma cortisol and dehydroepiandrosterone sulfate and the onset of preterm labor in patients with preterm premature rupture of the membranes. STUDY DESIGN: Fetal blood sampling was performed in 51 patients with preterm premature rupture of membranes who were not in labor on admission. Amniotic fluid was cultured for aerobic and anaerobic bacteria and mycoplasmas. Corticosteroids had not been administered before fetal blood sampling. Cortisol and dehydroepiandrosterone sulfate were measured with sensitive and specific immunoassays. Analysis was conducted with nonparametric statistics and survival analysis. RESULTS: (1) Patients who went into spontaneous labor and delivered within 7 days of cordocentesis had a significantly higher median level of fetal plasma cortisol but not of dehydroepiandrosterone sulfate than those delivered after 7 days (for fetal plasma cortisol: median 8.35 [4.7 to 12.4] micrograms/dL vs median 4.75 [3.0 to 10.4] micrograms/dL, P <.0001; for fetal plasma dehydroepiandrosterone sulfate: median 154.4 [8.6 to 333.8] micrograms/dL vs median 194.6 [96.7 to 402.5] micrograms/dL, P =.09). (2) The cordocentesis-to-delivery interval was significantly shorter in patients with a fetal plasma cortisol value of >/=7 micrograms/dL (derived by receiver-operating characteristic curve analysis) than in those with fetal cortisol <7 micrograms/dL (median 49 [4 to 1849] hours vs median 325 [11 to 2590] hours, P <.001). (3) Fetal plasma cortisol, but not maternal cortisol, was an independent predictor of the duration of pregnancy after we adjusted for gestational age and the results of amniotic fluid culture (hazards ratio 2.9, P <.05). (4) There was a significant correlation between fetal plasma cortisol and fetal plasma interleukin-6 (r = 0.3, P <.05). (5) A strong relationship was found between the fetal plasma cortisol/dehydroepiandrosterone sulfate ratio and the interval to delivery (P <.005). CONCLUSION: An elevation in fetal plasma cortisol but not dehydroepiandrosterone sulfate was followed by the onset of spontaneous preterm labor in patients with preterm premature rupture of the membranes.     

Inflammatory cytokine (interleukins 1, 6 and 8 and tumor necrosis factor-alpha) release from cultured human fetal membranes in response to endotoxic lipopolysaccharide mirrors amniotic fluid concentrations

OBJECTIVE: This study was conducted to quantitate and compare the amount of cytokines released from human fetal membranes in response to treatment with bacterial lipopolysaccharide and to compare this with amniotic fluid levels. STUDY DESIGN: Amniochorionic membranes were collected from women undergoing elective repeat cesarean section and showing no signs of infection- or pregnancy-related complications. Membranes were maintained in an organ explant system and stimulated with bacterial lipopolysaccharide for 24 hours. Media samples were collected and stored at -20 degrees C until cytokine levels were assayed by enzyme-linked immunosorbent assay. RESULTS: Enzyme-linked immunosorbent assay results demonstrated that lipopolysaccharide stimulated production of interleukins 1, 6 and 8 and tumor necrosis factor-alpha by the fetal membranes in comparison with the control cultures. A greater release of interleukin-6 and interleukin-8 compared with interleukin-1 and tumor necrosis factor-alpha was noticed. The relationships between cytokine concentrations observed in culture mirror those seen in amniotic fluid. CONCLUSION: Amniochorionic membranes can respond to an infectious process with increased secretion of interleukins 1, 6 and 8 and tumor necrosis factor-alpha. Cytokines produced from both amnion and chorion (interleukin-6 and interleukin-8) are released in greater quantities than those cytokines produced from chorion or amnion alone (interleukin-1 and tumor necrosis factor-alpha). These studies support a major role for amnion in infection-induced preterm labor.     

Choriodecidual inflammation: a potentially preventable cause of perinatal HIV-1 transmission?

The obstetric risk factors for perinatal transmission of HIV-1 include preterm birth, prolonged rupture of the chorioamniotic membranes, and clinical and histological bacterial chorioamnionitis. A chronic chorioamnionitis precedes many cases of preterm labour and spontaneous rupture of membranes, whereas an acute chorioamnionitis is more common after rupture of the membranes at term. Amniotic fluid cytokines are raised in the presence of term and preterm intrauterine bacterial infections, and various cytokines seem able to attract HIV-1-infected leucocytes into the amniotic cavity and to increase replication of HIV-1. We postulate that the association of preterm birth and prolonged rupture of membranes with perinatal transmission of HIV-1 may result from an associated chronic or acute bacterial chorioamnionitis marked by the migration of HIV-1-infected maternal leucocytes into the amniotic cavity. Antibiotic treatment could prevent this sequence of events.     

Activin A and inhibin B in extra-embryonic coelomic and amniotic fluids, and maternal serum in early pregnancy

Activin A and inhibin B levels were measured, using a two-site enzyme immunoassay, in extra-embryonic coelomic fluid, amniotic fluid and maternal serum samples retrieved from 23 healthy pregnant women, at 8 (n=8), 9 (n=8), and 10 (n=7) weeks of gestation. Dimeric activin A and inhibin B were measurable in all samples. Median (+/-SEM) activin A concentrations in coelomic fluid (0.98+/-0.34 ng/ml) were significantly higher than in maternal serum (0.68+/-0.05 ng/ml) and in amniotic fluid (0.09+/-0.04 ng/ml) (P<0.05). Maternal serum activin A levels were significantly higher than amniotic fluid concentrations. Median (+/-SEM) inhibin B concentrations in coelomic fluid (24.32+/-6.02 pg/ml) were significantly higher than in maternal serum (5.94+/-0.97 pg/ml) and in amniotic fluid (6.31+/-1.53 pg/ml) (P<0.05), while no significant difference between maternal serum levels and amniotic fluid concentrations was found. No significant difference in activin A and inhibin B levels in extra-coelomic fluid, amniotic fluid, and maternal serum throughout the 3 weeks of pregnancy was found. The present study showed that coelomic fluid is an important reservoir of activin A and inhibin B, supporting the hypothesis that the extra-embryonic coelom may have a secretory role during the first 11 weeks of gestation.     

Inhibition and augmentation of progesterone production during pregnancy: effects on parturition in rhesus monkeys

OBJECTIVES: Uterine quiescence during mammalian pregnancy is attributed to progesterone. However. systemic progesterone levels remain elevated in primates before parturition. Epostane, a selective 3beta-hydroxysteroid dehydrogenase inhibitor, and progesterone (with or without epostane) were administered to late pregnant rhesus monkeys to clarify the role of progesterone in primate parturition. STUDY DESIGN: On days 122 to 132 of gestation (term 167 days), 11 rhesus monkeys (Macaca mulatta) with timed pregnancies were divided into three treatment groups: (1) epostane alone (10 mg/kg subcutaneously), (2) epostane with progesterone subcutaneously in Silastic silicone rubber capsules, and (3) progesterone implants only with no surgical instrumentation. Maternal and fetal blood and amniotic fluid were sampled for progesterone, estrone, estradiol, cortisol, testosterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and amniotic fluid was sampled for prostaglandins E2 and F2alpha. Uterine activity was monitored continuously by electromyography and intraamniotic pressure. Cervical status was assessed by a modified Bishop's score. Production of prostaglandins E2 and F2alpha by amnion was determined by tissue superfusion. The group of three noninstrumented monkeys, which received only progesterone Silastic silicone rubber implants subcutaneously at 146 to 148 days, were observed until spontaneous vaginal delivery. RESULTS: Epostane reduced maternal and fetal progesterone levels by 75% and 50%, respectively, followed by increased uterine activity and cervical ripening within 24 hours and vaginal delivery within 48 hours. Amniotic fluid progesterone decreased to undetectable levels. Progesterone implants prevented the epostane-induced decrease in maternal and fetal progesterone levels and the associated myometrial and cervical changes until the implants were removed. Alterations in other steroid hormones were consistent with inhibition of 3beta-hydroxysteroid dehydrogenase. Amniotic prostaglandin E2 production was increased sixfold by epostane (p < 0.05) but did not reach the high levels normally seen at spontaneous parturition. Animals that received progesterone implants alone had markedly elevated circulating progesterone concentrations yet were delivered spontaneously at term (range 163 to 167 days). CONCLUSIONS: Progesterone withdrawal induces preterm labor and delivery (which can be blocked by progesterone substitution) but exogenous progesterone, even in substantial quantities, does not prevent parturition at term.     

Elevated amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in intra-amniotic infection

OBJECTIVE: The study's objective was to determine and correlate amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in patients with and without intra-amniotic infection. STUDY DESIGN: Amniocentesis was performed on 41 pregnant women with preterm contractions, labor, or premature rupture of membranes. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture result. Amniotic fluid tests for Gram stain, glucose, leukocyte counts, creatinine level, pH, and specific gravity were performed. Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were measured by an enzyme-linked immunoassay. Unlike in previous reports, cytokines were normalized by amniotic fluid creatinine levels. RESULTS: Fifteen patients had intra-amniotic infection and 26 did not. Amniotic fluid median levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were significantly higher in pregnant women with intra-amniotic infection than in those without intra-amniotic infection (leukemia inhibitory factor median 3912 pg/mg creatinine, range 0.0-199314, vs 56 pg/mg creatinine, range 0. 0-12148, P =.01; interleukin 6 median 2005 ng/mg creatinine, range 27-4071, vs 990 ng/mg creatinine, range 7.5-3409, P =.005; interleukin 8: median 4933 ng/mg creatinine, range 0.0-55058, vs 61 ng/mg creatinine, range 0.0-2399, P =.005). Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were positively correlated. CONCLUSIONS: The data indicate that leukemia inhibitory factor plays an important role in the pathogenesis of intra-amniotic infection. In addition, significant elevations of and correlations among amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 suggest that measurements of these cytokines in amniotic fluid may be of diagnostic and prognostic importance.     

Sonographic evaluation of the uterine cervix

Ultrasonographic evaluation of the uterine cervix has been shown to help predict patients who may be at an increased risk for preterm delivery. The use of ultrasound in at-risk patients may improve the selection of those needing obstetric intervention, which therefore, may improve outcome and lower overall health care costs. Cervical competence, once thought to be a categorical variable, should now be thought of as a continuous variable, as the shortest cervical lengths are found in those women with a history of very early preterm delivery (> 24 weeks). Adjunctive tests, such as fetal fibronectin Bishop scoring and bacterial vaginosis may help to improve the accuracy of prediction of preterm birth; therefore a multifaceted risk approach to preterm birth is suggested in this article.     

DNA content and chromatin texture of benzo[a]pyrene-transformed human breast epithelial cells as assessed by image analysis

OBJECTIVE: To determine the relationship between the presence of Ureaplasma urealyticum in the amniotic cavity and adverse maternal and perinatal outcome in women with preterm labor. METHODS: Amniocentesis was performed in 181 patients with preterm labor and intact membranes. Amniotic fluid (AF) was cultured for aerobic and anaerobic bacteria and mycoplasmas. Patients were divided into three groups according to the results of AF culture: those with negative AF cultures (n=160), those with positive AF cultures and in whom the only microbial isolate was U urealyticum (n=11), and those with positive cultures for non-ureaplasmas or mixed microorganisms (n=10). Survival techniques were used for analysis. RESULTS: The prevalence of positive AF cultures in which the only microbial isolate was Uurealyticum was 6.1% (11 of 181), and of positive cultures with non-ureaplasmas or mixed microorganisms was 5.5% (10 of 181). The amniocentesis-to-delivery interval was significantly shorter in patients with positive cultures limited to U urealyticum than in those with negative cultures (median 7 [range 0.1-149] hours versus median 264 [0.1-2659] hours, P < .001). Preterm delivery within 48 hours, 72 hours, and 7 days was more frequent in patients with U urealyticum in the AF than in those with sterile AF (48 hour: 91% versus 33%; 72 hour: 91% versus 36%; 7 days: 100% versus 45%, P < .001 for each). Patients with positive AF cultures limited to U urealyticum had a significantly higher rate of adverse perinatal outcome than those with negative culture. Adverse outcomes included low gestational age at birth, low birth weight, histologic chorioamnionitis, significant neonatal morbidity, and perinatal death. CONCLUSION: Microbial invasion of the amniotic cavity with U urealyticum is a risk factor for impending preterm delivery and adverse perinatal outcome.