Pathogenesis of preterm labor and preterm premature rupture of membranes associated with intraamniotic infection

Behavioral perinatology: biobehavioral processes in human fetal development

Behavioral perinatology is as an interdisciplinary area of research that involves conceptualization of theoretical models and conduct of empirical studies of the dynamic time-, place-, and context-dependent interplay between biological and behavioral processes in fetal, neonatal, and infant life using an epigenetic framework of development. The biobehavioral processes of particular interest to our research group relate to the effects of maternal pre- and perinatal stress and maternal-placental-fetal stress physiology. We propose that behavioral perinatology research may have important implications for a better understanding of the processes that underlie or contribute to the risk of three sets of outcomes: prematurity, adverse neurodevelopment, and chronic degenerative diseases in adulthood. Based on our understanding of the ontogeny of human fetal development and the physiology of pregnancy and fetal development, we have articulated a neurobiological model of pre- and perinatal stress. Our model proposes that chronic maternal stress may exert a significant influence on fetal developmental outcomes. Maternal stress may act via one or more of three major physiological pathways: neuroendocrine, immune/inflammatory, and vascular. We further suggest that placental corticotropin-releasing hormone (CRH) may play a central role in coordinating the effects of endocrine, immune/inflammatory, and vascular processes on fetal developmental outcomes. Finally, we hypothesize that the effects of maternal stress are modulated by the nature, duration, and timing of occurrence of stress during gestation. In this paper, we elaborate on the conceptual and empirical basis for this model, highlight some relevant issues and questions, and make recommendations for future research in this area.

Protein kinase C stimulates release of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 by human decidual cells

OBJECTIVE

Increased concentrations of amniotic fluid matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)-1 have been observed in the context of premature rupture of membranes (PROM) and microbial invasion of the amniotic cavity. However, the source of the stimuli that contribute to the accumulation of these proteins in amniotic fluid remains to be identified. The present study was conducted to investigate MMP-2, MMP-9 and TIMP-1 secretion by decidual cells in response to activated protein kinase C (PKC).

METHODS

Decidual cells were isolated from term placentae, grown to confluence and incubated with control media or 10(-11) to 10(-8) mol/l concentrations of phorbol 12-myristate 13-acetate (PMA). Concentrations of MMP-2, MMP-9 and TIMP-1 in the culture supernatant were determined using sensitive and specific immunoassays. Substrate zymography was conducted to confirm MMP-9 assays.

RESULTS

PMA induced a concentration-dependent stimulation of release of MMP-9 (control vs. PMA l0(-9) and 10(-8) mol/l; p < 0.01) and TIMP-1 (control vs. PMA 10(-9) and 10(-8) mol/l; p < 0.001), but not MMP-2. A direct positive correlation was observed between MMP-9 and TIMP-1 release (r = 0.645; p < 0.001). Substrate zymography confirmed increased release of MMP-9 in response to PMA (control vs. PMA 10(-8) and PMA 10(-7) mol/l; p < 0.01).

CONCLUSIONS

Activation of PKC within the decidua will result in enhanced MMP-9 release, which upon activation could contribute to degradation of matrices within fetal membranes leading to PROM.

Cocaine use and preterm premature rupture of membranes: improvement in neonatal outcome

OBJECTIVE

Our aim was to determine whether cocaine use increases neonatal morbidity in patients with preterm premature rupture of membranes.

STUDY DESIGN

We reviewed records of pregnancies that were complicated with preterm premature rupture of membranes between 24 weeks to 34 weeks of gestation. Clinical characteristics and neonatal outcomes of patients who had positive results for cocaine in the urine were compared with patients with negative test results.

RESULTS

During the study period, 16.1% (85/528 patients) had a positive result in a urine screen for cocaine use. Patients who used cocaine were older and of higher gravidity and parity. When major neonatal morbidities were compared, there was improvement in morbidities that were linked to neonatal infection in patients with positive test results for cocaine, including pneumonia (3.5% vs 11.7%; P =.012) and sepsis (5.9% vs 14.7%; P =.016). Jointly, neonatal outcomes were significantly worse in the negative cocaine group (chi(2) = 5.143; P =.023).

CONCLUSION

The association of preterm premature rupture of membranes with major neonatal morbidity was unexpectedly and significantly weaker in pregnancies complicated by cocaine use.

Public health issues related to infection in pregnancy and cerebral palsy

Cerebral palsy is the most common neuromotor developmental disability of childhood, affecting as many as 8,000 to 12,000 children born in the U.S. each year (corresponding to a prevalence rate of between 2 and 3 per 1000 children). Recent improvements in neonatal care have not resulted in a decline in the overall prevalence of cerebral palsy and, in fact, greater numbers of very preterm/very low birth weight infants are surviving with cerebral palsy and other developmental problems. Infection in pregnancy may be an important cause of the disorder. In preterm infants, there appears to be about a 2-fold increased risk for cerebral palsy from chorioamnionitis, and in term infants the estimated increased risk is about 4-fold. Provisionally, chorioamnionitis might account for 12% of spastic cerebral palsy in term infants and 28% of cerebral palsy in preterm infants. Studies of biochemical markers of fetal inflammation typically associated with infection also suggest that an inflammatory response may be an important independent etiologic factor. If a substantial proportion of cerebral palsy is attributable to acute amnionitis infection and/or neonatal sepsis, cerebral palsy should have decreased in the United States after administration of intrapartum antibiotics became widespread in response to publication of public health consensus guidelines for Group B streptococcus in 1996. However, failure to detect declines could have a number of explanations and these explanations illustrate the many public health challenges related to intrauterine infection and cerebral palsy. Given the gaps in our current knowledge about intrauterine infection and cerebral palsy, public health recommendations for timely and specific prevention activities are limited at this time.

Cytokines of the placenta and extra-placental membranes: roles and regulation during human pregnancy and parturition

Summary In an earlier, companion, review, we concluded that cytokines produced by the placenta and associated membranes are likely to be involved in control of the processes of implantation and placental development (Bowen et al., 2002). In this review, we discuss evidence that cytokines continue to be part of a paracrine/autocrine regulatory network in the placenta and membranes throughout the mid and late stages of gestation. Cytokines are involved in regulation of placental growth during these later stages of pregnancy and also function to protect the fetus from pathological organisms. The evidence, while not entirely consistent, suggests that production of certain cytokines within the extraplacental membranes is altered during normal term parturition, whereas in the villous placenta evidence of labour-associated changes is much more equivocal. Roles for cytokines have been postulated in many facets of parturition, including expulsion of the fetus by uterine contractions, membrane rupture, and dilation of the cervix. Imbalances and disruptions to the cytokine milieu have been implicated in a number of diseases of pregnancy involving abnormalities of both placental growth/establishment and initiation of parturition. Cytokine secretion induced by intrauterine infection is associated with increased occurrence or severity of some neonatal diseases. This wealth of data supports the view that cytokines are an integral part of a functional regulatory/communication network operating within the placental-maternal unit during normal gestation.

Stillbirth: tissue findings with environmental and genetic links

This article discusses stillbirth from a pathologist's perspective. Stillbirth may be caused by many different mechanisms. There are specific maternal and fetal disorders leading to stillbirth, and some of these have genetic and environmental associations. Frequently, an autopsy examination may determine the specific cause of the fetal death. We illustrate tissue findings in stillbirth to put individual faces on this condition.

Intra-amniotic infection in patients with preterm prelabor rupture of membranes. Pathophysiology, detection, and management

The recent increase in knowledge about infection and preterm delivery has engendered many new questions and should make us rethink our long held beliefs and management strategies. Although this article focused primarily on infection as an important factor in the pathogenesis of PPROM, multiple other causes do exist. The various serologic and amniotic fluid assays that can identify activation of the host immune and inflammatory responses as a consequence of the microbial invasion of the amniotic cavity detailed in the preceding paragraphs are very promising but not yet available for clinical use. These tests identify the fetus in the early stages of an infectious process, before the full clinical manifestations of chorioamnionitis. Should such fetuses be treated with antibiotics in an effort to sterilize the amniotic cavity? Should patients with documented microbial invasion be delivered immediately or is there room for a more conservative management with aggressive antibiotic in utero treatment, altering the natural course of PPROM, avoiding extremely preterm deliveries? Certainly many questions remain unanswered. Continuing the search for information on the relationship between infection and PPROM can only add hope to one day finding an option for prevention, because many and probably most cases of PPROM are apparently caused by infection, and the opportunity for preventing this problem most probably lies here.

Antibiotics and the management of preterm premature rupture of the fetal membranes

Preterm premature rupture of membranes remains an important cause of preterm birth and neonatal morbidity and mortality. Although the underlying pathophysiology remains largely undefined, subclinical infection has been implicated both in the mechanism of membrane rupture and the resultant neonatal morbidity. The use of maternal systemic antibiotics reduces both neonatal and maternal morbidity in the expectant management of PPROM. Although concern persists over the development of resistant strains of organisms involved with neonatal sepsis, current data support the use of antibiotics in this setting. Further study is needed regarding the risks and benefits of additional tocolytic therapy or antenatal corticosteroids in the management of PPROM, and the predictors of successful and unsuccessful conservative management, and subclinical intrauterine infection. This will be helpful in the ultimate delineation of the optimal management scheme for PPROM.

Fetal growth restriction is not associated with a reduced risk for bilateral spastic cerebral palsy in very-low-birthweight infants

OBJECTIVE

To evaluate the influence of confounding and sampling bias on the relationship between fetal growth restriction in a very-low-birthweight-defined cohort (VLBW, < or =1500 g) and bilateral spastic cerebral palsy (BSCP) at early school-age.

METHODS

Three hundred twenty-four of 407 long-term survivors of a regional cohort of VLBW newborns were followed until age 6 years. We categorized as small for gestational age (SGA) all infants whose birthweight Z-score was below -2 relative to published reference values. Uni- and multivariable logistic regression models were fit to estimate the risk of BSCP associated with SGA in the total sample, in subsamples defined by gestational age, and in a gestational age-matched case-control sample.

RESULTS

In the total sample, no child below 28 weeks was SGA, and no child above 32 weeks had an appropriate birthweight for gestational age (AGA). The prevalence of BSCP was 14% in AGA and 2% in SGA infants. In both uni- and multivariable logistic regression analyses of the total sample, SGA was associated with a prominently reduced risk of BSCP (odds ratios range from 0.1 to 0.2, all 95% confidence limits exclude 1.0). However, analyses performed in samples defined by different gestational age cutoffs (24--31 weeks, 28--31 weeks) and in a sample using three gestational age-matched controls per BSCP-case did not show a protection by growth restriction (odds ratios range from 0.8 to 2.2, all 95% confidence limits include 1.0).

CONCLUSIONS

In VLBW-defined samples, the apparent protective effect of SGA for BSCP can be explained, at least in part, by the highly skewed distribution of SGA over the available gestational age range. From this follows that study cohorts should be defined by gestational age and not by birthweight. In distorted samples like this one, even controlling for gestational age does not reduce the illusion of a reduced cerebral palsy risk for growth restricted infants. Only restriction of the sample by gestational age and/or matching for gestational age reveals the absence of this apparent protective effect.

A preterm birth prevention project in Nova Scotia, Canada

OBJECTIVE

The Halifax County Preterm Birth Prevention Project was designed to evaluate the effectiveness of a population-based preterm birth (PTB) prevention program in Nova Scotia from January 1995 through June 1997 (n = 10,326).

METHODS

Preterm birth rates, adjusted for risk status and maternal age, were evaluated over time in Halifax County and compared to non-Halifax County parturients in Nova Scotia. Physician participation was evaluated by means of a mailed survey.

RESULTS

There was no appreciable change in the overall (<37 weeks) or early (<34 weeks) PTB rates within or outside Halifax County during the intervention period compared to the preintervention period. Although not significant, the very (<30 weeks) PTB rate in Halifax County decreased by 40% from 0.53 to 0.32%, while outside Halifax County it remained stable (0.43-0.42%). There was a statistically significant decrease in early and very PTB associated with spontaneous labour, as well as an apparent shift in the timing of delivery from very preterm to preterm (> or =30 weeks). Participation among responding physicians was greater for high-risk than low-risk women, but full compliance with project recommendations was low.

CONCLUSION

The overall ineffectiveness of the Halifax County Preterm Birth Prevention Project may reflect the reluctance of practitioners to fully incorporate the recommended prevention strategies into their practice. However, such interventions may reduce the risk of spontaneous early preterm birth.

Identification of biological/biochemical marker(s) for preterm delivery

Fetal and neonatal mortality and morbidity rates are strongly associated with gestational age for delivery: the risk for poor outcome increases as gestational age decreases. Attempts to predict preterm delivery (PTD, spontaneous delivery before 37 weeks' gestation) have been largely unsuccessful, and rates of PTD have not improved in recent decades. More recently, the reported associations between infections in pregnancy and PTD suggest preventive initiatives that could be taken. The overall objective of the current study is to assess whether specific markers of infection (primarily interleukin (IL) 1beta, tumour necrosis factor (TNF) alpha, IL-6, and IL-10) obtained from maternal blood during pregnancy, alone or in combination with other risk factors for PTD, permit identification of women at risk for spontaneous PTD. To achieve this objective, data are obtained from two Danish prospective cohort studies involving serial collection of maternal blood samples, newborn cord blood samples, and relevant confounders and other risk factors for PTD. The first study consists of a completed Danish regional cohort of 3000 pregnant women enrolled in a study of microbiological causes of PTD, upon which a nested case-control study of PTD in 84 cases and 400 controls has been performed. The second study is a nested case-control study of 675 PTD cases (equally divided into three gestational age categories of 24-29 weeks' gestation, 30-33 weeks' gestation, and 34-36 weeks' gestation) and 675 controls drawn from the ongoing Danish National Birth Cohort study of 100 000 pregnant women enrolled during 1997-2001. The second study will provide the opportunity to refine and retest hypotheses from the first study, as well as to explore new hypotheses. Our preliminary work suggests that a single predictive marker effectively accounting for a large proportion of PTD is unlikely to be found. Rather, a search for multiple markers indicative of the multifactorial aetiology of PTD is likely to be more successful. Knowledge gained from the proposed studies will be implemented in a third, clinical intervention study against PTD. The first phase of the clinical intervention study will be to establish a risk-assessment model based on the "best" combination of biological/biochemical measures and other factors associated with PTD in order to identify pregnant women at very high risk of PTD. The second phase will be to apply an intervention model of tailored obstetric care to the very high-risk pregnant women for PTD identified in phase one. The intervention will be carried out against each specific risk factor associated with PTD identified for the individual. The aim is to reduce the risk for PTD attributed to the combination of risk factors included in the clinical intervention study.

Stress, infection and preterm birth: a biobehavioural perspective

Preterm birth is currently the most important problem in maternal-child health in the United States. Epidemiological studies have suggested that two factors, maternal stress and maternal urogenital tract infection, are significantly and independently associated with an increased risk of spontaneous preterm birth. These factors are also more prevalent in the population of sociodemographically disadvantaged women who are at increased risk for preterm birth. Studies of the physiology of parturition suggest that neuroendocrine and immune processes play important roles in the physiology and pathophysiology of normal and preterm parturition. However, not all women with high levels of stress and/or infection deliver preterm, and little is understood about factors that modulate susceptibility to pathophysiological events of the endocrine and immune systems in pregnancy. We present here a comprehensive, biobehavioural model of maternal stress and spontaneous preterm delivery. According to this model, chronic maternal stress is a significant and independent risk factor for preterm birth. The effects of maternal stress on preterm birth may be mediated through biological and/or behavioural mechanisms. We propose that maternal stress may act via one or both of two physiological pathways: (a) a neuroendocrine pathway, wherein maternal stress may ultimately result in premature and/or greater degree of activation of the maternal-placental-fetal endocrine systems that promote parturition; and (b) an immune/inflammatory pathway, wherein maternal stress may modulate characteristics of systemic and local (placental-decidual) immunity to increase susceptibility to intrauterine and fetal infectious-inflammatory processes and thereby promote parturition through pro-inflammatory mechanisms. We suggest that placental corticotropin-releasing hormone may play a key role in orchestrating the effects of endocrine and inflammatory/immune processes on preterm birth. Moreover, because neuroendocrine and immune processes extensively cross-regulate one another, we further posit that exposure to both high levels of chronic stress and infectious pathogens in pregnancy may produce an interaction and multiplicative effect in terms of their combined risk for preterm birth. Finally, we hypothesise that the effects of maternal stress are modulated by the nature, duration and timing of occurrence of stress during gestation. A discussion of the components of this model, including a theoretical rationale and review of the available empirical evidence, is presented. A major strength of this biobehavioural perspective is the ability to explore new questions and to do so in a manner that is more comprehensive than has been previously attempted. We expect findings from this line of proposed research to improve our present state of knowledge about obstetric risk assessment for preterm birth by determining the characteristics of pregnant women who are especially susceptible to stress and/or infection, and to broaden our understanding of biological (endocrine, immune, and endocrine-immune interactions) mechanisms that may translate social adversity during pregnancy into pathophysiology, thereby suggesting intervention strategies.

Distinct molecular events suggest different pathways for preterm labor and premature rupture of membranes

OBJECTIVE

On a clinical level, the etiologies associated with premature rupture of the membranes and preterm labor are virtually identical, though these conditions end in distinctly different events. This study was designed to determine differences between preterm labor and preterm premature rupture of membranes by using molecular markers of extracellular matrix degradation and apoptosis.

STUDY DESIGN

Amniochorion and amniotic fluid samples were collected from gestational age-matched groups of women undergoing cesarean delivery before term. Samples were collected from 2 groups of women, women with premature rupture of membranes and women with preterm labor with no rupture of membranes. Changes in the expression pattern of messenger ribonucleic acid for matrix metalloproteinases (MMP), tissue inhibitor of metalloproteinases (TIMP), and pro-apoptotic (p53 and Bax) and anti-apoptotic (Bcl-2) proteins were identified by quantitative polymerase chain reaction. Enzyme-linked immunosorbent assay was used to determine the levels of these proteins in the amniotic fluid. Multiplex polymerase chain reaction was performed to study the expression of Fas-Fas ligand-associated pro-apoptotic genes. Unpaired nonparametric, 2-tailed Mann-Whitney U test was used to determine statistical significance of quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (P <.05 was considered significant).

RESULTS

Quantitative polymerase chain reaction results demonstrated an increased mRNA expression for MMP2, MMP9, and MT1-MMP and a decreased expression for TIMP2 in prematurely ruptured membranes compared with preterm labor membranes. Enzyme-linked immunosorbent assay documented increases in the amniotic fluid concentrations of immunoreactive and bioactive MMP2 and MMP9 and immunoreactive MMP3 and a decreased TIMP2 concentration in fluids obtained from the premature rupture of membranes group compared with the preterm labor group. The pro-apoptotic genes p53 and bax were up-regulated in premature rupture of membranes when compared with preterm labor. Anti-apoptotic gene (Bcl-2 ) expression was increased in preterm labor membranes compared with prematurely ruptured membranes. Interleukin-18 (a pro-apoptotic cytokine) was increased in the amniotic fluid during premature rupture of membranes compared with preterm labor. Prematurely ruptured membranes also demonstrated fragmented deoxyribonucleic acid and expression of Fas and caspase 8 (apoptosis initiator), which were all absent in preterm labor membranes.

CONCLUSIONS

We have begun to delineate 2 divergent molecular pathways for premature rupture of membranes and preterm labor. Most likely, this is the beginning of the identification of differences that will become evident with the use of molecular biology.

Risk factors for neurologic impairment among very low-birth-weight infants

Although cerebral palsy is the most common neurologic impairment among very low-birth-weight survivors, its etiology remains uncertain. Current research supports the role of both antenatal and neonatal factors in the pathogenesis of cerebral palsy among these extremely premature infants. Important antenatal risk factors include chorioamnionitis and multiple placental lesions. Maternal preeclampsia may provide neuroprotection. The major neonatal risk factors include severe cranial ultrasound abnormalities, chronic lung disease, hyperbilirubinemia, and possibly hypothyroxinemia.

Cerebral white matter damage in the preterm infant: pathophysiology and risk factors

Based on clinical, epidemiologic, and experimental studies, the aetiology of white matter damage, specifically periventricular leukomalacia (PVL), is multifactorial and involves pre- and perinatal factors possibly including genetic factors, hypoxic-ischaemic insults, infection, excess cytokines, free radical production, increased excitatory amino acid release, and trophic factor deficiencies. The article summarizes research findings about the aetiology of white matter damage and cerebral palsy in preterm infants. The information is organized according to specific antecedents, for which we present epidemiological and neurobiological data. The most important prenatal factor appears to be intrauterine infection. We discuss the evidence supporting the hypothesis that the foetal inflammatory response contributes to neonatal brain injury and later developmental disability. We recently established an animal model of excitotoxic lesions in the developing mouse brain. Brain damage was induced by intra-cortical injections of ibotenate, a glutamatergic agonist. When administered on post-natal day 5 ibotenate induced the formation of white matter cysts. Our animal model could be used to further explore the mechanisms involved in the formation of PVL. Potentially preventive strategies will be discussed.

Glucocorticoid regulation of human and ovine parturition: the relationship between fetal hypothalamic-pituitary-adrenal axis activation and intrauterine prostaglandin production

Birth in many animal species and in humans is associated with activation of hypothalamic-pituitary-adrenal function in the fetus and the increased influence of glucocorticoids on trophoblast cells of the placenta and fetal membranes. We suggest that in ovine pregnancy glucocorticoids directly increase fetal placental prostaglandin production, and indirectly increase prostaglandin production by maternal uterine tissues through the stimulation of placental estradiol synthesis. The events of ovine parturition are compared with those of human parturition. In the latter, we suggest similar direct effects of glucocorticoids on prostaglandin synthesis and metabolism in fetal membranes and similar indirect effects mediated by glucocorticoid-stimulated increases in intrauterine corticotropin-releasing hormone expression.

Mediators of fetal inflammation in extremely low gestational age newborns

To establish levels of mediators of inflammation in cord blood and postnatal serum from extremely low gestational age newborns (ELGANs, < or =28 weeks), we measured sixteen markers of inflammation by recycling immunoaffinity chromatography in 15 ELGANs who had serum sampled at days 2-5. Median levels of IL-1, IL-6, IL-8, IL-11, IL-13, TNF-alpha, G-CSF, M-CSF, GM-CSF, MIP-1alpha, and RANTES were considerably higher than published values of these inflammatory mediators from term newborns. In three of eight ELGANS who had serial measurements taken, levels of IL-1, IL-6, IL-8, IL-11, TNF-alpha, G-CSF, and MIP-1alpha declined from initially very high levels to reach an apparent baseline towards the end of the first postnatal week. In these same three infants, GM-CSF and TGF-beta1 levels increased continuously during the first week. In the other five ELGANs, no consistent changes were observed. We speculate, that in some ELGANs, a fetal systemic inflammatory response is characterized by an antenatal wave of pro-inflammatory cytokines, followed by a second, postnatal wave of anti-inflammatory cytokines. Large epidemiologic studies are needed to clarify relationships among inflammation markers and their expression in the fetal and neonatal circulation over time. Such studies would also add to our understanding of the possible role of inflammatory mediators in the pathophysiology of the major complications of extreme prematurity.

Effect of lipopolysaccharide on uterine contractions and prostaglandin production in pregnant rats

OBJECTIVE

Our aim was to evaluate the effect of lipopolysaccharide on prostaglandin production and on contraction of isolated myometrial strips from preterm pregnant rats.

STUDY DESIGN

Pregnant Wistar rats on day 17 of gestation were killed 3 hours after intraperitoneal injection of lipopolysaccharide (1.5 mg/kg) or vehicle, with or without pretreatment with indomethacin (5 mg/kg administered intraperitoneally) 1 hour beforehand. Concentrations of endotoxin in maternal serum and amniotic fluid, prostaglandin F2alpha and prostaglandin E2 in amniotic fluid, and progesterone in maternal serum were determined. Longitudinal uterine strips were prepared, placed in organ chambers with Krebs-Ringer solution, aerated with 95% oxygen and 5% carbon dioxide (37 degrees C, pH approximately 7.4), and equilibrated at 1g passive tension. Concentration-contraction relationships to oxytocin were determined. Samples of bathing solution were collected 10 minutes after the concentration of oxytocin was maximal. Prostaglandins and progesterone were measured by radioimmunoassay and endotoxin was measured by the Endospecy (Seikagaku Kogyo, Tokyo, Japan) kit.

RESULTS

Lipopolysaccharide treatment significantly increased the levels of prostaglandin F2alpha and prostaglandin E2 in amniotic fluid. Treatment with lipopolysaccharide inhibited the production and release of prostaglandin F2alpha and prostaglandin E2 that were activated by oxytocin in uterine strips and increased the sensitivity of strips to the contractile effect of oxytocin. Indomethacin did not affect the basal or the lipopolysaccharide-activated levels of endotoxin in serum and amniotic fluid and exerted a counteraction on lipopolysaccharide-induced increases in concentrations of prostaglandin F2alpha and prostaglandin E2 in amniotic fluid. Indomethacin counteracted oxytocin-activated production and release of prostaglandin F2alpha and prostaglandin E2 in uterine tissues after lipopolysaccharide administration without changing the sensitivity of uterine strips to oxytocin. Concentrations of progesterone were not changed after lipopolysaccharide, indomethacin, or their combined application, which suggests that the changes described were not associated with alterations in the levels of the hormone.

CONCLUSIONS

The activation of the uterine contractile system by prostaglandin and oxytocin during intra-amniotic infection may be one of the causes of preterm delivery. A combination of an oxytocin receptor antagonist and an inhibitor of cyclooxygenase may be beneficial in prevention or treatment of preterm labor.

Performance characteristics of putative tests for subclinical chorioamnionitis

OBJECTIVE

To evaluate amniotic fluid glucose, matrix metalloproteinase (MMP)-9, interleukin (IL)-6, and IL-12 for diagnosing subclinical chorioamnionitis in women with preterm labor.

METHODS

Forty-four women in preterm labor at 22-35 weeks gestation with suspected subclinical chorioamnionitis underwent amniocentesis. Amniotic fluid analysis included Gram stain, culture, and determination of glucose, MMP-9, IL-6, and IL-12 concentrations. Median values of these analytes were compared using the Mann-Whitney U test. Sensitivity, specificity, and positive and negative predictive values were calculated for tests using a positive amniotic fluid culture or delivery within 24 hours as the key outcome variables.

RESULTS

Amniotic fluid concentrations of glucose, MMP-9, and IL-6 correlated closely with positive culture or delivery within 24 hours. IL- 12 concentrations did not correlate with either a positive culture or delivery within 24 hours.

CONCLUSIONS

Amniotic fluid glucose, MMP-9, and IL-6 reliably predict microbial invasion of the amniotic cavity or imminent delivery. IL- 12 values did not correlate with amniotic fluid culture results or imminent delivery.

Place of amniocentesis in the assessment of preterm labour

OBJECTIVE

To evaluate the benefits and indications for amniocentesis in cases of preterm labor with or without preterm rupture of membranes.

METHOD

A review of the literature on amniocentesis in cases of intra-amniotic infection.

RESULTS

Amniocentesis is an invasive method that allows the diagnosis of intra-amniotic infection. However, no randomized trials have been performed from which we can assess the benefits and complications of amniocentesis in preterm labor.

CONCLUSION

The published data do not justify the routine practice of amniocentesis in preterm labor. More data are needed to evaluate the benefits and complications of this practice. Only randomized trials of patients in preterm labor, comparing those who undergo amniocentesis with those who do not, will clarify the indications for this procedure.

Maternal serum interleukin 6 levels in preterm labor: prediction of admission-to-delivery interval

OBJECTIVE

To evaluate the diagnostic value of maternal serum interleukin 6 (IL-6), C-reactive protein (CRP) levels and white blood cell (WBC) count for the prediction of preterm labor and length of admission-to-delivery interval in patients with preterm labor.

METHODS

Maternal serum IL-6, CRP and WBC count were prospectively determined in eighty-two patients in preterm labor and 21 controls. Data was analyzed in study and control groups, and for the assessment of clinical and laboratory risk factors in the prediction of admission-to-delivery interval in the study group.

RESULTS

Maternal serum IL-6 levels were significantly higher in the study group than controls. The IL-6 value associated with the highest percent of true positives and true negatives for the prediction of preterm labor was 5 pg/ml. The area under curve of maternal IL-6 was significantly higher than the area under curve of of CRP and WBC count. In the study group maternal serum IL-6 levels were significantly higher in patients delivered within 2 and 7 days than the nondelivering ones and a cut off value of 8.3 pg/ml was determined for estimation of preterm delivery.

CONCLUSION

Maternal serum IL-6 is a reliable marker in the prediction and management of preterm labor and delivery.

Clinical significance and outcome of preterm prelabor rupture of membranes: population-based study

OBJECTIVE

To evaluate maternal characteristics and neonatal and maternal birth outcome in cases of prelabor rupture of membranes (PPROM) in a non-selected parturient population.

STUDY DESIGN

The study population consisted of 5660 singleton preterm births (24-36 weeks gestation) occurring between 1988 and 1997 at the Soroka University Medical Center in Israel. Parturients with no prenatal care were excluded from the study. A cross-sectional study was designed between two groups. The study group consisted of patients with PPROM (n=968) and the comparison group consisted of patients without PPROM (n=4692). The data were analyzed by SPSS package. Information was obtained using a computerized database based on detailed obstetrical records. Logistic regression was used to assess the contribution of different risk factors to PPROM.

RESULTS

PPROM was associated with a significantly lower gestational age (24-32 weeks) and birth weight (<2500 g) than those with intact membranes. The rates of chorioamnionitis and urinary infection were found significantly higher in the PPROM group compared with women without PPROM (16.5 vs. 2.7%; 5.1 vs. 3.3%, respectively) (P<0.001). The rate of endometritis and bacteremia in the postpartum period were significantly higher in women with PPROM compared with controls 2.8 vs. 1.4%, (P=0.003) and 9.4 vs. 5%, (P=0.001), respectively. Total perinatal mortality rates were significantly higher in the group without PPROM 10.5 vs. 7.2% (P=0.01), however, rates of postpartum death were higher in the PPROM group 5.5 vs. 4% (P<0.01). When adjusted for recognized risk factors using logistic regression analysis, infection of amniotic fluid (OR=6.6) and genito-urinary tract infection (OR=1.64) remained the independent risk factors associated with PPROM.

CONCLUSIONS

Infectious morbidity in patients with preterm prelabor rupture of membranes and preterm delivery remained an important risk factor for obstetrical and neonatal complications.

The relationships between antenatal management, the cause of delivery and neonatal outcome in a large cohort of very preterm singleton infants

OBJECTIVE

To determine whether the cause of very preterm delivery influences neonatal outcome.

DESIGN

A cohort study of 685 consecutive singletons born before 33 weeks of gestation.

METHODS

Causes of birth and perinatal outcome variables were correlated for statistical significance by uni- and multi-variate analyses.

RESULTS

Intrauterine growth retardation or pre-eclampsia were associated with a higher rate of respiratory distress syndrome compared with prolonged rupture of membranes, after controlling for gestational age, antenatal corticosteroid therapy, antenatal antibiotic administration, mode of delivery and origin (inborn or outborn) (adjusted OR 3.12; 95% CI 1.55-6.28). The prevalence of grade 3-4 intraventricular haemorrhage or cystic periventricular leukomalacia was 25% in newborn babies born after intrauterine infection or prolonged rupture of membranes. Among infants born after intrauterine growth retardation/pre-eclampsia, the rate of severe intraventricular haemorrhage was 3.2% and the rate of periventricular leukomalacia was 0.9%. Compared with intrauterine infection and after controlling for potential confounding covariates, intrauterine growth retardation/pre-eclampsia was associated with a lower rate of periventricular leukomalacia (adjusted OR 0.08; 95% CI 0.02-0.41). In the same multiple logistic regression model, antenatal corticosteroid administration was associated with a lower incidence of periventricular leukomalacia (adjusted OR 0.36; 95% CI 0.16-0.79).

CONCLUSIONS

The cause of very preterm delivery has an important influence on neonatal outcome.

Antecedents of cerebral palsy in very low-birth weight infants

Research from the last two decades provides directions for efforts to prevent CP in VLBW infants. The pathogenesis of CP seems to involve factors operating both during pregnancy and in the neonatal period. The most important prenatal factor appears to be intrauterine infection. Perinatal infection and other risk factors, such as the death of a co-twin, placental abruption, and cerebral ischemia, could trigger a cytokine cascade resulting in damage to the developing brain. The low frequency of intrauterine infection in mothers with preeclampsia might explain the apparent protective effect of this disorder. If the brain damage attributed to intrauterine infection and other risk factors involves cytokines as intermediates, then blockade of the proinflammatory cascade or promotion of endogenous inhibitors might prevent CP. Other potentially preventive strategies include corticosteroids given to mothers (but not those given to neonates) and thyroid hormone.

Role of the fetus in perinatal infection and neonatal brain damage

Increasing evidence supports the view that infants exposed to perinatal infection are at increased risk for brain injury. We suggest that elevated cytokines in the amniotic fluid or in the fetal circulation be viewed as a humoral expression and that inflammatory cells in chorionic plate or umbilical cord blood vessel walls be viewed as a morphologic expression of the fetal inflammatory response. We discuss the evidence supporting the hypothesis that the fetal inflammatory response contributes to neonatal brain injury and later developmental disability. Little support has been found for a maternal contribution. Intervention should be designed with the fetus in mind.

Antenatal brain injury: aetiology and possibilities of prevention

Although the aetiology of antenatal brain injury is often unclear, procedures can be employed to prevent or reduce the risk of injury. Defective neuropore closure can be prevented by periconceptional administration of folic acid, and the incidence of other severe malformations and genetic disorders can be reduced by early identification and termination of pregnancy. Antenatal identification of IUGR, administration of corticosteroids to cases with pending preterm birth, and treatment of maternal/fetal infections would also reduce the incidence of injury. Mothers can decrease the risk of injury by maintaining a good diet, avoiding smoking, alcohol intake and exposure to TORCH infections during pregnancy.

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Up to 30% of mothers develop acute pyelonephritis if asymptomatic bacteriuria is untreated. Asymptomatic bacteriuria may have a role in preterm birth, or it may be a marker for low socioeconomic status and thus, low birth weight.

OBJECTIVES

The objective of this review was to assess the effect of antibiotic treatment for asymptomatic bacteriuria on persistent bacteriuria during pregnancy, the risk of preterm delivery and the development of pyelonephritis after delivery.

SEARCH STRATEGY

I searched the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Randomised trials comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed.

MAIN RESULTS

Thirteen studies were included. Overall the study quality was not strong. Antibiotic treatment compared to placebo or no treatment was effective in clearing asymptomatic bacteriuria (odds ratio 0.07, 95% confidence interval 0.05 to 0.10). The incidence of pyelonephritis was reduced (odds ratio 0.25, 95% confidence interval 0.19 to 0.32). Antibiotic treatment was also associated with a reduction in the incidence of preterm delivery or low birth weight babies (odds ratio 0.60, 95% confidence interval 0.45 to 0.80).

REVIEWER'S CONCLUSIONS

Antibiotic treatment appears to be effective in reducing the risk of pyelonephritis in pregnancy. An apparent reduction in preterm delivery is consistent with current theories about the role of infection in preterm birth, but this association should be interpreted with caution.

LPS mediated production of IL-1, PGE2 and PGF2alpha from term decidua involves tumour necrosis factor and tumour necrosis factor receptor p55

Prostaglandins, with cytokines involved as intermediate factors, may have an essential role in premature labour when infection is present. We therefore wanted to study tumour necrosis factor (TNF), in cytokine and prostaglandin production in reproductive tissue. Decidual cell cultures were established and cells were stimulated with lipopolysaccharides (LPS). Media concentrations of TNF, interleukin-1 (IL-1), IL-6 and prostaglandin E2 and F2alpha were analysed, and involvement of LPS receptor CD14, TNF and TNF receptors (p55 and p75) were analysed, by studying effects after administration of specific antibodies. LPS induced an early peak elevation of TNF, with a subsequent release of IL-1, IL-6 and prostaglandins. Antibodies against CD14 inhibited these LPS effects. TNF antibodies reduced production of IL-1 and prostaglandins, whereas no significant influence on IL-6 production was observed. Antibodies against the TNF receptor p55 reduced all observed TNF effects. In contrast, p75 antibodies did not influence cytokine or prostaglandin production in this system. Our results suggest that increased TNF production is a prerequisite for LPS stimulated production of IL-1 and prostaglandins from decidual cells. LPS may directly stimulate IL-6 production. Of the two TNF receptors studied, only p55 seemed to be involved in the TNF signal transduction.

Characterization of the amnion-derived AV3 cell line for use as a model for investigation of prostaglandin-cytokine interactions in human amnion

Increased production of prostaglandins and cytokines by amnion, particularly prostaglandin (PG) E2, interleukin (IL)-6 and IL-8, is thought to be an important event in infection-associated preterm labour. We characterized the amnion-derived AV3 cell line to determine its appropriateness as a model for investigation of the regulation of amnion cytokine and PG production. Amnion-derived AV3 cells were treated with tumour necrosis factor-alpha (TNF-alpha, interleukin-1beta (IL-1beta), epidermal growth factor (EGF) and phorbol 12-myristate 13-acetate (PMA) and IL-6, IL-8 and prostaglandin production was determined by immunoassay. Production of IL-6 and IL-8 rose dramatically with all treatments. PGE2, but not PGF2alpha or 6-keto-PGF1alpha, biosynthesis was also increased in a concentration-dependent manner with all treatments. A rapid increase in PGHS-2 (but not PGHS-1) mRNA expression was observed in response to TNF-alpha and IL-1beta. We conclude that the AV3 cell line inflammatory response profile is similar to those observed in primary amnion and other amnion-derived cell lines, and is an appropriate model for human amnion.

15-Deoxy-Delta(12,14)-prostaglandin J(2), a ligand for peroxisome proliferator-activated receptor-gamma, induces apoptosis in JEG3 choriocarcinoma cells

Apoptosis has been described in placental (trophoblast) tissues during both normal and abnormal pregnancies. We have studied the effects of the cyclopentenone prostaglandins (PGs) on trophoblast cell death using JEG3 choriocarcinoma cells. PGJ(2), Delta(12)PGJ(2), and 15-deoxy-Delta(12,14)-PGJ(2) (15dPGJ(2)) (10 microM) significantly reduced mitochondrial activity (MTT assay) over 16 h by 17.4 +/- 4.7%, 28 +/- 9.3%, and 62.5 +/- 2.8%, respectively (mean +/- sem), while PGA(2) and PGD(2) had no effect. The synthetic PPAR-gamma ligand ciglitizone (12.5 microM) had a potency similar to 15dPGJ(2) (69 +/- 3% reduction). Morphological examination of cultures treated with PGJ(2) and its derivatives revealed the presence of numerous cells with dense, pyknotic nuclei, a hallmark of apoptosis. FACS analysis revealed an abundance (approximately 40%) of apoptotic cells after 16-h treatment with 15dPGJ(2) (10 microM). The caspase inhibitor ZVAD-fmk (5 microM) significantly diminished the apoptotic effects of Delta(12)PGJ(2) and 15dPGJ(2). JEG3 cells expressed PPAR-gamma mRNA by Northern analysis. These novel findings imply a role for PPAR-gamma ligands in various processes associated with pregnancy and parturition.

Key enzymes of prostaglandin biosynthesis and metabolism. Coordinate regulation of expression by cytokines in gestational tissues: a review

Preterm labor is frequently associated with ascending intrauterine infection, accompanied by leukocytes infiltration and enhanced local production of cytokines and other inflammatory mediators. The resulting amplification of the inflammatory response, and of prostanoid production in particular, is postulated to be a principal mechanism of infection-driven preterm labor. In this review the effects of pro- and anti-inflammatory cytokines are discussed with respect to the expression of enzymes involved in three key steps of prostanoid biosynthesis and metabolism: liberation of arachidonic acid (AA), conversion of AA to bioactive prostanoids, and prostanoid catabolism. We suggest that by exerting coordinate actions on all three key steps, through multiple molecular mechanisms, inflammatory cytokines acutely up-regulate prostanoid production in intrauterine tissues.

Presence of four tissue inhibitors of matrix metalloproteinases (TIMP-1, -2, -3 and -4) in human fetal membranes

PROBLEM

Matrix metalloproteinases play a critical role in fetal membrane extracellular matrix (ECM) homeostasis. Remodeling of the ECM during normal placental development is a balanced activity between various matrix metalloproteinases and their tissue-specific counter-regulatory proteins (tissue inhibitors of matrix metalloproteinases [TIMPs]). We have reported the presence of TIMP-1 and TIMP-2 in placental membranes in culture. In this study we have investigated the membrane expression of TIMP-1 and TIMP-2 during labor and nonlabor conditions and also the presence of two novel TIMP family members (TIMP-3 and TIMP-4).

METHOD OF STUDY

Amniochorionic membranes collected from women undergoing Cesarean section and were cultured in an organ explant system. Membranes were also collected from laboring women after vaginal delivery. Samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) using primers specific for TIMP-1, TIMP-2, TIMP-3, and TIMP-4. Localization of TIMP mRNAs was accomplished by in situ hybridization, and peptides were localized by immunocytochemistry.

RESULTS

RT-PCR data demonstrated the expression of all the TIMPs in tissues from laboring and nonlaboring women as well as in cultured membranes. TIMP-4 expression was seen in RT-PCR, however, only a faint band was visible in all the tissues tested. In situ hybridization localized the TIMP mRNAs to the amnion, chorion, and to scattered cells in the connective tissue.

CONCLUSION

Human fetal membrane cells (amniochorion and decidua) express mRNA for all the TIMPs studied so far.

Labor-associated changes in interleukin-10 production and its regulation by immunomodulators in human choriodecidua

Parturition is associated with increased production of proinflammatory mediators by gestational tissues. Interleukin-10 (IL-10) is an antiinflammatory cytokine produced by human chorion, decidual, and trophoblast tissues. To study the effects of immunomodulators on IL-10, IL-6, and PGE2 production by human choriodecidua before and after labor, an organ explant system was established. Tissue disks (6 mm) were excised from choriodecidual membranes obtained at term by cesarean section before labor (n=6-7) or after spontaneous vaginal delivery (n=7-8). After 24-h equilibration in medium, the tissues were treated with IL-1beta (10 ng/mL), tumor necrosis factor-alpha (100 ng/mL), lipopolysaccharide (5 microg/mL), dexamethasone (1 micromol/ L), or an appropriate vehicle control (n=3 wells/treatment) for 24 h. Media were harvested, and IL-10, IL-6, and PGE2 concentrations were determined by immunoassay. Basal choriodecidual production rates of IL-10 were significantly decreased with labor (P < 0.001), whereas PGE2 and IL-6 production rates increased. The production of all three substances was increased by IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, but inhibited by dexamethasone. In contrast to PGE2 and IL-6, there was significantly increased responsiveness of IL-10 production to inflammatory stimuli after labor, but decreased responsiveness to the inhibitory effects of dexamethasone. These data indicate that IL-10 could play a role in modulating or promoting resolution of the inflammatory processes associated with labor at term and with intrauterine infection-associated preterm labor.

Infection remote from the brain, neonatal white matter damage, and cerebral palsy in the preterm infant

This review synthesizes the literature supporting the hypothesis that infection during or even before pregnancy remote from the fetal brain leads to neonatal white matter damage (NWMD) and its long-term sequelae, including cerebral palsy. First, a framework of five dimensions is presented, including the spectrum of NWMD, its relationship with gestational age, its clinical spectrum, the expressions and correlates of infection, and the mother/child dyad. Second, a summary of the plethora of support for the remote infection/NWMD-hypothesis is presented by drawing on studies published over the past three decades. Although an epidemiological perspective is prominent, we invoke molecular explanations (especially the cytokine hypothesis) for observed associations. Third, the article concludes with a section on future studies needed to characterize and eliminate (pre-) pregnancy infections in the mother and to identify and evaluate potentially neuroprotective strategies in the fetus.

Antepartum home care for high-risk pregnant women

Home care for women experiencing complications of pregnancy is a rapidly growing specialty. A variety of models of antepartum home care have emerged. Provision of effective antepartum home care requires knowledge and clinical skills in perinatal and home health nursing and an understanding of the structure and function of the home health care system. Nursing care in the home encompasses case coordination, maternal and fetal assessment, maternal education regarding the woman's risk situation and self-monitoring requirements, and provision of support. Antepartum home care for conditions such as hypertension in pregnancy, preterm labor, and hyperemesis gravidarum is discussed.

The fetal inflammatory response syndrome

OBJECTIVE

The objective of this study was to determine the frequency and clinical significance of a systemic inflammatory response as defined by an elevated plasma interleukin-6 concentration in fetuses with preterm labor or preterm premature rupture of membranes.

STUDY DESIGN

Amniocenteses and cordocenteses were performed in 157 patients with preterm labor and preterm premature rupture of membranes. Written informed consent and multi-institutional review board approvals were obtained. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as mycoplasmas. Amniotic fluid and fetal plasma interleukin-6 concentrations were measured with a sensitive and specific immunoassay. Statistical analyses included contingency tables, receiver operating characteristic curve analysis, and multiple logistic regression.

RESULTS

One hundred five patients with preterm labor and 52 patients with preterm premature rupture of membranes were included in this study. The overall prevalence of severe neonatal morbidity (defined as the presence of respiratory distress syndrome, suspected or proved neonatal sepsis, pneumonia, bronchopulmonary dysplasia. intraventricular hemorrhage, periventricular leukomalacia, or necrotizing enterocolitis) among survivors was 34.8% (54/155). Neonates in whom severe neonatal morbidity developed had higher concentrations of fetal plasma interleukin-6 than fetuses without development of severe neonatal morbidity (median 14.0 pg/mL, range 0.5 to 900 vs median 5.2 pg/mL, range 0.3 to 900, respectively; P < .005). Multivariate analysis was performed to explore the relationship between the presence of a systemic fetal inflammatory response and subsequent neonatal outcome. To preserve a meaningful temporal relationship between the results of fetal plasma interleukin-6 concentrations and the occurrence of severe neonatal morbidity, the analysis was restricted to 73 fetuses delivered within 7 days of cordocentesis who survived. The prevalence of severe neonatal morbidity in this subset of patients was 53.4% (39/73). A fetal plasma interleukin-6 cutoff value of 11 pg/mL was used to define the presence of a systemic inflammatory response. The prevalence of a fetal plasma interleukin-6 level > 11 pg/mL was 49.3% (36/73). Fetuses with fetal plasma interleukin-6 concentrations > 11 pg/mL had a higher rate of severe neonatal morbidity than did those with fetal plasma interleukin-6 levels < or = 11 pg/mL (77.8% [28/36] vs 29.7% [11/37], respectively; P < .001). Stepwise logistic regression analysis demonstrated that the fetal plasma interleukin-6 concentration was an independent predictor of the occurrence of severe neonatal morbidity (odds ratio 4.3, 95% confidence interval 1 to 18.5) when adjusted for gestational age at delivery, the cause of preterm delivery (preterm labor or preterm premature rupture of membranes), clinical chorioamnionitis, the cordocentesis-to-delivery interval, amniotic fluid culture, and amniotic fluid interleukin-6 results.

CONCLUSION

A systemic fetal inflammatory response, as determined by an elevated fetal plasma interleukin-6 value, is an independent risk factor for the occurrence of severe neonatal morbidity.

Polymerase chain reaction in the detection of microbes in amniotic fluid

Intra-amniotic infection during pregnancy can be caused by bacteria, viruses or protozoa, Toxoplasma gondii for example. Bacterial intrauterine infections are connected with premature birth, premature rupture of fetal membranes, and infective complications of both the mother and the newborn. Viral infections and Toxoplasma gondii can cause fetal malformations and illness with serious sequelae to the infant or fetal death in utero. Determining the causative agent is important and often greatly affects the prognosis of the newborn. Amniotic fluid is in most cases easily and safely obtainable during the second and third trimester and can be used in several microbiological assays. These include bacterial and viral cultures, Gram staining, quantitative assays for immunoglobulins or cytokines, and polymerase chain reaction (PCR) for detecting microbial DNA. This review concentrates on broad-spectrum or universal bacterial PCR for detection of bacterial DNA in amniotic fluid and on PCR assays for certain clinically important viruses and for Toxoplasma gondii.

Reduced production of PGE2 and PGF2 alpha from decidual cell cultures supplemented with N-3 polyunsaturated fatty acids

A diet rich in n-3 polyunsaturated fatty acid (PUFA) may reduce the intrauterine production of prostaglandins and prolong pregnancy. We tested this hypothesis by assessing the influence of various PUFAs on the spontaneous production of PGE2 and PGF2 alpha from decidual cell cultures. In addition, we assessed prostaglandin and cytokine production stimulated by lipopolysaccharides (LPS) in order to mimic parturition where infection is involved. In both settings, we found that after supplementing with n-3 PUFA, PGE2 and PGF2 alpha were significantly reduced. After supplementing with n-6 PUFA, there was a significant increase in both prostaglandins. Both n-3 and n-6 PUFAs reduced the production of interleukin 1 (IL-1), while n-6 PUFAs reduced TNF production. PUFAs did not influence IL-6 production. Our findings support the hypothesis that dietary n-3 PUFA may prolong pregnancy by reducing intrauterine production of prostaglandins.