Preterm birth and infection: pathogenic possibilities

Factors Influencing Neonatal Gut Microbiome and Health with a Focus on Necrotizing Enterocolitis

Maturational changes in the gut start in utero and rapidly progress after birth, with some functions becoming fully developed several months or years post birth including the acquisition of a full gut microbiome, which is made up of trillions of bacteria of thousands of species. Many factors influence the normal development of the neonatal and infantile microbiome, resulting in dysbiosis, which is associated with various interventions used for neonatal morbidities and survival. Extremely low gestational age neonates (<28 weeks' gestation) frequently experience recurring arterial oxygen desaturations, or apneas, during the first few weeks of life. Apnea, or the cessation of breathing lasting 15-20 s or more, occurs due to immature respiratory control and is commonly associated with intermittent hypoxia (IH). Chronic IH induces oxygen radical diseases of the neonate, including necrotizing enterocolitis (NEC), the most common and devastating gastrointestinal disease in preterm infants. NEC is associated with an immature intestinal structure and function and involves dysbiosis of the gut microbiome, inflammation, and necrosis of the intestinal mucosal layer. This review describes the factors that influence the neonatal gut microbiome and dysbiosis, which predispose preterm infants to NEC. Current and future management and therapies, including the avoidance of dysbiosis, the use of a human milk diet, probiotics, prebiotics, synbiotics, restricted antibiotics, and fecal transplantation, for the prevention of NEC and the promotion of a healthy gut microbiome are also reviewed. Interventions directed at boosting endogenous and/or exogenous antioxidant supplementation may not only help with prevention, but may also lessen the severity or shorten the course of the disease.

Preterm Prelabor Rupture of Membranes Linked to Vaginal Bacteriome of Pregnant Females in the Early Second Trimester: a Case-Cohort Design

Preterm prelabor rupture of membranes (PPROM) is a major cause of spontaneous preterm birth (sPTB), one of the greatest challenges facing obstetrics with complicated pathogenesis. This case-cohort study investigated the association between vaginal bacteriome of singleton pregnant females in the early second trimester and PPROM. The study included 35,255 and 180 pregnant females with PPROM as cases and term-birth without prelabor rupture of membranes (TWPROM) and term prelabor rupture of membranes (TPROM) pregnant females as controls, respectively. Using 16S rRNA sequencing, the vaginal microbiome traits were analyzed. Females with PPROM had higher alpha and beta diversity (P < 0.05) than TWPROM and TPROM. The presence of L. mulieris was associated with a decreased risk of PPROM (adjusted odds ratio [aOR] = 0.35; 95% confidence interval [CI]: 0.17-0.72) compared with TWPROM. Meanwhile, the presence of Megasphaera genus (aOR = 2.27; 95% CI: 1.09-4.70), Faecalibacterium genus (aOR = 3.29; 95% CI: 1.52-7.13), Bifidobacterium genus (aOR = 3.26; 95% CI: 1.47-7.24), Xanthomonadales genus (aOR = 2.76; 95% CI: 1.27-6.01), Gammaproteobacteria class (aOR = 2.36; 95% CI: 1.09-5.14), and Alphaproteobacteria class (aOR = 2.45; 95% CI: 1.14-5.26) was associated with an increased risk of PPROM compared with TWPROM. Our results indicated that the risk of PPROM can decrease with vaginal L. mulieris but increase with high alpha or beta diversity, and several vaginal bacteria in pregnant females may be involved in the occurrence of PPROM.

Differential Effect of Vaginal Microbiota on Spontaneous Preterm Birth among Chinese Pregnant Women

Objective

The effect of vaginal microbiota on spontaneous preterm birth (sPTB) has not been fully addressed, and few studies have explored the associations between vaginal taxa and sPTB in the gestational diabetes mellitus (GDM) and non-GDM groups, respectively. Study Design. To minimize external interference, a total of 41 pregnant women with sPTB and 308 controls (pregnant women without sPTB) from same regain were enrolled in this case-cohort study. Controls were randomly selected at baseline. With the exception of GDM, other characteristics were not significantly different between the two groups. Vaginal swabs were collected at early second trimester. Using 16S amplicon sequencing, the main bioinformatics analysis was performed on the platform of QIIME 2. Vaginal microbiota traits of the sPTB group were compared with controls. Finally, the effects of binary taxa on sPTB in the GDM group and the non-GDM group were analyzed, respectively.

Results

The proportion of GDM in the sPTB (19.51%) was higher than the controls (7.47%, P = 0.018). The vaginal microbiota of pregnant women with sPTB exhibited higher alpha diversity metrics (observed features, P = 0.001; Faith's phylogenetic diversity, P = 0.013) and different beta diversity metrics (unweighted UniFrac, P = 0.006; Jaccard's distance, P = 0.004), compared with controls. The presence of Lactobacillus paragasseri/gasseri (aOR: 3.12, 95% CI: 1.24-7.84), Streptococcus (aOR: 3.58, 95% CI: 1.68-7.65), or Proteobacteria (aOR: 3.39, 95% CI: 1.55-7.39) was associated with an increased risk of sPTB in the non-GDM group (P < 0.05). However, the relative abundance of novel L. mulieris (a new species of the L. delbrueckii group) was associated with a decreased risk of sPTB (false discovery rate, 0.10) in all pregnant women.

Conclusion

GDM may modify the association of vaginal taxa with sPTB, suggesting that maternal GDM should be considered when using vaginal taxa to identify pregnant women at high risk of sPTB.

Chlamydia trachomatis Screening and Treatment in Pregnancy to Reduce Adverse Pregnancy and Neonatal Outcomes: A Review

Chlamydial trachomatis infection has been associated with adverse pregnancy and neonatal outcomes such as premature rupture of membranes, preterm birth, low birth weight, conjunctivitis, and pneumonia in infants. This review evaluates existing literature to determine potential benefits of antenatal screening and treatment of C. trachomatis in preventing adverse outcomes. A literature search revealed 1824 studies with 156 full-text articles reviewed. Fifteen studies were selected after fulfilling inclusion criteria. Eight studies focused on chlamydial screening and treatment to prevent adverse pregnancy outcomes such as premature rupture of membranes, preterm birth, low birth weight, growth restriction leading to small for gestational age infants, and neonatal death. Seven studies focused on the effects of chlamydial screening and treatment on adverse infant outcomes such as chlamydial infection including positive mucosal cultures, pneumonia, and conjunctivitis. Given the heterogeneity of those studies, this focused review was exclusively qualitative in nature. When viewed collectively, 13 of 15 studies provided some degree of support that antenatal chlamydial screening and treatment interventions may lead to decreased adverse pregnancy and infant outcomes. However, notable limitations of these individual studies also highlight the need for further, updated research in this area, particularly from low and middle-income settings.

Chlamydia trachomatis Infection in Pregnancy: The Global Challenge of Preventing Adverse Pregnancy and Infant Outcomes in Sub-Saharan Africa and Asia

Screening and treatment of sexually transmitted infections (STIs) in pregnancy represents an overlooked opportunity to improve the health outcomes of women and infants worldwide. Although Chlamydia trachomatis is the most common treatable bacterial STI, few countries have routine pregnancy screening and treatment programs. We reviewed the current literature surrounding Chlamydia trachomatis in pregnancy, particularly focusing on countries in sub-Saharan Africa and Asia. We discuss possible chlamydial adverse pregnancy and infant health outcomes (miscarriage, stillbirth, ectopic pregnancy, preterm birth, neonatal conjunctivitis, neonatal pneumonia, and other potential effects including HIV perinatal transmission) and review studies of chlamydial screening and treatment in pregnancy, while simultaneously highlighting research from resource-limited countries in sub-Saharan Africa and Asia.

Interval laparoscopic abdominal cerclage for recurrent pregnancy loss

Abdominal cerclages are necessary when the standard trans-vaginal cerclages fail or anatomical abnormalities preclude the vaginal placement. In 1965, Benson and Durfee described an abdominal approach to cerclage, a procedure that was applied to congenitally short or surgically amputated cervices. Thirty-eight women with history of either recurrent mid-trimester pregnancy losses, short cervix or failed vaginal cerclage had trans-abdominal cerclage, of which 30 were done laparoscopically. A 5-mm non-absorbable needled polyester fibre tape (Mersilene) suture was placed laparoscopically at the level of the internal os as an interval procedure. All the procedures were successful. All women were discharged on post-operative day 2 and none of them required blood transfusions. There were no intraoperative or post-operative complications. Subsequently, 15 patients conceived and the foetal survival rate recorded was as high as 85.71%. Some patients manifest severe cervical injures, and others have apparent congenital absence of the cervix, rendering Shirodkar or McDonald cerclage technically difficult or impossible. The main interest of this technique is to avoid a laparotomy; thus, reducing the morbidities of a laparotomy and also the recovery time post-surgery.

Predictors of Outcomes of Non-Elective Cervical Cerclages

BACKGROUND

Non-elective cervical cerclages are associated with significant perinatal complications. There is scant available information about what the predictors of these outcomes are, thus making counselling difficult.

OBJECTIVE

To identify which factors predict delivery at or beyond 28, 34, and 37 weeks' gestation in women with emergency/rescue cervical cerclage.

METHODS

We conducted a retrospective cohort study of nonelective cerclages over 10 years in our centre. We included women with singleton pregnancies, morphologically normal fetuses, and a cervix dilated to at least 1 cm. Our primary outcome was delivery at or beyond 28 weeks' gestation, and secondary outcomes consisted of delivery at or beyond 34 and 37 weeks' gestation. Descriptive statistical and logistic regression analyses were performed.

RESULTS

We identified a total of 69 cases, and 47 met the inclusion criteria; 44.6% of these women delivered at or beyond 28 weeks' gestation. Membranes seen in the vagina on ultrasound and postcerclage preterm premature rupture of membranes decreased the chance of delivery at or beyond 28 weeks by 81.7% (OR 0.183; 95% CI 0.048 to 0.703) and 95% (OR 0.050; 95% CI 0.006 to 0.429), respectively. The same factors were predictive of deliveries at or beyond 34 and 37 weeks' gestation.

CONCLUSION

Membranes seen in the vagina on ultrasound and postcerclage pre-labour premature rupture of membranes were the strongest predictors of failure to reach 28 weeks' gestation. This information is of critical importance when counselling patients about non-elective cervical cerclage.

The Feasibility of a Modified Method of Laparoscopic Transabdominal Cervicoisthmic Cerclage During Pregnancy

OBJECTIVE

To evaluate a modified laparoscopic transabdominal cervicoisthmic cerclage (LTCC) technique after failure of transvaginal cerclage during pregnancy in women with cervical weakness.

MATERIALS AND METHODS

Eighty women in whom transvaginal cerclage was unsuccessful or who were anatomically unsuitable for the procedure underwent modified LTCC between January 2003 and December 2008 at Keimyung University, Dongsan Medical Center, Daegu, South Korea. The modified LTCC was performed using a polyfilament polyester double-armed needle that was sutured laterally to the uterine vessels at the level of the internal cervical os. Survival of the fetus was used to calculate the successful pregnancy rate of this modified LTCC. The relationship between successful pregnancy rate and clinical variables was evaluated using a chi-squared test and a Mann-Whitney U test.

RESULTS

The mean gestational age was 12.1 weeks (range, 11-15 weeks). The operation time was 52 minutes (range, 25-100 minutes). The successful pregnancy rate was 90% (72/80 pregnancies), with a mean gestational age of 36.3±2.7 weeks. The mean newborn weight was 2690 g (range, 1860-3750 g). Eight pregnancies were lost in the first and second trimesters due to spontaneous abortion, premature rupture of the membrane, and termination due to anomaly; no other complications occurred. No statistical difference was found between the successful pregnancy rate and the measured clinical variables.

CONCLUSIONS

The modified LTCC is feasible and safer than traditional LTCC.

The relationship between the intensity of intra-amniotic inflammation and the presence and severity of acute histologic chorioamnionitis in preterm gestation

OBJECTIVE

Acute histologic chorioamnionitis (HCA) is associated with an increased risk of perinatal mortality and morbidity. The purpose of this study was to determine the relationship between the intensity of intra-amniotic inflammation (IAI) and the severity of acute HCA in preterm gestation.

METHODS

The relationship between the intensity of IAI and the presence and severity of acute HCA was examined in 412 patients with singleton gestations who delivered within 120 h of transabdominal amniocentesis. The concentration of amniotic fluid (AF) matrix metalloproteinase (MMP)-8 was assayed to determine the presence and intensity of IAI. Acute HCA was defined as the presence of inflammatory change in any tissue samples according to the criteria previously reported. The total grade of acute HCA was used to determine the severity of HCA.

RESULTS

(1) Patients with IAI had a significantly higher rate of acute HCA than those without IAI [76.9% (133/173)] versus 20.9% (50/239), p < 0.001]. The AF MMP-8 concentration was significantly higher in patients with acute HCA than in those without acute HCA (median [range]; 188.3 ng/ml [0.3-6142.6] versus 1.8 ng/ml [0.3-2845.5], p < 0.001); (2) Of 183 patients with acute HCA, the AF MMP-8 concentration was positively correlated with the severity of acute HCA (p < 0.001).

CONCLUSIONS

AF MMP-8 concentration was not only a predictor of the presence of acute HCA, but its concentration also correlated with the severity of acute HCA. The higher the intensity of IAI, the worse the degree of acute HCA in preterm gestation.

The composition and stability of the vaginal microbiota of normal pregnant women is different from that of non-pregnant women

BACKGROUND

This study was undertaken to characterize the vaginal microbiota throughout normal human pregnancy using sequence-based techniques. We compared the vaginal microbial composition of non-pregnant patients with a group of pregnant women who delivered at term.

RESULTS

A retrospective case-control longitudinal study was designed and included non-pregnant women (n = 32) and pregnant women who delivered at term (38 to 42 weeks) without complications (n = 22). Serial samples of vaginal fluid were collected from both non-pregnant and pregnant patients. A 16S rRNA gene sequence-based survey was conducted using pyrosequencing to characterize the structure and stability of the vaginal microbiota. Linear mixed effects models and generalized estimating equations were used to identify the phylotypes whose relative abundance was different between the two study groups. The vaginal microbiota of normal pregnant women was different from that of non-pregnant women (higher abundance of Lactobacillus vaginalis, L. crispatus, L. gasseri and L. jensenii and lower abundance of 22 other phylotypes in pregnant women). Bacterial community state type (CST) IV-B or CST IV-A characterized by high relative abundance of species of genus Atopobium as well as the presence of Prevotella, Sneathia, Gardnerella, Ruminococcaceae, Parvimonas, Mobiluncus and other taxa previously shown to be associated with bacterial vaginosis were less frequent in normal pregnancy. The stability of the vaginal microbiota of pregnant women was higher than that of non-pregnant women; however, during normal pregnancy, bacterial communities shift almost exclusively from one CST dominated by Lactobacillus spp. to another CST dominated by Lactobacillus spp.

CONCLUSION

We report the first longitudinal study of the vaginal microbiota in normal pregnancy. Differences in the composition and stability of the microbial community between pregnant and non-pregnant women were observed. Lactobacillus spp. were the predominant members of the microbial community in normal pregnancy. These results can serve as the basis to study the relationship between the vaginal microbiome and adverse pregnancy outcomes.

[Transabdominal cervico-isthmic cerclage: 13 cases at Rouen University Hospital]

OBJECTIVE

The aim of this study was to describe our experience with cervico-isthmic cerclage by abdominal approach and to assess this efficacy.

PATIENTS AND METHODS

A retrospective analysis of 13 transabdominal cerclages (eight by laparotomy and five by laparoscopy), seven cases performed before pregnancy and six cases between 12 and 14 weeks of gestation, between 2004 and 2009. We analyzed the previous obstetric accidents, the etiology of cervical incompetence and the patient outcome after cerclage.

RESULTS

Median age of the patients was 35 years [27-42 years]. Patients had an average of pregnancy 4,2 [1-7], with 3,3 previous fetal losses or preterm delivery. Eighty percent had a prior failed transvaginal cerclage. The mean operative time of laparotomic cerclage was 100 minutes and 94 minutes by laparoscopy, with a mean hospitalization time respectively of seven and 2,5 days. No operative complication was reported. Eleven women were pregnant after cervico-isthmic cerclage: nine deliveries by caesarean section at term, and two preterm births between 34 and 37 weeks of gestation. Two patients are looking for being pregnant and one of those is currently doing a procedure of IVF.

DISCUSSION AND CONCLUSION

Transabdominal cervico-isthmic cerclage is an alternative technique for the management of cervical incompetence after failed vaginal cerclage. Our data indicated that the cervico-isthmic cerclage placed laparoscopically compares favorably with the laparotomy approach in regard to operative technique and risk of complications.

The occurrence of preterm delivery is linked to pregnancy-specific distress and elevated inflammatory markers across gestation

There is mounting evidence that stress during pregnancy can have detrimental effects on gestation and birth. Existing studies indicate that prenatal stress may increase levels of circulating inflammatory markers that are associated with prematurity and pregnancy complications, suggesting that stress-related changes in the cytokine milieu may increase the risk of poor pregnancy outcome. Previous studies, however, have not clearly connected stress during pregnancy to changes in inflammatory mediators and, in turn, to clinically-relevant outcomes such as premature delivery. The present study sought to directly connect prenatal stress and changes in inflammatory markers to preterm delivery and gestational age at birth (GAB). A sample of 173 women was recruited during the first trimester of pregnancy and followed through delivery. Overall stress, pregnancy-specific distress, and inflammatory markers were assessed early and later in pregnancy, and the predictive value of these measures for preterm birth and GAB was determined. There were significant differences in pregnancy-specific distress, IL-6, and TNF-α between women who delivered prematurely versus those who delivered at term, and elevated levels of pregnancy-specific distress, IL-6, and TNF-α were predictive of shortened GAB overall. Importantly, in many cases, the effects of overall stress and pregnancy-specific distress on GAB were mediated by levels of circulating inflammatory markers. Collectively, these data provide strong evidence that prenatal stress experiences can affect the timing of parturition via alterations in circulating inflammatory mediators, and underscore the need for ongoing research aimed at further understanding the mechanisms and effects of prenatal stress on maternal and infant health.

Periodontal disease and systemic health: current status

The relationship between poor oral health and systemic diseases has been increasingly recognized over the past two decades. Indeed, the clichés "You cannot have good general health without good oral health", "The mouth is part of the body" and "Floss or die", are gaining an increasing momentum. A large number of epidemiological studies have now linked poor oral health with cardiovascular diseases, poor glycaemic control in diabetics, low birthweight preterm babies and a variety of other conditions. The majority have shown an association, although not always strong. As a result, a number of meta-analyses have been conducted and have confirmed the associations and at the same time cautioned that further studies are required, particularly with regard to the effect of periodontal treatment in reducing risk. A number of biologically plausible mechanisms have been put forward to explain the association and there is accumulating evidence in support of them, although at this stage, insufficient to establish causality. Nevertheless, the relationship between poor oral health and systemic diseases has become a significant issue, such that adult oral health can no longer be ignored in overall health strategies. This review provides an update on current understanding of the contribution of poor oral health to systemic diseases, the possible mechanisms involved and the relevance of this for general dental practitioners.

Evidence for complement activation in the amniotic fluid of women with spontaneous preterm labor and intra-amniotic infection

OBJECTIVE

The complement system plays an important role in host defense against infection. Concentrations of complement split products or anaphylatoxins (C3a, C4a, and C5a) in biological fluids are considered to reflect complement activation. The purpose of this study was to determine if term and preterm parturition are associated with evidence of complement activation in the amniotic fluid.

STUDY DESIGN

Amniotic fluid (AF) samples were collected from 270 women in the following groups: (1) normal pregnant women in midtrimester (n = 70), (2) term not in labor (n = 23), (3) term in labor (n = 48), and (4) preterm labor (PTL) (n = 129). PTL was categorized into: (a) PTL without microbial invasion of the amniotic cavity (MIAC) who delivered at term (n = 42), (b) PTL who delivered preterm without MIAC (n = 57), and (c) PTL with MIAC (n = 30). C5a, C4a, and C3a concentrations in amniotic fluid were determined by ELISA. Nonparametric tests were used for statistical analysis.

RESULTS

(1) The median AF C5a concentration was higher in women at term than that of those in the midtrimester (p = 0.02); (2) Spontaneous labor at term was not associated with changes in AF concentrations of anaphylatoxins C3a, C4a, and C5a (all p > 0.05); (3) Among patients with PTL who delivered preterm, those with MIAC had higher AF C4a and C5a concentrations than those without infection (p < 0.01); and (4) AF C3a, C4a, and C5a concentrations were higher in patients with PTL with MIAC than in those with PTL without MIAC who delivered at term.

CONCLUSION

Patients with spontaneous preterm labor and intact membranes with microbial invasion of the amniotic cavity had higher median amniotic fluid concentration of complement split products C3a, C4a, and C5a than patients without intra-amniotic infection. These findings suggest that preterm labor in the context of infection is associated with activation of the complement system.

Cerclage par voie abdominale pour la prise en charge des incompétences cervicales chez les femmes à haut risque

OBJECTIVES

Transabdominal cervico-isthmic cerclage is an alternative to vaginal route for patients with severe cervical incompetence. The purpose of this study is to describe our experience with this technique during pregnancy for high risk women.

MATERIALS AND METHODS

We performed a retrospective study including 12 transabdominal cerclages performed between 1988 and 2005. All patients had an history of repeated midtrimester fetal losses or preterm delivery, and 82% already had a prior failed transvaginal cerclage. Fourteen pregnancies were reported.

RESULTS

The median gestational age at cerclage placement was 14 weeks (range: 12 to 17). All patients underwent a caesarean section at a mean gestational age of 35 weeks gestation (range: 23 to 38 WG). The fetal survival rate was 93 compared to 17% before the cerclage. There were no significant perioperative or neonatal complications.

CONCLUSION

Transabdominal cervico-isthmic cerclage remains a reliable technique for the management of cervical incompetence after a prior failed transvaginal cerclage when vaginal access is difficult. Laparoscopic approach is under development.

Management of Cervical Insufficiency and Bulging Fetal Membranes

OBJECTIVE

To evaluate the efficacy of emergency cerclage in cases with dilated cervix and protruding fetal membranes in a group of women considered at low risk for preterm delivery by their obstetric histories.

METHODS

All cases of cervical dilatation and bulging membranes were detected through a transvaginal ultrasonographic screening for preterm delivery between 18 and 26 weeks during a 6-year study period. Twenty-nine women underwent an emergency cervical cerclage and composed the cerclage group, whereas 17 others refused and formed the bed rest group. All patients were given antibiotics and prophylactic tocolysis.

RESULTS

The mean prolongation of pregnancy (8.8 weeks) and the mean birth weight (2,101 g) after cerclage placement differed significantly from those of the bed rest group (3.1 weeks and 739 g, respectively). Twenty-five of the 29 pregnancies in the cerclage group ended in live birth, compared with 7 of the 17 pregnancies in the bed rest group (P = .001) (relative risk [RR] 0.33, 95% confidence interval [CI] 0.11-0.98). Neonatal survival was 96% in the cerclage group and 57.1% in the bed rest group (P = .025) (RR 0.09, 95% CI 0.01-0.76). The preterm delivery rate less than 32 weeks was 31% and 94.1% in the cerclage and the bed rest groups, respectively (P < .001) (RR 0.33, 95% CI 0.19-0.57), whereas the admission to neonatal intensive care unit was 28% and 85.7% in the 2 groups, respectively, (P = .01) (RR 0.33, 95% CI 0.16-0.66).

CONCLUSION

Emergency cervical cerclage can be accomplished safely in women with dilated cervix and bulging membranes. It can reduce preterm delivery before 32 weeks and improve neonatal survival compared with bed rest.

LEVEL OF EVIDENCE

II-1.

Immunological properties of human decidual macrophages--a possible role in intrauterine immunity

Our aim was to investigate the contribution of decidual macrophages, which constitute an important immune component of the decidua in late gestation, to intrauterine defence mechanisms. Using flow cytometry we examined the ability of decidual macrophages, isolated from term decidua, to bind and phagocytose fluorescence-labelled bacterial and yeast bioparticles. We also assessed their ability to generate superoxide radicals and tumour necrosis factor-alpha following lipopolysaccharide challenge. Decidual macrophages bound bacterial and yeast particles in a dose-dependent manner, which subsequently led to phagocytosis. These macrophages also produced superoxide radicals and the pro-inflammatory cytokine TNF-alpha when challenged with bacterial lipopolysaccharides. These results suggest a role for decidual macrophages in pathogen recognition and clearance during pregnancy, and, therefore, they are likely to protect the fetus against intrauterine infections which might otherwise lead to preterm labour.

Prenatal stress alters cytokine levels in a manner that may endanger human pregnancy

OBJECTIVE

Recent data suggest that prenatal stress negatively affects pregnancy and infant outcome. Existing studies implicate dysregulation of the immune and endocrine systems in stress-related increases in premature labor and poor birth outcome, but no published studies have directly addressed the relationships among these variables during pregnancy. We sought to test the hypothesis that high levels of psychosocial stress and low levels of social support during pregnancy alter maternal cytokine profiles in a manner that contributes to poor birth outcomes.

METHODS

Psychosocial stress and social support were measured in 24 women with overtly normal pregnancies once during each trimester of pregnancy. Levels of interleukin-10 (IL-10), IL-6, and tumor necrosis factor-alpha (TNF-alpha) were assessed concurrently with stress and support measurements.

RESULTS

High social support was associated with low stress scores. Elevated stress scores were positively correlated with higher levels of the proinflammatory cytokines IL-6 and TNF-alpha, and with low levels of the antiinflammatory cytokine IL-10.

CONCLUSIONS

These findings provide initial support for our hypothesis that stress-related neural immune interactions may contribute to pregnancy complications and poor outcome, but require further study to determine the mechanism and significance of these effects.

Periodontal Diseases and the Risk of Preterm Birth and Low Birth Weight: A Meta-Analysis

BACKGROUND

This meta-analysis of periodontal disease in relation to the risk of preterm birth/low birth weight (PTB/ LBW) is based on two case-control studies and three prospective cohort studies that met pre-stated inclusion criteria.

METHODS

Information on the designs of the studies, characteristics of the study population, exposure and outcome measures, control for confounders, and risk estimates were abstracted independently by two investigators using a standard protocol.

RESULTS

Pregnant women with periodontal disease had an overall adjusted risk of preterm birth that was 4.28 (95% confidence interval [CI], 2.62 to 6.99; P <0.005) times that risk for healthy subjects. The overall adjusted odds ratio of preterm low birth weight was 5.28 (95% CI, 2.21 to 12.62; P <0.005), while the overall adjusted odds ratio of a delivery of either PTB or LBW was 2.30 (95% CI, 1.21 to 4.38; P <0.005).

CONCLUSIONS

Our findings indicate that periodontal diseases in the pregnant mother significantly increase the risk of subsequent preterm birth or low birth weight. While it remains important to promote good oral hygiene during routine prenatal visits, there is no convincing evidence, on the basis of existing case control and prospective studies, that treatment of periodontal disease will reduce the risk of preterm birth. Consequently, large randomized, placebo-controlled, masked clinical trials are required.

N-acetylcysteine prevents endotoxin-induced degeneration of oligodendrocyte progenitors and hypomyelination in developing rat brain

Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by diffuse white matter injury and is associated with cerebral palsy (CP). Maternal and placental infections are major causes of prematurity and identifiable etiology of PVL and CP. Here we have evaluated the therapeutic efficacy of N-acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, to attenuate lipopolysaccharide (LPS)-induced white matter injury and hypomyelination in the developing rat brain, an animal model of PVL. Intraperitoneal pretreatment of pregnant female rats with NAC (50 mg/kg), 2 hr prior to administration of LPS at embryonic day 18 (E18), attenuated the LPS-induced expression of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1beta, and inducible nitric oxide synthase in fetal rat brains. There were significantly reduced numbers of TUNEL(+) nuclei coimmunostained for platelet-derived growth factor-alphaR(+) [a surface marker for oligodendrocyte progenitor cells (OPCs)] at E20 in the subventricular zone of fetal rat brain in the NAC + LPS group compared with the untreated LPS group. Interestingly, immunostaining for O4 and O1 as markers for late OPCs and immature oligodendrocytes demonstrated fewer O4(+) and O1(+) cells in the LPS group compared with the NAC + LPS and control groups. Consistent with O4(+)/O1(+) cell counts, the expression of myelin proteins such as myelin basic protein, proteolipid protein, and 2'3'-cyclic nucleotide phosphodiesterase, including transcription factors such as MyT1 and Gtx, was less in the LPS group at late postnatal days, indicating severe hypomyelination in the developing rat brain when compared with NAC + LPS and control groups. Collectively, these data support the hypothesis that NAC may provide neuroprotection and attenuate the degeneration of OPCs against LPS evoked inflammatory response and white matter injury in developing rat brain. Moreover, these data suggest the possible use of NAC as a treatment for pregnant women with maternal or placental infection as a means of minimizing the risk of PVL and CP.

The vaginal inflammatory milieu and the risk of early premature preterm rupture of membranes

OBJECTIVE

The purpose of this study was to determine the association of vaginal pH > or =5.0 and vaginal neutrophils >5 per oil field with preterm rupture of membranes (PPROM).

STUDY DESIGN

This was a secondary analysis of the Vaginal Infections and Prematurity cohort, and was comprised of 12,734 evaluable women enrolled between 23 and 26 weeks' gestation. Women were tested for sexually transmitted infections and vaginal pH. Gram-stained smears were used for the detection of neutrophils.

RESULTS

In this analysis, 5751 (41.3%) women had neutrophils >5 per oil field, and 2500 (18.0%) had pH > or =5.0. Both elevated pH and neutrophils were present in 1149 women (8.3%). The concomitant presence of both neutrophils and elevated pH was significantly associated with PPROM at 24 to 32 weeks.

CONCLUSION

Elevated vaginal pH and neutrophils are most strongly associated with early third-trimester PPROM, reflecting the importance of infection and/or inflammation in the pathogenesis of this condition.

An Evidence-Based Approach to the Evaluation and Treatment of Premature Rupture of Membranes: Part I

Preterm premature rupture of membranes (PPROM) occurs in 3% of pregnancies and is responsible for one third of all preterm births. PPROM will affect 120,000 women in the United States each year. It is associated with significant maternal, fetal, and neonatal morbidity and mortality resulting from infection, umbilical cord compression, abruptio placentae, and prematurity. The etiology is multifactorial, but the most significant risk factors are previous preterm birth and previous preterm premature rupture of membranes. Accurate diagnosis is extremely important to assure proper treatment. Evaluation is based on patient history and clinical examination. This review presents the available evidence and grades it according to the U.S. Preventative Task Force recommendations. In part I of this review, the definition, pathophysiology, and methods of PPROM diagnosis are presented. In part II, the management, treatment, neonatal outcome, and the maternal and fetal evaluation of women with PPROM in the presence of cerclage and medical complications is reviewed.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to define the term: preterm premature rupture of membranes, to list the factors associated with premature rupture of membranes, and to outline the tests available for the diagnosis of intra-amniotic infection.

Lipopolysaccharide induces nitric oxide synthase expression and platelet-activating factor increases nitric oxide production in human fetal membranes in culture

BACKGROUND

Platelet-activating factor and nitric oxide may be involved in the initiation of human labour as inflammatory mediators. The aim of this study was to test whether platelet-activating factor and lipopolysaccharide were able to induce nitric oxide synthase expression and stimulate the production of nitric oxide in human fetal membrane explants in culture.

METHODS

Fetal membranes were collected from Caesarean sections at term. RNA was extracted from membranes and subjected to a qualitative RT-PCR to assess the baseline expression of iNOS. Discs of fetal membranes were cultured for 24 hours in the presence of platelet-activating factor at a dose range of 0.1 nanomolar--1 micomolar or 1 microgram/ml lipopolysaccharide. Nitric oxide production was measured via nitrite ions in the culture medium and mRNA for iNOS was detected by RT-PCR.

RESULTS

Culturing the membrane discs in medium containing serum induced nitric oxide synthase expression and platelet-activating factor significantly stimulated the production of nitric oxide under these conditions. When cultured without serum inducible nitric oxide synthase expression was induced by lipopolysaccharide, but not by platelet-activating factor.

CONCLUSION

Platelet-activating factor may have a role in the initiation of labour, at term or preterm, via the increased local production of nitric oxide as an inflammatory mediator. In this model of intrauterine infection, lipopolysaccharide was found to induce iNOS expression by fetal membranes, and this mechanism could be involved in preterm labour.

Quantitative microbiologic models for preterm delivery

Preterm delivery (PTD) is the leading cause of infant morbidity and mortality in the United States. An epidemiological association between PTD and various bacteria that are part of the vaginal microflora has been reported. No single bacterial species has been identified as being causally associated with PTD, suggesting a multifactorial etiology. Quantitative microbiologic cultures have been used previously to define normal vaginal microflora in a predictive model. These techniques have been applied to vaginal swab cultures from pregnant women in an effort to develop predictive microbiologic models for PTD. Logistic regression analysis with microbiologic information was performed for various risk groups, and the probability of a PTD was calculated for each subject. Four predictive models were generated by using the quantitative microbiologic data. The area under the curve (AUC) for the receiver operating curves ranged from 0.74 to 0.94, with confidence intervals (CI) ranging from 0.62 to 1. The model for the previous PTD risk group with the highest percentage of PTDs had an AUC of 0.91 (CI, 0.79 to 1). It may be possible to predict PTD by using microbiologic risk factors measured once the gestation period has reached the 20-week time point.

High altitude residence during pregnancy alters cytokine and catecholamine levels

This study assessed the impact of high altitude residence during pregnancy on parameters of maternal immune and endocrine system function. Urinary catecholamines, and serum cytokines, estriol, and cortisol were assessed during pregnancy in women living at moderate or high altitude. Women residing at high altitude exhibited elevated levels of proinflammatory cytokines only during pregnancy, and tended to have higher levels of catecholamines during pregnancy than women living at lower altitude. These data suggest that the combination of high altitude and pregnancy alters the maternal neural-immune axis in a manner that may predispose women to suboptimal birth outcomes.

C-reactive protein: a serological marker for preterm delivery?

BACKGROUND

We studied the association between the C-reactive protein level in the maternal serum early in the second trimester with that in preterm delivery.

METHODS

The present study is a prospective nested case-control study including 84 singleton, preterm deliveries (cases) and 400 singleton, term deliveries (controls), based at the Odense University Hospital, Denmark. These cases were identified from a cohort of 2846 women, monitored from their first prenatal care visit until their delivery. All the participants were examined at enrollment (median 16.3 weeks of gestation). Conventional statistical methods were used for analyses.

RESULTS

We found statistically significant differences in the C-reactive protein levels measured in early pregnancy between the women delivering preterm and those delivering at term. Different statistically significant odds ratios of between 1.7 and 2.0 were calculated, depending on the C-reactive protein level's cut-off value, and ranged from 5.6 mg/l (75th percentile) to 16.4 mg/l (95th percentile). The highest level was achieved at the 85th percentile (7.6 mg/l); odds ratio 2.0 (95%CI, 1.2-3.5).

CONCLUSION

A high C-reactive protein level at the beginning of a pregnancy is associated with a nearly twofold increased risk of preterm delivery; however, the clinical value at this point is still limited.

An in vitro study of antibacterial properties of the cervical mucus plug in pregnancy

OBJECTIVE

To evaluate whether cervical mucus plugs are antibacterial in vitro.

STUDY DESIGN

Cervical mucus plugs from 56 healthy women in labor were studied by 2 different antimicrobial assays: (1) analysis of the inhibition by the cervical mucus plug of several gram-positive and gram-negative bacteria by overlaying the cervical mucus plug onto an agar plate with imbedded bacteria, and (2) determination of the antibacterial property of the cervical mucus plug material by radial diffusion assay with group B Streptococcus and Escherichia coli.

RESULTS

In the agar overlay assay, there was complete inhibition of clinical isolates of Staphylococcus saprophyticus, E coli, and Pseudomonas aeruginosa and patient-variable partial-to-complete inhibition of Enterococcus faecium, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus agalactiae. In the radial diffusion assay, cervical mucus plugs had activity toward group B Streptococcus equivalent to 0.075 microg/mL of gentamicin and toward E coli equivalent to 0.5 microg/mL of gentamicin.

CONCLUSION

A low-molecular substance with antibacterial activity in the cervical mucus plug may protect the fetus against ascending infections.

Maternal urinary tract infection alters water maze performance in the offspring

The effects of maternal urinary tract infection (UTI) or endotoxin exposure on fetal outcome in rats were investigated. Prior to conception, dams of the UTI group were water-deprived and anesthetized. The urinary tract was then catheterized and injected with 0.2 of 1 x 10(9) Escherichia coli. The endotoxin group was injected with 0.03 mg/kg lipopolysaccharide on the fourth day of gestation and then every third day thereafter. The control groups were treated in the same manner, with the exception that the infection control was not catheterized or injected with E. coli, and the endotoxin control was not exposed to lipopolysaccharide. A nontreated control group was weighed daily. Beginning on postnatal day (PD) 19, offspring were tested daily in a water maze spatial navigation task. The retention latencies (Sessions 7--10) revealed deficits in the infection and endotoxin groups. In the rat model, these findings suggest that exposure during gestation to a maternal immune challenge may result in adverse fetal outcome.

Periodontal infections and pre-term birth: early findings from a cohort of young minority women in New York

The aim of this report is to provide early data from an ongoing study examining (i) the relationship between periodontal infections and pre-term low birth weight (PLBW) in a cohort of young, minority, pregnant and post-partum women; and (ii) the effect of periodontal interventions on pregnancy outcome. During the first 2 yr of the study, 213 women were enrolled and examined clinically for dental plaque, calculus, bleeding on probing, and probing depth. Birth outcome data were available for 164 women, including one group (n = 74) subjected to oral prophylaxis during pregnancy, and a second group (n=90) who received no prenatal periodontal treatment. Subgingival plaque samples were available from 145 subjects (4 samples/subject) and were analyzed by checkerboard DNA hybridization with respect to 12 bacterial species. The prevalence of PLBW was 16.5% (27 cases) in this cohort. No differences in clinical periodontal status were observed between PLBW cases and women with normal birth outcome. However, PLBW mothers had significantly higher levels of Bacteroides forsythus and Campylobacter rectus, and consistently elevated counts for the other species examined. PLBW occurred in 18.9% of the women who did not receive periodontal intervention (17 cases), and in 13.5% (10 cases) of those who received such therapy.

Prophylactic administration of clindamycin 2% vaginal cream to reduce the incidence of spontaneous preterm birth in women with an increased recurrence risk: a randomised placebo-controlled double-blind trial

OBJECTIVE

To test the hypothesis that prophylactic administration of clindamycin 2% vaginal cream can reduce the incidence of preterm birth in a high risk population.

DESIGN

A multi-centre, randomised, double-blind, placebo-controlled trial.

SETTING

Twelve city hospitals in The Netherlands.

PARTICIPANTS

One hundred and sixty-eight women with a singleton pregnancy and a history of a spontaneous preterm delivery in the preceding pregnancy.

INTERVENTIONS

Clindamycin 2% vaginal cream, or placebo cream, administered daily for seven days at 26 and 32 weeks of gestation.

MAIN OUTCOME MEASURES

Spontaneous preterm birth at < 37 weeks, admission for threatened preterm labour, neonatal infectious morbidity.

RESULTS

In the intention-to-treat analysis no difference was found in overall preterm birth between clindamycin and placebo (23% vs 18%, respectively). In the subgroup who completed the trial and administered all medication, more women delivered before 34 weeks in the clindamycin group (1.4% in the placebo vs 9.0% in the clindamycin group; P < 0.05). The length of admissions for threatened preterm labour did not differ. More infectious neonatal morbidity was seen in the clindamycin group (5/83 vs 0/85; P < 0.05).

CONCLUSION

Clindamycin 2% vaginal cream given prophylactically to women with a spontaneous preterm birth in the preceding pregnancy did not prevent preterm delivery or reduce the number of admissions for threatened preterm labour. The neonatal infectious morbidity in the group treated with clindamycin was significantly higher and a major concern.

The effects of Escherichia coli STa (heat stable) toxin on the contractility of isolated human myometrium in vitro

OBJECTIVE

The purpose of the study was to assess the effects of Escherichia coli STa (heat stable) toxin on isolated human myometrial response to oxytocin.

METHODS

One hundred and sixteen muscle strips were obtained from the lower uterine segment of 42 women undergoing cesarean section at term. Amniotic membranes and decidua were excluded. Uterine contractility in response to cumulative doses of E. coli STa toxin was recorded, as well as uterine response to cumulative doses of oxytocin before and after incubation with STa toxin or vehicle. The 50th percentile effective oxytocin concentration (EC50) of muscle strips with and without spontaneous activity before and after the incubation with STa toxin or vehicle was calculated. A paired t test was used for comparison.

RESULTS

Muscle strips with and without spontaneous activity responded to cumulative doses of oxytocin before and after the incubation with STa toxin or vehicle. No differences in contraction force, duration, or frequency were noted between the groups (P > 0.05). Furthermore, this toxin was not able to induce uterine contractility when tested alone.

CONCLUSIONS

The inability of this toxin to affect myometrial response to oxytocin in this study may be due to the absence of amnion cells, chorion, or decidua. Other possible explanations for the lack of response are discussed.

The effect of monophosphoryl lipid A on lipopolysaccharide-induced prostaglandin E2 release in human choriodecidua

The aim of this study was to determine the effect of an inhibitor of bacterial endotoxin, monophosphoryl lipid A (MLA), on lipopolysaccharide (LPS)-induced prostaglandin E2 (PGE2) formation by human choriodecidua explants incubated in vitro. LPS induced the release of PGE2 from explants in a time-and dose-dependent manner (P < 0.05, n = 5), thus establishing the efficacy of the experimental model. MLA at concentrations of 10 micrograms/ml also increased PGE2 release from explants when compared to vehicle controls (P < 0.05, n = 5). When used at a concentration that did not stimulate PGE2 release (1 microgram/ml), MLA pretreatment, coincubation or a combination of these protocols did not significantly affect LPS-induced PGE2 release. These data establish that MLA does not act by abrogating tissue LPS responsiveness. Under the conditions utilized in this study, MLA acts locally as a low potency 'LPS-like agent'. The previously reported in vivo efficacy of systemically administered MLA may involve the partial depletion or down regulation of LPS response pathways and the subsequent development of LPS tolerance.

Maternal plasma fibronectin: a predictor of preterm delivery

OBJECTIVE

Current opinion holds that there are several distinct groups among patients with preterm labour: one of them is characterized by bacterial infection, another one by the presence of placental vascular abnormalities with endothelial damage. The aim of this study was to investigate plasma fibronectin, a suspected biochemical marker of endothelial damage, as an indicator for pregnancies with a high risk of preterm delivery.

METHODS

Plasma fibronectin levels were measured in patients with preterm labour (n = 80) and in healthy pregnant women with uncomplicated (control) pregnancies (n = 64) between the 22nd and 36th week of gestation. Furthermore, the plasma concentrations of fibronectin in 15 newborns at term and ten babies born preterm were measured to study the relationship between preterm delivery and plasma fibronectin concentration in newborns. Fibronectin was measured by nephelometry.

RESULTS

The mean concentration of fibronectin in patients with preterm labour was 0.44 g/l (S.D., 0.15) vs. 0.25 g/l (S.D., 0.12) in uncomplicated control pregnancies matched for gestational age. In control patients who actually delivered at term, fibronectin values were found to be lower than in control patients who underwent preterm delivery (0.25 g/l; S.D., 0.05; vs. 0.46 g/l; S.D., 0.15; P < 0.05). Particularly high values were detected in patients with preterm labour delivering before 32 weeks of gestation (0.60 g/l; S.D., 0.16). There was no significant difference between fibronectin concentrations in the umbilical arterial and venous blood of premature infants and mature infants. Leucocyte concentration, bacteriological smear and cervical dilatation did not correlate with fibronectin concentrations in patients with preterm delivery or controls.

CONCLUSION

We conclude that the higher plasma concentrations of fibronectin in women with preterm labour may be a biochemical marker and a predictor of preterm delivery.

A longitudinal study of bacterial vaginosis during pregnancy

OBJECTIVE

To determine the longitudinal changes in the incidence of vaginosis in pregnancy.

DESIGN

A prospective study of women during pregnancy.

SETTING

A District General Hospital in North-West London.

SUBJECTS

Seven hundred and eighteen pregnant women attending antenatal clinics. At their first attendance and subsequently, Gram-stained vaginal smears were examined and Mycoplasma hominis and Gardnerella vaginalis were sought by culture.

RESULTS

Initially, 87 (12%) women had bacterial vaginosis diagnosed on Gram-stained reading of the vaginal smears. Examination of further smears, obtained from 176 women at 36 weeks of gestation, showed that those whose vaginal flora was normal initially, and who went to term, rarely developed vaginosis (three of 127, 2.4%). Samples were obtained at 36 weeks gestation from 32 women who had bacterial vaginosis initially, and went to term. In almost 50% (15 of 32) of these a normal lactobacillus-dominated flora had regenerated. Thirty-five women (5%) had initial vaginal smears graded as intermediate. From this group, six of the 17 (35%) women from whom samples were obtained at 36 weeks gestation still had flora of an intermediate pattern; 10(59%) now had normal flora and only one (6%) had developed bacterial vaginosis. Women with bacterial vaginosis were more likely to be culture-positive for M. hominis than those with normal flora (34/78 versus 10/563, odds ratio 42.73 (18.9 to 102.3) P < 0.001), or to be culture-positive for G. vaginalis than those with normal flora (35/78 versus 21/563, odds ratio 21.0 (10.75 to 41.2) P < 0.001).

CONCLUSION

Pregnant women do not commonly develop bacterial vaginosis after 16 weeks gestation, and if present, it remits spontaneously in approximately half of those who reach term. As bacterial vaginosis is associated with increased rates of second trimester miscarriage and preterm delivery, any treatment aimed at its eradication in pregnancy should be given no later than the beginning of the second trimester of pregnancy.

Cytokine levels in amniotic fluid and inflammatory changes in the placenta from normal deliveries at term

Cytokine levels in amniotic fluid have been shown to increase towards term in normal pregnancies, and may play a regulatory role in parturition by stimulating the local production of prostaglandins. The work reported in the present paper was conducted in order to test the hypothesis that the increased cytokine levels may be induced by a subclinical inflammatory reaction in intrauterine tissues. The concentrations of tumor necrosis factor (TNF), interleukin 1 (IL-1), interleukin 2 (IL-2) and interleukin 6 (IL-6) were determined in samples of amniotic fluid from 38 women in delivery at term, after a clinically normal pregnancy. In 33 of the cases, tissue material was available for histological examination. In these, the extent of inflammatory cell infiltration was assessed in the fetal membranes, placenta and umbilical cord. A close interrelation was observed between the levels of the mediators typically released during inflammatory processes (TNF, IL-1, IL-6). Frank chorioamnionitis was not found in any of the histological specimens, although most placentae showed varying degrees of granulocyte infiltration in the fibrin layer under the chorion, sometimes also in the chorionic membrane. The degree of such leukocytic infiltration correlated positively with the levels of TNF, IL-1 and IL-6. These findings lend support to the hypothesis that a low-level inflammatory process may be a normal occurrence in the term placenta, and that this process may induce the production of cytokines, which, in turn, may play a role in the regulation of parturition. Such inflammation could be due to exposure of the fetal membranes to microbial material from the vagina, as the cervix dilates towards term.

Abnormal bacterial colonisation of the genital tract and subsequent preterm delivery and late miscarriage

OBJECTIVE

To find out whether women with bacterial vaginosis detected early in pregnancy are at increased risk of preterm delivery.

DESIGN

Prospective description cohort study.

SETTING

Antenatal clinic in a district general hospital.

SUBJECTS

783 women examined during their first antenatal clinic visit and screened for recognised risk factors for preterm delivery and the presence of bacterial vaginosis or intermediate abnormal flora detected by examination of a vaginal smear stained by Gram's method.

MAIN OUTCOME MEASURES

Gestational age at delivery classified as late miscarriage (16-24 weeks' gestation), preterm delivery (24-37 weeks' gestation), term delivery (> or = 37 weeks' gestation).

RESULTS

Multiple logistic analysis showed that there was an increased incidence of preterm delivery in women with a previous preterm delivery (9/24; odds ratio 25; 95% confidence interval 9 to 70; P < 0.001) and bacterial vaginosis (9/115; 2.8; 1.1 to 7.4; P = 0.04). A further logistic analysis of data from women recruited before 16 weeks' gestation showed that preterm deliveries or late miscarriages occurred more often in women with bacterial vaginosis (12/77; 5.5; 2.3 to 13.3; P < 0.001).

CONCLUSIONS

Late miscarriage and preterm delivery are associated with the presence of bacterial vaginosis in early pregnancy. This is independent of recognised risk factors such as previous preterm delivery.

Endotoxin-induced fetal growth retardation in the pregnant guinea pig

OBJECTIVES

Our purpose was to test the hypothesis that bacterial endotoxin may reduce fetal growth and to assess some of the pathophysiologic mechanisms of such an effect.

STUDY DESIGN

Two randomly selected groups of nine guinea pigs at 30 days' gestation were treated with a solution of endotoxin isolated from Bacteroides fragilis or with solvent alone. Antibody titers, glucose, triglycerides, and 6-keto-prostaglandin F1 alpha were determined in maternal or fetal blood samples. Fetal weight was determined at 61 days' gestation.

RESULTS

Endotoxin-treated guinea pigs showed positive antiendotoxin antibody titers, reduced weight gain, and significantly higher serum levels of triglycerides and 6-keto-prostaglandin F1 alpha, but not of glucose, than did sham-treated controls. Fetuses of endotoxin-treated animals had significantly lower birth weights and serum glucose concentrations and significantly higher triglyceride levels than did control fetuses.

CONCLUSIONS

Bacteroides fragilis endotoxin causes fetal growth retardation in the pregnant guinea pig, which may be due to alterations in carbohydrate and fat metabolism mediated by cytokine action.

Localization of tumour necrosis factor production in cells at the materno/fetal interface in human pregnancy

Biologically active tumour necrosis factor (TNF) was detected in medium conditioned by incubation with explants of human pregnancy decidua or fetal chorionic villous tissue, taken in the first trimester and at term. Addition of endotoxin increased TNF release in most cases. ELISA assays gave similar results for TNF-alpha and also demonstrated low levels of TNF-beta. Using cell populations purified by flow cytometry, secretion of biologically active TNF was shown to be localized to the macrophages. Cytotrophoblast purified from term amniochorion produced no TNF. Both decidual and chorionic villous tissue at term contained mRNA for TNF-alpha and TNF-beta. TNF-alpha mRNA was confined to decidual macrophages in first trimester tissue, and was not present in chorionic cytotrophoblast. TNF-beta mRNA, in contrast, was detected in both macrophage and non-macrophage populations in term decidua.