Intrauterine inflammation and preterm delivery

The Role of C5a Receptor Signaling in Endotoxin-Induced Miscarriage and Preterm Birth

PROBLEM

Complement factor 5a (C5a), a potent pro-inflammatory mediator of the complement system, has been implicated in fetal rejection throughout gestation, from miscarriage to preterm birth. This study aimed to investigate the role of the principal C5a receptor, C5aR1 (CD88), in both miscarriage and preterm birth, in a bacterial endotoxin (lipopolysaccharide; LPS) murine model.

METHOD OF STUDY

Wild-type and C5ar1 knockout mice were administered LPS at 9.5 or 15.5 days post-conception to induce miscarriage or preterm birth, respectively.

RESULTS

C5ar1 knockout mice were protected against miscarriage in response to administration of LPS in early gestation. However, the absence of C5aR1 had no effect on the rates of preterm birth when LPS was administered in late gestation.

CONCLUSION

There may be a gestational window in which excessive activation of C5a can exert deleterious effects in pregnancy. Future strategies targeting the C5a-C5aR1 signaling axis should be considered to ameliorate miscarriages in patients with recurrent pregnancy loss.

On the significance of new biochemical markers for the diagnosis of premature labour

Preterm labour is defined as a birth taking place between 22nd and 37th weeks of gestation. Despite numerous studies on the aetiology and pathogenesis of preterm labour, its very cause still remains unclear. The importance of the cytokines and acute inflammation in preterm labour aetiology is nowadays well-proven. However, chronic inflammation as an element of the pathogenesis of premature labour is still unclear. This paper presents a literature review on the damage-associated molecular patterns (DAMPs), receptors for advanced glycation end products (RAGE), negative soluble isoforms of RAGE, chemokine-stromal cell-derived factor-1 (SDF-1) and one of the adipokines, resistin, in the pathogenesis of preterm labour. We conclude that the chronic inflammatory response can play a much more important role in the pathogenesis of preterm delivery than the acute one.

The risk of placental abruption and placenta previa in pregnant women with chronic hepatitis B viral infection: a systematic review and meta-analysis

INTRODUCTION

Several epidemiological studies have found a positive association between chronic hepatitis B virus (CHB) infection and the risk of placental abruption and placenta previa, but various studies have reported conflicting findings. The objective was to systematically review the literature to determine a possible association between CHB infection and these two placental complications.

METHODS

We conducted a computerized search in electronic database through March 1, 2014, supplemented with a manual search of reference lists, to identify original published research on placental abruption and placenta previa rates in women with CHB infection. Data were independently extracted, and relative risks were calculated. The meta-analysis was performed using Stata version 10.0 software.

RESULTS

Five studies involving 9088 placenta previa cases were identified. No significant association between CHB infection and placenta previa was identified (OR = 0.98, 95% CI = 0.60-1.62). Five studies involving 15571 placental abruption cases were identified. No significant association between CHB infection and placental abruption was identified (OR = 1.42, 95% CI, 0.93-2.15).

DISCUSSION

The immune response against the virus represents a key factor in determining infection outcomes. No observation of significant increased risk of the placental complications could be partially explained by the complex immune response during CHB infection.

CONCLUSIONS

Our meta-analysis found no evidence of significant associations between CHB infection and increased risk of placental abruption as well as placenta previa. Further well-designed studies were warranted to assess any potential association between CHB infection and increased risk of placental abruption as well as placenta previa.

Prevalence and clinical significance of sterile intra-amniotic inflammation in patients with preterm labor and intact membranes

PROBLEM

Inflammation and infection play a major role in preterm birth. The purpose of this study was to (i) determine the prevalence and clinical significance of sterile intra-amniotic inflammation and (ii) examine the relationship between amniotic fluid (AF) concentrations of high mobility group box-1 (HMGB1) and the interval from amniocentesis to delivery in patients with sterile intra-amniotic inflammation.

METHOD OF STUDY

AF samples obtained from 135 women with preterm labor and intact membranes were analyzed using cultivation techniques as well as broad-range PCR and mass spectrometry (PCR/ESI-MS). Sterile intra-amniotic inflammation was defined when patients with negative AF cultures and without evidence of microbial footprints had intra-amniotic inflammation (AF interleukin-6 ≥ 2.6 ng/mL).

RESULTS

(i) The frequency of sterile intra-amniotic inflammation was significantly greater than that of microbial-associated intra-amniotic inflammation [26% (35/135) versus 11% (15/135); (P = 0.005)], (ii) patients with sterile intra-amniotic inflammation delivered at comparable gestational ages had similar rates of acute placental inflammation and adverse neonatal outcomes as patients with microbial-associated intra-amniotic inflammation, and (iii) patients with sterile intra-amniotic inflammation and high AF concentrations of HMGB1 (≥8.55 ng/mL) delivered earlier than those with low AF concentrations of HMGB1 (P = 0.02).

CONCLUSION

(i) Sterile intra-amniotic inflammation is more frequent than microbial-associated intra-amniotic inflammation, and (ii) we propose that danger signals participate in sterile intra-amniotic inflammation in the setting of preterm labor.

Probing the impact of sex steroids and menopause-related sex steroid deprivation on modulation of immune senescence

Immune senescence denotes the general decline in immune system function, characterized by a reduced immune response and an increased inflammatory state. Menopause is a natural change in a women's life, the menopause-related low estrogen levels affecting many body functions, among them the immune system. Numerous human studies with menopausal women and animal models with surgically induced menopause show a clear impact of sex steroids in immune responses. Female superiority in vaccination response and predisposition to infections are eliminated after menopause, while during menopause inflammatory cytokines such as Tumor Necrosis Factor-α (TNF-α), Interleukins-1β, 6, 8 and 13 (IL-1β, IL-6, IL-8, IL-13) and Monocyte Chemoattractant Protein-1 (MCP-1) are increased, implying a molecular connection of sex steroid loss with immune senescence. Moreover, immune cells modify their number and function after the menopausal transition, this offering another explanation for immune senescence. Until now most of the existing studies have concluded that menopause plays an additional role to aging in immune senescence. While it is clear that we are as yet far from thoroughly understanding the molecular pathways connecting sex steroids and menopause with immune senescence, such knowledge is highly likely to enable future targeted interventions in treatment and prevention of age-related diseases in women.

Impact of biomass fuels on pregnancy outcomes in central East India

BACKGROUND

Smoke from biomass burning has been linked to reduced birth weight; association with other birth outcomes is poorly understood. Our objective was to evaluate effects of exposure to biomass smoke on birth weight, preterm birth and stillbirth.

METHODS

Information on household cooking fuel was available for secondary analysis from two cohorts of pregnant women enrolled at delivery in India (n = 1744). Birth weight was measured and the modified Ballard performed to assess gestational age. Linear and logistic regression models were used to explore associations between fuel and birth outcomes. Effect sizes were adjusted in multivariate models for socio-demographic characteristics using propensity score techniques and for medical/obstetric covariates.

RESULTS

Compared to women who use gas (n = 265), women cooking with wood (n = 1306) delivered infants that were on average 112 grams lighter (95% CI -170.1, -54.6) and more likely to be preterm (OR 3.11, 95% CI 2.12, 4.59). Stillbirths were also more common in the wood group (4% versus 0%, p < 0.001). In adjusted models, the association between wood use and birth weight was no longer significant (14 g reduction; 95% CI -93, 66); however, the increased odds for preterm birth persisted (aOR 2.29; 95% CI 1.24, 4.21). Wood fuel use did not increase the risk of delivering either a low birth weight or small for gestational age infant.

CONCLUSIONS

The association between wood fuel use and reduced birth weight was insignificant in multivariate models using propensity score techniques to account for socio-demographic differences. In contrast, we demonstrated a persistent adverse impact of wood fuel use on preterm delivery. If prematurity is confirmed as a consequence of antenatal exposure to household air pollution, perinatal morbidity and mortality from household air pollution may be higher than previously appreciated.

Alterations in TLRs as new molecular markers of congenital infections with Human cytomegalovirus?

Toll-like receptors (TLRs) play a crucial role in non-specific immunity against various infections. The most common intrauterine infection, caused by Human cytomegalovirus (HCMV), results in perinatal morbidity and mortality of primary infected fetuses. The induction of immune response by TLRs was observed in HCMV infections in murine models and cell lines cultured in vitro. Studies reported an immunological response in pregnant women with primary HCMV infection and TLR2 activity in collecting of HCMV particles in placental syncytiotrophoblasts (STs) in vivo and cultured ST, and in stimulation of tumor necrosis factor (TNF)-α expression and damage of villous trophoblast. Expression levels of TLRs are associated with cell type, stage of pregnancy and response to microorganisms. We show the effect of HCMV infection on the development of pregnancy as well as the effect of TLR single-nucleotide polymorphisms on the occurrence and course of infectious diseases, immune response and diseases of pregnancy. We report the impact of TLRs on the function of miRNAs and the altered expression levels of these molecules, as observed in HCMV infections. We suggest that the methylation status of TLR gene promoter regions as epigenetic modifications may be significant in the immune response to HCMV infections. We conclude that it is important to study in detail the molecular mechanisms of TLR function in the immune response to HCMV infections in pregnancy.

Acute lung injury in preterm fetuses and neonates: mechanisms and molecular pathways

Acute lung injury (ALI) results in high morbidity and mortality among preterm neonates and efforts have therefore been devoted to both antenatal and postnatal prevention of the disease. ALI is the result of an inflammatory response which is triggered by a variety of different mechanisms. It mostly affects the fetal lung and, in particular, causes damage to the integrity of the lung's alveolar-capillary unit while weakening its cellular linings. Chemotactic activity and inflammatory products, such as proinflammatory cytokines TNF-α, IL-1, IL-6, IL-11, VEGF,TGF-α and TGF-β, provoke serious damage to the capillary endothelium and the alveolar epithelium, resulting in hyaline membrane formation and leakage of protein-rich edema fluid into the alveoli. Chorioamnionitis plays a major part in triggering fetal lung inflammation, while mechanical ventilation, the application of which is frequently necessary in preterm neonates, also causes ALI by inducing proinflammatory cytokines. Many different ventilation-strategies have been developed in order to reduce potential lung injury. Furthermore, tissue injury may occur as a result of injurious oxygen by-products (Reactive Oxygen Species, ROS), secondary to hyperoxia. Knowledge of the inflammatory pathways that connect intra-amniotic inflammation and ALI can lead to the formulation of novel interventional procedures. Future research should concentrate on the pathophysiology of ALI in preterm neonates and οn possible pharmaceutical interventions targeting prevention and/or resolution of ALI.

Monocyte function in the fetus and the preterm neonate: immaturity combined with functional impairment

It is well known that the innate immunity system, involving the contribution of monocytes and macrophages, may dysfunction in fetuses and preterm neonates. Monocytes are capable of differentiating into dendritic cells (DCs) or into mucosal macrophages during certain infections and of producing inflammatory mediators such as TNF-α (tumor necrosis factor-alpha), nitric oxide, and reactive oxygen species. Fetuses as well as neonates are prone to infections as a result of a defective mechanism within the above mononuclear system. Monocyte function in fetuses and preterm neonates depends on the phagocytic and oxidative capacity of macrophages and their antigen-adhesion ability. Functional rather than anatomical impairment is probably the underlying cause, while a defective production of cytokines, such as TNF-α, IL-6 (Interleukin 6), IL-1β (Interleukin 1 beta), and G-CSF (Granulocyte Colony-Stimulating Factor), has also been involved. The insufficient production of the above inflammatory mediators and the phenomenon of endotoxin intolerance, which latter occurs during entry of any antigen into the premature neonate, place preterm neonates at higher risk for infections. Existing research data are herein presented which, however, are deficient and fragmental, this accounting for the fact that the precise pathophysiology of these disturbances is not yet fully clarified.

Placental growth factor (PlGF): a key to optimizing fetal growth

The needs of the uterus and the fetus for the provision of nutrients and oxygen, supplied by the blood flow, are understandably extremely high, with the circulatory system playing the most important role in this action. Abnormal vascular growth and transformation that create a high vessel resistance network have been associated with various pregnancy pathologies, including miscarriage, small for gestational age (SGA) fetuses with or without preeclampsia and intrauterine growth restriction (IUGR). Placental growth factor (PlGF) has a major role in vasculogenesis and angiogenesis in human placenta. Low concentrations of PlGF and high concentrations of its inhibitor-soluble Fms-like tyrosine kinase-1 (sFlt-1) are linked with impaired angiogenesis and placental development, leading to the above pregnancy complications. The activity of vascular endothelial growth factor (VEGF), which is the most potent of all angiogenic mediators, is partly modulated by PlGF. Although the mechanisms via which PlGF exerts its various effects are still under investigation, we herein discuss the known actions exerted by this major mediator together with its results on fetal growth.

Pregnancy disorders appear to modify the risk for retinopathy of prematurity associated with neonatal hyperoxemia and bacteremia

OBJECTIVE

To explore (1) whether extremely low gestational age newborns exposed to inflammation-associated pregnancy disorders differ in retinopathy of prematurity (ROP) risk from infants exposed to placenta dysfunction-associated disorders, and (2) whether ROP risk associated with postnatal hyperoxemia and bacteremia differs among infants exposed to these disorders.

METHODS

Pregnancy disorders resulting in preterm birth include inflammation-associated: preterm labor, prelabor premature rupture of membranes (pPROM), cervical insufficiency, and abruption and placenta dysfunction-associated: preeclampsia and fetal indication. The risk of severe ROP associated with pregnancy disorders was evaluated by multivariable analyses in strata defined by potential effect modifiers, postnatal hyperoxemia and bacteremia.

RESULTS

Compared to preterm labor, infants delivered after pPROM were at reduced risk of plus disease (Odds ratio = 0.4, 95% confidence interval: 0.2-0.8) and prethreshold/threshold ROP (0.5, 0.3-0.8). Infants delivered after abruption had reduced risk of zone I ROP (0.2, 0.1-0.8) and prethreshold/threshold ROP (0.3, 0.1-0.7). In stratified analyses, infants born after placenta dysfunction had higher risks of severe ROP associated with subsequent postnatal hyperoxemia and bacteremia than infants born after inflammation-associated pregnancy disorders.

CONCLUSION

Infants exposed to placenta dysfunction have an increased risk of severe ROP following postnatal hyperoxemia and bacteremia compared to infants exposed to inflammation-associated pregnancy disorders.

Evolution of gene expression changes in newborn rats after mechanical ventilation with reversible intubation

Mechanical ventilation (MV) is life-saving but potentially harmful for lungs of premature infants. So far, animal models dealt with the acute impact of MV on immature lungs, but less with its delayed effects. We used a newborn rodent model including non-surgical and therefore reversible intubation with moderate ventilation and hypothesized that there might be distinct gene expression patterns after a ventilation-free recovery period compared to acute effects directly after MV. Newborn rat pups were subjected to 8 hr of MV with 60% oxygen (O(2)), 24 hr after injection of lipopolysaccharide (LPS), intended to create a low inflammatory background as often recognized in preterm infants. Animals were separated in controls (CTRL), LPS injection (LPS), or full intervention with LPS and MV with 60% O(2) (LPS + MV + O(2)). Lungs were recovered either directly following (T:0 hr) or 48 hr after MV (T:48 hr). Histologically, signs of ventilator-induced lung injury (VILI) were observed in LPS + MV + O(2) lungs at T:0 hr, while changes appeared similar to those known from patients with chronic lung disease (CLD) with fewer albeit larger gas exchange units, at T:48 hr. At T:0 hr, LPS + MV + O(2) increased gene expression of pro-inflammatory MIP-2. In parallel anti-inflammatory IL-1Ra gene expression was increased in LPS and LPS + MV + O(2) groups. At T:48 hr, pro- and anti-inflammatory genes had returned to their basal expression. MMP-2 gene expression was decreased in LPS and LPS + MV + O(2) groups at T:0 hr, but no longer at T:48 hr. MMP-9 gene expression levels were unchanged directly after MV. However, at T:48 hr, gene and protein expression increased in LPS + MV + O(2) group. In conclusion, this study demonstrates the feasibility of delayed outcome measurements after a ventilation-free period in newborn rats and may help to further understand the time-course of molecular changes following MV. The differences obtained from the two time points could be interpreted as an initial transitory increase of inflammation and a delayed impact of the intervention on structure-related genes.

Protein Microarrays and Midtrimester Amniotic Fluids: A Novel Approach for the Diagnosis of Early Intrauterine Inflammation Related to Preterm Delivery

Novel technologies that allow simultaneous assessment of multiple biomarkers provide new and promising diagnostic/prognostic approaches. By protein microarrays, here we analyzed amniotic fluids (AF) from 50 women with preterm delivery (PTD) and 50 control women, who delivered at term. In detail, cytokines, chemokines, matrix metalloproteinases and antigen-specific antibodies were assessed. The AF analysis showed significant differences between women with preterm and term delivery in the levels of IL-1α, IL-1β, IL-4, IL-6, IL-8, MCP-1, IFN-γ and anti-HSV2 IgG. No significant differences were observed in the levels of TNF-α, MMP-2, MMP-9 and specific IgG for seven vertically transmitted pathogens. In conclusion, we demonstrated the feasibility of protein microarrays in the diagnosis of early intrauterine inflammation. The significant association between the increased levels of certain cytokines and preterm delivery argues on their relevance as early pathogenetic markers for identification of risk patients.

Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix

OBJECTIVE

To assess the diagnostic performance of transabdominal sonographic measurement of cervical length in identifying patients with a short cervix.

METHODS

Cervical length was measured in 220 pregnant women using transabdominal and transvaginal ultrasound (US). Reproducibility and agreement between and within both methods were assessed. The diagnostic accuracy of transabdominal US for identifying cases with a cervical length <25 mm was evaluated.

RESULTS

Twenty-one out of 220 cases (9.5%) had a cervical length <25 mm by transvaginal US. Only 43% (n = 9) of patients with a short cervix were correctly identified by transabdominal US. In patients with a cervical length of <25 mm by transvaginal US, transabdominal measurement of the cervix overestimated this parameter by an average of 8 mm (95% LOAs, -26.4 to 10.5 mm). Among women without a short cervix, transabdominal US underestimated cervical length on average (LOA) by 1.1 mm (95% LOAs, -11.0 to 13.2 mm). Transvaginal US was also more reproducible (intraclass correlation coefficient: (ICC) (0.96; 95% CI, 0.94 to 0.97) based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal US (ICC: 0.71; 95% CI, 0.57 to 0.84). Transvaginal US detected 13 cases with funneling and six cases with sludge whereas only three cases of funneling and one of sludge were detected by transabdominal US.

CONCLUSION

Transabdominal measurement overestimated cervical LOA by 8 mm among women with a short cervix and resulted in the underdiagnosis of 57% of cases.

The frequency and clinical significance of intra-amniotic inflammation in women with preterm uterine contractility but without cervical change: do the diagnostic criteria for preterm labor need to be changed?

OBJECTIVE

The objective of this study was to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm increased uterine contractility with intact membranes but without cervical change.

METHODS

Amniocentesis was performed in 132 patients with regular uterine contractions and intact membranes without cervical change. Amniotic fluid was cultured for bacteria and mycoplasmas and assayed for matrix metalloproteinase-8 (MMP-8). Intra-amniotic inflammation was defined as an elevated amniotic fluid MMP-8 concentration (>23 ng/mL).

RESULTS

(1) Intra-amniotic inflammation was present in 12.1% (16/132); (2) Culture-proven intra-amniotic infection was diagnosed in 3% (4/132) of patients without demonstrable cervical change on admission or during the period of observation; and (3) Patients with intra-amniotic inflammation had significantly higher rates of preterm delivery and adverse outcomes, and shorter amniocentesis-to-delivery intervals than those without intra-amniotic inflammation (P < 0.05 for each). Adverse outcomes included chorioamnionitis, funisitis, and neonatal death.

CONCLUSION

Intra-amniotic inflammation was present in 12% of patients with regular uterine contractions without cervical change, while culture-proven intra-amniotic infection was present in 3%. The presence of intra-amniotic inflammation was a significant risk factor for adverse neonatal outcomes. These observations question whether cervical changes should be required for the diagnosis of preterm labor, because patients without modifications in cervical status on admission or during a period of observation are at risk for adverse pregnancy outcomes.

Vaccination to protect against infection of the female reproductive tract

Infection of the female genital tract can result in serious morbidities and mortalities from reproductive disability, pelvic inflammatory disease and cancer, to impacts on the fetus, such as infant blindness. While therapeutic agents are available, frequent testing and treatment is required to prevent the occurrence of the severe disease sequelae. Hence, sexually transmitted infections remain a major public health burden with ongoing social and economic barriers to prevention and treatment. Unfortunately, while there are two success stories in the development of vaccines to protect against HPV infection of the female reproductive tract, many serious infectious agents impacting on the female reproductive tract still have no vaccines available. Vaccination to prevent infection of the female reproductive tract is an inherently difficult target, with many impacting factors, such as appropriate vaccination strategies/mechanisms to induce a suitable protective response locally in the genital tract, variation in the local immune responses due to the hormonal cycle, selection of vaccine antigen(s) that confers effective protection against multiple variants of a single pathogen (e.g., the different serovars of Chlamydia trachomatis) and timing of the vaccine administration prior to infection exposure. Despite these difficulties, there are numerous ongoing efforts to develop effective vaccines against these infectious agents and it is likely that this important human health field will see further major developments in the next 5 years.

Proteomics/diagnosis of chorioamnionitis and of relationships with the fetal exposome

Proteomics, a relatively young science, originally emerged as a complement to genomics research. By definition, the goal of proteomics is to provide a snapshot of all the proteins within an organism, tissue or biological sample at a given moment. Proteomics has the ability to single out one or more proteins (biomarkers) that change consistently in affected subjects as compared to those disease-free. From a proteomics perspective, chorioamnionitis poses both challenges and opportunities. Challenges relate to the dynamic course of the inflammatory process, and compartmentalization of the gestational sac in relation to the maternal compartment. An inability to evaluate the amniotic fluid non-invasively and repeatedly for meaningful changes in its proteome, and lack of a true gold standard for diagnosis of inflammation and/or infection, represent additional challenges. On the other hand, the unbiased and holistic nature of proteomics offers a real opportunity to improve the current diagnostic and prognostic algorithms for chorioamnionitis. Even at this current stage there are reasons to believe that proteomic biomarkers will improve the understanding of how chorioamnionitis programs or affects the fetus in utero, thus defining its exposome (sum of interactions between genetic make-up of the fetus and the intrauterine environment) of pregnancies affected by infection and/or inflammation. This review summarizes the results of proteomics studies that have aimed or reached these goals.

Immune stress in late pregnant rats decreases length of gestation and fecundity, and alters later cognitive and affective behaviour of surviving pre-adolescent offspring

Immune challenge during pregnancy is associated with preterm birth and poor perinatal development. The mechanisms of these effects are not known. 5α-Pregnan-3α-ol-20-one (3α,5α-THP), the neuroactive metabolite of progesterone, is critical for neurodevelopment and stress responses, and can influence cognition and affective behaviours. To develop an immune challenge model of preterm birth, pregnant Long-Evans rat dams were administered lipopolysaccharide [LPS; 30 μg/kg/ml, intraperitoneal (IP)], interleukin-1β (IL-1β; 1 μg/rat, IP) or vehicle (0.9% saline, IP) daily on gestational days 17-21. Compared to control treatment, prenatal LPS or IL-1β reduced gestational length and the number of viable pups born. At 28-30 days of age, male and female offspring of mothers exposed to prenatal IL-1β had reduced cognitive performance in the object recognition task compared to controls. In females, but not males, prenatal IL-1β reduced anxiety-like behaviour, indicated by entries to the centre of an open field. In the hippocampus, progesterone turnover to its 5α-reduced metabolites was lower in prenatally exposed IL-1β female, but not in male offspring. IL-1β-exposed males and females had reduced oestradiol content in hippocampus, medial prefrontal cortex and diencephalon compared to controls. Thus, immune stress during late pregnancy reduced gestational length and negatively impacted birth outcomes, hippocampal function and central neurosteroid formation in the offspring.

Relationship between periodontal diseases and preterm birth: recent epidemiological and biological data

For ten years, the incidence of preterm birth does not decrease in developed countries despite the promotion of public health programs. Many risk factors have been identified including ethnicity, age, tobacco, and infection. However, almost 50% of preterm birth causes remain unknown. The periodontal diseases are highly prevalent inflammatory and infectious diseases of tooth supporting tissues leading to an oral disability. They influence negatively general health worsening cardiovascular diseases and diabetes. Periodontal diseases have been also suspected to increase the rate of preterm birth, but data remain contradictory. The objective of this review is to present the principal results of epidemiological, biological, and interventional studies on the link between periodontal diseases and preterm birth. The conclusions of this work underline the importance for the physician/obstetrician to identify women at risk for preterm birth and to address these patients to dentist for periodontal examination and treatment in order to limit adverse pregnancy outcomes.

Immune aspects and myometrial actions of progesterone and CRH in labor

Progesterone and corticotropin-releasing hormone (CRH) have a critical role in pregnancy and labor, as changes related to these hormones are crucial for the transition from myometrial quiescence to contractility. The mechanisms related to their effect differ between humans and other species, thus, despite extensive research, many questions remain to be answered regarding their mediation in human labor. Immune responses to progesterone and CRH are important for labor. Progesterone acts as an immunomodulator which controls many immune actions during pregnancy, and its withdrawal releases the inhibitory action on inflammatory pathways. In humans, a "functional" progesterone withdrawal occurs with onset of labor through changes in progesterone metabolism, progesterone receptors, and other molecules that either facilitate or antagonize progesterone function. Placental CRH acts on the fetal pituitary-adrenal axis to stimulate adrenal production of androgens and cortisol and also acts directly on myometrial cells via its receptors. CRH also affects inflammatory signals and vice versa. Interactions between progesterone and CRH additionally occur during labor. We describe the role of these two hormones in human myometrium and their interactions with the immune system during labor.

Association between maternal comorbidity and preterm birth by severity and clinical subtype: retrospective cohort study

Background

Preterm birth (PTB) is a major cause of infant morbidity and mortality, but the relationship between comorbidity and PTB by clinical subtype and severity of gestational age remains poorly understood. We evaluated associations between maternal comorbidities and PTB by clinical subtype and gestational age.

Methods

We conducted a retrospective cohort study of 1,329,737 singleton births delivered in hospitals in the province of Québec, Canada, 1989-2006. PTB was classified by clinical subtype (medically indicated, preterm premature rupture of membranes (PPROM), spontaneous preterm labour) and gestational age (< 28, 28-31, 32-36 completed weeks). Odds ratios (OR) of PTB by clinical subtype for systemic and localized maternal comorbidities were estimated using polytomous logistic regression, adjusting for maternal age, grand multiparity, and period. Attributable fractions were calculated.

Results

PTB rates were higher among mothers with comorbidity (10.9%) compared to those without comorbidity (4.7%). Several comorbidities were associated with greater odds of medically indicated PTB compared with no comorbidity, but only comorbidities localized to the reproductive system were associated with spontaneous PTB. Drug dependence and mental disorders were strongly associated with PPROM and spontaneous PTBs across all gestational ages (OR > 2.0). At the population level, several major comorbidities (placental abruption, chorioamnionitis, oliogohydramnios, structural abnormality, cervical incompetence) were key contributors to all clinical subtypes of PTB, especially at < 32 weeks. Major systemic comorbidities (preeclampsia, anemia) were key contributors to PPROM and medically indicated PTBs.

Conclusions

The relationship between comorbidity and clinical subtypes of PTB depends on gestational age. Prevention of PPROM and spontaneous PTB may benefit from greater attention to preeclampsia, anemia and comorbidities localized to the reproductive system.

Risk of spontaneous preterm delivery in a low-risk population: the impact of maternal febrile episodes, urinary tract infection, pneumonia and ear-nose-throat infections

OBJECTIVE

To assess the associations between maternal infections during pregnancy (i.e. ear-nose-throat infection, pneumonia, urinary tract infection, febrile episodes and influenza-like infection) and spontaneous preterm delivery (SPTD).

STUDY DESIGN

Prospective questionnaire data from the Norwegian Mother and Child Cohort (MoBa) study, including more than 100000 pregnancies and, collected during 1999-2008, were used. Linked data from the Medical Birth Registry of Norway were added. SPTD occurring between gestational weeks 22+0 days and 36+6 days was the main outcome. Data were analysed in two steps because questionnaires (including information about occurrence of the various infections so far) were completed at different stages of pregnancy. Hazard ratios (HR) were obtained using Cox regression.

RESULTS

The SPTD proportion was low in this cohort: 2.9% and 2.7% at the two analysis steps, respectively. After exclusions, 67310 and 60689 pregnancies, respectively, remained for the analyses. Ear-nose-throat infections occurring before week 17 were associated with an increased risk of SPTD in the first (HR: 1.27, 95% CI: 1.08-1.50) and second (HR: 1.26, 95% CI: 1.04-1.52) step of the analysis, but not if occurring later in pregnancy. None of the other maternal infections were associated with an increased risk of SPTD.

CONCLUSION

In this low-risk population, ear-nose-throat infection in early pregnancy was associated with an increased risk of SPTD. However, infectious morbidity in later pregnancy was not. Thus, the link between maternal infection and preterm delivery may vary in different populations and health care settings.

Myth: tocolysis for prevention of preterm birth has a major role in modern obstetrics

Tocolytics are widely used to reduce uterine activity in the context of preterm labour. Growing evidence that bacterial colonization of fetal membranes and amniotic fluid triggers an inflammatory response in mother and fetus and leads to preterm labour and long term neurological and respiratory complications in the neonate also raises questions about the desirability of prolonging pregnancy in this context. Combined with recent meta-analyses that fail to demonstrate improvements in neonatal outcome with tocolytic use, and a poor maternal/fetal side-effect profile, the case for continued use of these drugs needs to be questioned.

The role of inflammation and infection in preterm birth

Much emphasis in recent decades has been devoted to inflammation and infection as a premier causal mechanism of preterm birth. This article explores the epidemiologic, clinical, and animal data that exist to support this conceptual paradigm as well as proposed mechanisms through which to potentially mitigate the adversity of prematurity. Truly successful interventions are not likely to occur until the pathogenesis of preterm birth and the role of inflammation in causing not only parturition but also fetal and neonatal injury is fully elucidated.

Birth weight of infants of mothers with aggressive periodontitis

BACKGROUND

It was hypothesized that if periodontal infections predispose low birth weights and premature birth, then such outcomes should be apparent when the mother has aggressive periodontitis (AgP).

METHODS

Birth weight data were collected by questionnaire from females with AgP, their periodontally healthy siblings, and unrelated periodontally healthy women. Both prospective and retrospective birth outcome data were used. Because many of the periodontal evaluations were performed after the births, there were incomplete data regarding most of the risk factors for low birth weight. We determined associations between mothers' periodontal diagnoses and clinical variables and the reported birth weights.

RESULTS

There were no significant differences in mean birth weights of babies born to control subjects or AgP patients. This was true whether all the births were considered or only those reported <1 or 2 years before periodontal examination. For periodontally healthy controls, 13.2% of babies born to siblings of AgP patients and 12.8% of babies born to unrelated mothers weighed <2,500 g, whereas 9.9% of those born to mothers with generalized AgP and 10.3% of those born to mothers with localized AgP weighed <2,500 g.

CONCLUSIONS

Because of the relative rarity of AgP in the population, and attendant difficulties in performing a prospective study of its association with pregnancy outcomes, we used a compromised approach using prospective data as well as weaker retrospective data assuming that disease onset was likely before the births. Our results, within the limitations of this approach, indicate no evidence that AgP in the mother predisposes low birth weights. AgP has many unique biologic characteristics that differentiate it from chronic forms of periodontal disease, and the possible lack of its association with birth weight may be another such characteristic.

HISTOLOGICAL CHORIOAMNIONITIS: CURRENT CONCEPTS OF DIAGNOSIS, CLASSIFICATION AND CLINICAL SIGNIFICANCE

Interest in the clinical associations between maternal intrapartum fever and adverse neonatal outcome has been longstanding, with publications of a relationship between maternal fever and cerebral palsy dating from the 1950s. Further recognition of the associations between either clinically or histologically characterised chorioamnionitis, ascending infection and neonatal wellbeing followed, with numerous reports in the 1960s and 70s, particularly as the neonatal significance of group B streptococcal infections became apparent. Similarly, with the systematic introduction of diagnostic light microscopy into clinical medicine, chorioamnionitis (inflammation of the placental membranes) and funisitis (inflammation of the umbilical cord) were recognised as distinct histological entities, with increasing recognition that the aetiology was likely to be infective. There are numerous texts discussing in detail the pathogenesis and histological features of chorioamnionitis and funisitis. The aim of this review is to provide an overview of the salient associated issues for clinical practitioners and to highlight areas of ongoing uncertainty and recent developments in understanding.

Effects of air pollution on neonatal prematurity in Guangzhou of China: a time-series study

BACKGROUND

Over the last decade, a few studies have investigated the possible adverse effects of ambient air pollution on preterm birth. However, the correlation between them still remains unclear, due to insufficient evidences.

METHODS

The correlation between air pollution and preterm birth in Guangzhou city was examined by using the Generalized Additive Model (GAM) extended Poisson regression model in which we controlled the confounding factors such as meteorological factors, time trends, weather and day of the week (DOW). We also adjusted the co linearity of air pollutants by using Principal Component Analysis. The meteorological data and air pollution data were obtained from the Meteorological Bureau and the Environmental Monitoring Centre, while the medical records of newborns were collected from the perinatal health database of all obstetric institutions in Guangzhou, China in 2007.

RESULTS

In 2007, the average daily concentrations of NO₂, PM₁₀ and SO₂ in Guangzhou, were 61.04, 82.51 and 51.67 μg/m³ respectively, where each day an average of 21.47 preterm babies were delivered. Pearson correlation analysis suggested a negative correlation between the concentrations of NO₂, PM₁₀, SO₂, and temperature as well as relative humidity. As for the time-series GAM analysis, the results of single air pollutant model suggested that the cumulative effects of NO₂, PM₁₀ and SO₂ reached its peak on day 3, day 4 and day 3 respectively. An increase of 100 μg/m³ of air pollutants corresponded to relative risks (RRs) of 1.0542 (95%CI: 1.0080 ~1.1003), 1.0688 (95%CI: 1.0074 ~1.1301) and 1.1298 (95%CI: 1.0480 ~1.2116) respectively. After adjusting co linearity by using the Principal Component Analysis, the GAM model of the three air pollutants suggested that an increase of 100 μg/m³ of air pollutants corresponded to RRs of 1.0185 (95%CI: 1.0056~1.0313), 1.0215 (95%CI: 1.0066 ~1.0365) and 1.0326 (95%CI: 1.0101 ~1.0552) on day 0; and RRs of the three air pollutants, at their strongest cumulative effects, were 1.0219 (95%CI: 1.0053~1.0386), 1.0274 (95%CI: 1.0066~1.0482) and 1.0388 (95%CI: 1.0096 ~1.0681) respectively.

CONCLUSIONS

This study indicates that the daily concentrations of air pollutants such as NO₂, PM₁₀ and SO₂ have a positive correlation with the preterm births in Guangzhou, China.

The oxytocin-oxytocin receptor system and its antagonists as tocolytic agents

Oxytocin, a hormone involved in numerous physiologic processes, plays a central role in the mechanisms of parturition and lactation. It acts through its receptor, which belongs to the G-protein-coupled receptor superfamily, while Gq/phospholipase C (PLC)/inositol 1,4,5-triphosphate (InsP3) is the main pathway via which it exerts its action in the myometrium. Changes in receptor levels, receptor desensitization, and locally produced oxytocin are factors that influence the effect of oxytocin on uterine contractility in labor. Activation of oxytocin receptor causes myometrial contractions by increasing intracellular Ca(+2) and production of prostaglandins. Since oxytocin induces contractions, the inhibition of its action has been a target in the management of preterm labor. Atosiban is today the only oxytocin receptor antagonist that is available as a tocolytic. However, the quest for oxytocin receptor antagonists with a better pharmacological profile has led to the synthesis of peptide and nonpeptide molecules such as barusiban, retosiban, L-368,899, and SSR-126768A. Many of these oxytocin receptor antagonists are used only as pharmacological tools, while others have tocolytic action. In this paper, we summarize the action of oxytocin and its receptor and we present an overview of the clinical and experimental data of oxytocin antagonists and their tocolytic action.