Antenatal steroids and neonatal outcome after chorioamnionitis: a meta-analysis

The prevention, diagnosis and treatment of premature labor

BACKGROUND

The percentage of preterm births in Germany is high at 9%, but stable. 77% of cases of perinatal death are in prematurely born infants. Intensive research efforts are being directed toward the development of new means of primary and secondary prevention, diagnostic assessment, and pharmacotherapy of premature labor.

METHODS

We review pertinent publications that were retrieved by a selective search of the literature from 1966 to 2012, including current meta-analyses from the Cochrane database and the guidelines of German and foreign obstetric societies.

RESULTS

Preterm labor is a multifactorial problem. The current treatment options are symptomatic, rather than causally directed. Preventive treatment with progesterone can lower the rate of preterm birth in high-risk groups by more than 30%. Transporting the pregnant women to an appropriately qualified perinatal care center and induction of fetal lung maturation lowers perinatal mortality. A variety of tocolytic drugs with different mechanisms of action (betamimetics, oxytocin antagonists, calcium-channel blockers, NO donors, and inhibitors of prostaglandin synthesis) can be used for individualized tocolytic treatment. Premature rupture of the membranes is an indication for antibiotics.

CONCLUSION

The goal of all attempts to prevent and treat preterm labor is to improve preterm infants' chances of surviving with as few complications as possible. The methods discussed here can be used to prolong pregnancies at risk for preterm labor and so to reduce perinatal morbidity and mortality.

Chorioamnionitis and prematurity: a critical review

Chorioamnionitis is the inflammatory response to an acute inflammation of the membranes and chorion of the placenta. We provide a critical review of the relationship between chorioamnionitis and the risk of prematurity and adverse maternal-fetal outcome. Chorioamnionitis results as a major risk factor for preterm birth and its incidence is strictly related to gestational age. It is associated with a significant maternal, perinatal and long-term adverse outcomes. The principal neonatal complications are neonatal sepsis, pneumonia, bronchopulmonary dysplasia, perinatal death, cerebral palsy and intraventricular hemorrhage. The role in neonatal outcome is still controversial and more conclusive studies could clarify the relationship between chorioamnionitis and adverse neonatal outcome. Maternal complications include abnormal progression of labour, caesarean section, postpartum hemorrhage, abnormal response after use of oxytocin and placenta abruption. Prompt administration of antibiotics and steroids could improve neonatal outcomes.

Antenatal glucocorticoids counteract LPS changes in TGF-β pathway and caveolin-1 in ovine fetal lung

Inflammation and antenatal glucocorticoids, the latter given to mothers at risk for preterm birth, affect lung development and may contribute to the development of bronchopulmonary dysplasia (BPD). The effects of the combined exposures on inflammation and antenatal glucocorticoids on transforming growth factor (TGF)-β signaling are unknown. TGF-β and its downstream mediators are implicated in the etiology of BPD. Therefore, we asked whether glucocorticoids altered intra-amniotic lipopolysaccharide (LPS) effects on TGF-β expression, its signaling molecule phosphorylated sma and mothers against decapentaplegic homolog 2 (pSmad2), and the downstream mediators connective tissue growth factor (CTGF) and caveolin-1 (Cav-1). Ovine singleton fetuses were randomized to receive either an intra-amniotic injection of LPS and/or maternal betamethasone (BTM) intramuscularly 7 and/or 14 days before delivery at 120 days gestational age (GA; term = 150 days GA). Saline was used for controls. Protein levels of TGF-β1 and -β2 were measured by ELISA. Smad2 phosphorylation was assessed by immunohistochemistry and Western blot. CTGF and Cav-1 mRNA and protein levels were determined by RT-PCR and Western blot. Free TGF-β1 and -β2 and total TGF-β1 levels were unchanged after LPS and/or BTM exposure, although total TGF-β2 increased in animals exposed to BTM 7 days before LPS. pSmad2 immunostaining increased 7 days after LPS exposure although pSmad2 protein expression did not increase. Similarly, CTGF mRNA and protein levels increased 7 days after LPS exposure as Cav-1 mRNA and protein levels decreased. BTM exposure before LPS prevented CTGF induction and Cav-1 downregulation. This study demonstrated that the intrauterine inflammation-induced TGF-β signaling can be inhibited by antenatal glucocorticoids in fetal lungs.

Proactive management of extreme prematurity: disagreement between obstetricians and neonatologists

OBJECTIVE

To verify, in extremely preterm infants, if disagreement between obstetricians and neonatologists regarding proactive management is associated with early death.

STUDY DESIGN

Prospective cohort of 484 infants with 23(0/7) to 26(6/7) weeks, without malformations, born from January 2006 to December 2009 in eight Brazilian hospitals. Pro-active management was defined as indication of ≥1 dose of antenatal steroid or cesarean section (obstetrician) and resuscitation at birth according to the international guidelines (neonatologist). Main outcome was neonatal death in the first 24  h of life.

RESULT

Obstetricians and neonatologists disagreed in 115 (24%) patients: only neonatologists were proactive in 107 of them. Disagreement between professionals increased 2.39 times the chance of death in the first day (95% confidence interval 1.40 to 4.09), adjusted for center and maternal/neonatal clinical conditions.

CONCLUSION

In infants with 23 to 26 weeks of gestation, disagreement between obstetricians and neonatologists, translated as lack of antenatal steroids and/or vaginal delivery, despite resuscitation procedures, increases the odds of death in the first day.

LPS-induced chorioamnionitis and antenatal corticosteroids modulate Shh signaling in the ovine fetal lung

Chorioamnionitis and antenatal corticosteroids mature the fetal lung functionally but disrupt late-gestation lung development. Because Sonic Hedgehog (Shh) signaling is a major pathway directing lung development, we hypothesized that chorioamnionitis and antenatal corticosteroids modulated Shh signaling, resulting in an altered fetal lung structure. Time-mated ewes with singleton ovine fetuses received an intra-amniotic injection of lipopolysaccharide (LPS) and/or maternal intramuscular betamethasone 7 and/or 14 days before delivery at 120 days gestational age (GA) (term = 150 days GA). Intra-amniotic LPS exposure decreased Shh mRNA levels and Gli1 protein expression, which was counteracted by both betamethasone pre- or posttreatment. mRNA and protein levels of fibroblast growth factor 10 and bone morphogenetic protein 4, which are important mediators of lung development, increased 2-fold and 3.5-fold, respectively, 14 days after LPS exposure. Both 7-day and 14-day exposure to LPS changed the mRNA levels of elastin (ELN) and collagen type I alpha 1 (Col1A1) and 2 (Col1A2), which resulted in fewer elastin foci and increased collagen type I deposition in the alveolar septa. Corticosteroid posttreatment prevented the decrease in ELN mRNA and increased elastin foci and decreased collagen type I deposition in the fetal lung. In conclusion, fetal lung exposure to LPS was accompanied by changes in key modulators of lung development resulting in abnormal lung structure. Betamethasone treatment partially prevented the changes in developmental processes and lung structure. This study provides new insights into clinically relevant prenatal exposures and fetal lung development.

Effects of chorioamnionitis on the fetal lung

Very preterm infants are commonly exposed to a chronic, often asymptomatic, chorioamnionitis that is diagnosed by histologic evaluation of the placenta only after delivery. The reported effects of these exposures on fetal lungs are inconsistent because exposure to different organisms, durations of exposure, and fetal/maternal responses affect outcomes. In experimental models, chorioamnionitis can both injure and mature the fetal lung and cause immune nodulation. Postnatal care strategies also change how chorioamnionitis relates to clinical outcomes such as bronchopulmonary dysplasia.

Ovine fetal thymus response to lipopolysaccharide-induced chorioamnionitis and antenatal corticosteroids

Rationale

Chorioamnionitis is associated with preterm delivery and involution of the fetal thymus. Women at risk of preterm delivery receive antenatal corticosteroids which accelerate fetal lung maturation and improve neonatal outcome. However, the effects of antenatal corticosteroids on the fetal thymus in the settings of chorioamnionitis are largely unknown. We hypothesized that intra-amniotic exposure to lipopolysaccharide (LPS) causes involution of the fetal thymus resulting in persistent effects on thymic structure and cell populations. We also hypothesized that antenatal corticosteroids may modulate the effects of LPS on thymic development.

Methods

Time-mated ewes with singleton fetuses received an intra-amniotic injection of LPS 7 or 14 days before preterm delivery at 120 days gestational age (term = 150 days). LPS and corticosteroid treatment groups received intra-amniotic LPS either preceding or following maternal intra-muscular betamethasone. Gestation matched controls received intra-amniotic and maternal intra-muscular saline. The fetal intra-thoracic thymus was evaluated.

Results

Intra-amniotic LPS decreased the cortico-medullary (C/M) ratio of the thymus and increased Toll-like receptor (TLR) 4 mRNA and CD3 expression indicating involution and activation of the fetal thymus. Increased TLR4 and CD3 expression persisted for 14 days but Foxp3 expression decreased suggesting a change in regulatory T-cells. Sonic hedgehog and bone morphogenetic protein 4 mRNA, which are negative regulators of T-cell development, decreased in response to intra-amniotic LPS. Betamethasone treatment before LPS exposure attenuated some of the LPS-induced thymic responses but increased cleaved caspase-3 expression and decreased the C/M ratio. Betamethasone treatment after LPS exposure did not prevent the LPS-induced thymic changes.

Conclusion

Intra-amniotic exposure to LPS activated the fetal thymus which was accompanied by structural changes. Treatment with antenatal corticosteroids before LPS partially attenuated the LPS-induced effects but increased apoptosis in the fetal thymus. Corticosteroid administration after the inflammatory stimulus did not inhibit the LPS effects on the fetal thymus.

Neonatal posthemorrhagic hydrocephalus from prematurity: pathophysiology and current treatment concepts

OBJECT

Preterm infants are at risk for perinatal complications, including germinal matrix-intraventricular hemorrhage (IVH) and subsequent posthemorrhagic hydrocephalus (PHH). This review summarizes the current understanding of the epidemiology, pathophysiology, management, and outcomes of IVH and PHH in preterm infants.

METHODS

The MEDLINE database was systematically searched using terms related to IVH, PHH, and relevant neurosurgical procedures to identify publications in the English medical literature. To complement information from the systematic search, pertinent articles were selected from the references of articles identified in the initial search.

RESULTS

This review summarizes the current knowledge regarding the epidemiology and pathophysiology of IVH and PHH, primarily using evidence-based studies. Advances in obstetrics and neonatology over the past few decades have contributed to a marked improvement in the survival of preterm infants, and neurological morbidity is also starting to decrease. The incidence of IVH is declining, and the incidence of PHH will likely follow. Currently, approximately 15% of preterm infants who suffer severe IVH will require permanent CSF diversion. The clinical presentation and surgical management of symptomatic PHH with temporary ventricular reservoirs (ventricular access devices) and ventriculosubgaleal shunts and permanent ventriculoperitoneal shunts are discussed. Preterm infants who develop PHH that requires surgical treatment remain at high risk for other related neurological problems, including cerebral palsy, epilepsy, and cognitive and behavioral delay. This review highlights numerous opportunities for further study to improve the care of these children.

CONCLUSIONS

A better grasp of the pathophysiology of IVH is beginning to impact the incidence of IVH and PHH. Neonatologists conduct rigorous Class I and II studies to advance the outcomes of preterm infants. The need for well-designed multicenter trials is essential because of the declining incidence of IVH and PHH, variations in referral patterns, and neonatal ICU and neurosurgical management. Well-designed multicenter trials will eventually produce evidence to enable neurosurgeons to provide their smallest, most vulnerable patients with the best practices to minimize perioperative complications and permanent shunt dependence, and most importantly, optimize long-term neurodevelopmental outcomes.

Evidence for the clinical management of chorioamnionitis

Acute chorioamnionitis or intra-amniotic infection is defined by maternal fever in association with at least one additional clinical criterion including maternal or fetal tachycardia, maternal leukocytosis, uterine tenderness, or foul amniotic fluid odor. In clinically uncertain cases, the diagnosis can be augmented by routine laboratory studies (e.g. white blood cell count and differential count and acute phase reactants) and assays done on amniotic fluid. In general, the clinical management of chorioamnionitis is based on observational or cohort studies; only a few randomized controlled trials have been done. Prompt administration of antibiotics and delivery decrease maternal and neonatal morbidity. The most commonly used antibiotic regimen is ampicillin and gentamicin. Recent evidence supports daily rather than three-times-daily dosing of gentamicin for greater efficacy and decreased fetal toxicity. There is no evidence demonstrating harm with the administration of corticosteroids (to promote fetal lung maturity) in women with acute chorioamnionitis. Cesarean delivery should be reserved for standard obstetric indications.

The association of histological chorioamnionitis and antenatal steroids on neonatal outcome in preterm infants born at less than thirty-four weeks' gestation

BACKGROUND

Despite continuous research on the prevention of preterm labor, preterm delivery still occurs often. Different neonatal outcomes in association with chorioamnionitis might occur with the introduction of antenatal steroids.

OBJECTIVE

The purpose of this study was to determine the effect of chorioamnionitis on the outcome of preterm infants and the association of antenatal steroids in the presence of histological chorioamnionitis (HC).

METHODS

Two hundred and fifty-seven infants born at <34 weeks and admitted to Ewha Womans University Hospital from 2005 to 2010 were enrolled. They were divided into 2 groups, one with HC (n = 89) and the other without HC (n = 168). The clinical characteristics and outcomes of the preterm infants including sepsis, respiratory distress syndrome, intraventricular hemorrhage (IVH) and bronchopulmonary dysplasia (BPD) were analyzed.

RESULTS

HC was associated with IVH (p = 0.019) and early-onset sepsis (p = 0.038). In the HC group, the infants exposed to antenatal steroids developed BPD less than those without steroid exposure. The duration of mechanical ventilation was significantly decreased in the group with antenatal steroids.

CONCLUSION

HC increased the incidence of early-onset sepsis and IVH in preterm infants of less than 34 weeks' gestation with a high odds ratio of 9.54. In the presence of HC, antenatal steroids significantly decreased the incidence of BPD.

Intra-amniotic LPS and antenatal betamethasone: inflammation and maturation in preterm lamb lungs

The proinflammatory stimulus of chorioamnionitis is commonly associated with preterm delivery. Women at risk of preterm delivery receive antenatal glucocorticoids to functionally mature the fetal lung. However, the effects of the combined exposures of chorioamnionitis and antenatal glucocorticoids on the fetus are poorly understood. Time-mated ewes with singleton fetuses received an intra-amniotic injection of lipopolysaccharide (LPS) either preceding or following maternal intramuscular betamethasone 7 or 14 days before delivery, and the fetuses were delivered at 120 days gestational age (GA) (term = 150 days GA). Gestation matched controls received intra-amniotic and maternal intramuscular saline. Compared with saline controls, intra-amniotic LPS increased inflammatory cells in the bronchoalveolar lavage and myeloperoxidase, Toll-like receptor 2 and 4 mRNA, PU.1, CD3, and Foxp3-positive cells in the fetal lung. LPS-induced lung maturation measured as increased airway surfactant and improved lung gas volumes. Intra-amniotic LPS-induced inflammation persisted until 14 days after exposure. Betamethasone treatment alone induced modest lung maturation but, when administered before intra-amniotic LPS, suppressed lung inflammation. Interestingly, betamethasone treatment after LPS did not counteract inflammation but enhanced lung maturation. We conclude that the order of exposures of intra-amniotic LPS or maternal betamethasone had large effects on fetal lung inflammation and maturation.

Chorioamnionitis - new ideas from experimental models

Antenatal inflammation may be associated with adverse neonatal outcomes in several organ systems. Bacteria and a few viruses have been detected in cases of microbial invasion of the amniotic cavity which is referred to as chorioamnionitis. Many aspects of this disease remain unclear such as the causes, time of onset and the fetal responses. Chorioamnionitis was therefore induced in pregnant sheep by injections of lipopolysaccharide (LPS) or Ureaplasma species into the amniotic cavity under ultrasound guidance. LPS-induced chorioamnionitis caused a cascade of organ injury, inflammation, and remodeling. The organ-specific changes were accompanied by systemic effects. The systemic effects after LPS-induced chorioamnionitis resulted in immune suppression against several Toll-like receptor agonists (cross-tolerance). Ureaplasma induced chorioamnionitis made changes in the fetal lung structure depending on the time of infection during pregnancy. The mechanisms of inflammation, structural damage and decreased expression of growth factors need to be further studied to determine therapeutic targets in suitable animal models.