Fetal membrane histology in preterm premature rupture of membranes: comparison to controls, and between antibiotic and placebo treatment. The National Institute of Child Health and Human Development Maternal Fetal Medicine Units Network, Bethesda, MD, USA

Hemodynamic assessment in patients with preterm premature rupture of the membranes (pPROM)

OBJECTIVE

The aim of this study was to assess the hemodynamic differences in women with pPROM versus physiological pregnancies.

STUDY DESIGN

This was a prospective case control study of 15 patients with pPROM and 45 controls. Patients and controls were submitted at enrollment to a non-invasive hemodynamic evaluation with UltraSonic Cardiac Output Monitor (USCOM), and to blood tests to check white blood cells count and C-reactive protein (CRP) levels. We followed pPROM patients until delivery noting fetal/neonatal and maternal unfavorable outcomes (maternal fever, APGAR 1' and 5'< 7, stillbirth).

RESULTS

Patients with pPROM showed higher values of cardiac output (9.1 ± 2.3 vs 7.1 ± 0.85, p < 0.01), lower systemic vascular resistances (792.1 ± 162 vs 1006.2 ± 110.7, p < 0.01), higher minute distance (32.3 ± 7.8 vs 25 ± 2.8, p < 0.01), lower Potential to Kinetic Energy Ratio (16.5 ± 5.3 vs 22.4 ± 6.8, p < 0.01), higher heart rate (97.5 ± 15.4 vs 82.4 ± 12, p < 0.01) and higher oxygen delivery (1313.2 ± 325.8 vs 1080.7 ± 151.8, p < 0.01) vs. controls. Six out of 15 pPROM patients had an unfavorable outcome. There were no significant differences in CRP levels and WBC count at admission in the two pPROM subgroups, whereas maternal hemodynamics was characterized by lower SVR (718 ± 72 vs 863 ± 123, p = 0.02) in subsequently complicated patients.

CONCLUSIONS

Maternal hemodynamics is altered in pPROM patients, with a lower Systemic Vascular Resistance and higher Cardiac Output vs. controls. This hyperdynamic circulation appears to anticipates the changes of serum markers of inflammation (CRP, WBC count) and seems to be more pronounced at admission in pPROM patients developing unfavorable outcomes.

Does low dose aspirin prescribed for risk of early onset preeclampsia reduce the prevalence of preterm prelabor rupture of membranes?

Background: Placental dysfunction, inflammation and degradation of fetal membranes has been hypothesized as a cause of preterm prelabor of rupture of membranes.Objective: To examine the effect of aspirin, an anti-inflammatory agent, on the prevalence of preterm prelabor rupture of membranes (PPRoMs).Methods: A retrospective analysis was conducted to examine the effect of aspirin on the prevalence of PPRoM. Aspirin (150 mg, nocte) was prescribed to women who were identified through a screening program at 11-13⁺⁶ weeks' gestation as being at high risk for developing early-onset preeclampsia. Women who were at low risk for developing preeclampsia did not receive aspirin. The prevalence of PPRoM was compared with an observational cohort.Results: In the observational cohort, there were 3027 women, including 32 (1.1%) cases of PPRoM. The prevalence of PPRoM in the high risk group was 3.1% (4/128) and was statistically significantly higher compared to the low risk group (1.0%) (28/2899). The relative risk was 3.02 (95% CI 1.2-7.7; p= .04). In the interventional cohort, there were 7280 women, with 114 (1.6%) cases of PPRoM. The prevalence of PPRoM in the high risk group who were treated with aspirin was 1.8% (14/766) compared to 1.5% (100/6516) in the low risk group (p= .54). The prevalence of PPRoM in high risk patients in the observational group (who did not receive aspirin) compared with the high risk patients in the interventional group (who were treated with aspirin) was not statistically significant (p= .31).Conclusions: PPRoM is significantly associated with a description of high risk for ePET; although, this algorithm is not a good screening tool for predicting PPRoM. Aspirin treatment of women deemed high risk for ePET is safe in the context of PPRoM and there may be some reduction in prevalence of PPRoM in treated high risk women; although, this study was not powered to demonstrate a small reduction in the prevalence of PPRoM. The findings merit further investigation through a larger prospective study with adequate sample size.

All-trans retinoic acid promotes wound healing of primary amniocytes through the induction of LOXL4, a member of the lysyl oxidase family

Thirty percent of preterm births directly result from preterm premature rupture of fetal membranes (PPROM). Clinical management currently proposes using a collagen plug to mechanically stop loss of amniotic fluid. Vitamin A and its active metabolite (retinoic acid) have well-known pro-healing properties and could thus make good candidates as a proposable adjuvant to this mechanical approach. Here we investigate the molecular mechanisms involved in the pro-healing properties of all-trans retinoic acid (atRA) in fetal membranes via an approach using an in vitro primary amniocyte wound model and transcriptomics. The results demonstrate that atRA promotes migration in primary amniocytes, improving wound healing in vitro by up to 90%. This effect is mediated by the induction of LOXL4, which plays a crucial role in the dynamics of the extracellular matrix by regulating collagen reticulation. This new insight into how atRA exerts its pro-healing properties prompts us to propose using atRA as a candidate strategy to help prevent future PPROM.

A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM

OBJECTIVES

To determine whether a new antibiotic regimen could reduce the frequency of intra-amniotic inflammation/infection in patients with preterm PROM.

STUDY DESIGN

This retrospective cohort study was conducted to evaluate the effect of antibiotics on the frequency of intra-amniotic inflammation/infection based on the results of follow-up transabdominal amniocenteses from 89 patients diagnosed with preterm PROM who underwent serial amniocenteses. From 1993-2003, ampicillin and/or cephalosporins or a combination was used ("regimen 1"). A new regimen (ceftriaxone, clarithromycin and metronidazole) was used from 2003-2012 ("regimen 2"). Amniotic fluid was cultured and matrix metalloproteinase-8 (MMP-8) concentrations were measured.

RESULTS

(1) The rates of intra-amniotic inflammation and intra-amniotic inflammation/infection in patients who received regimen 2 decreased during treatment from 68.8% to 52.1% and from 75% to 54.2%, respectively. In contrast, in patients who received regimen 1, the frequency of intra-amniotic inflammation and infection/inflammation increased during treatment (31.7% to 55% and 34.1% to 58.5%, respectively); and (2) intra-amniotic inflammation/infection was eradicated in 33.3% of patients who received regimen 2, but in none who received regimen 1.

CONCLUSION

The administration of ceftriaxone, clarithromycin and metronidazole was associated with a more successful eradication of intra-amniotic inflammation/infection and prevented secondary intra-amniotic inflammation/infection more frequently than an antibiotic regimen which included ampicillin and/or cephalosporins in patients with preterm PROM.

A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM

OBJECTIVE

Antibiotic administration is a standard practice in preterm premature rupture of membranes (PROM). Specific anti-microbial agents often include ampicillin and/or erythromycin. Anaerobes and genital mycoplasmas are frequently involved in preterm PROM, but are not adequately covered by antibiotics routinely used in clinical practice. Our objective was to compare outcomes of PROM treated with standard antibiotic administration versus a new combination more effective against these bacteria.

STUDY DESIGN

A retrospective study compared perinatal outcomes in 314 patients with PROM <34 weeks receiving anti-microbial regimen 1 (ampicillin and/or cephalosporins; n = 195, 1993-2003) versus regimen 2 (ceftriaxone, clarithromycin and metronidazole; n = 119, 2003-2012). Intra-amniotic infection/inflammation was assessed by positive amniotic fluid culture and/or an elevated amniotic fluid MMP-8 concentration (>23 ng/mL).

RESULTS

(1) Patients treated with regimen 2 had a longer median antibiotic-to-delivery interval than those with regimen 1 [median (interquartile range) 23 d (10-51 d) versus 12 d (5-52 d), p < 0.01]; (2) patients who received regimen 2 had lower rates of acute histologic chorioamnionitis (50.5% versus 66.7%, p < 0.05) and funisitis (13.9% versus 42.9%, p < 0.001) than those who had received regimen 1; (3) the rates of intra-ventricular hemorrhage (IVH) and cerebral palsy (CP) were significantly lower in patients allocated to regimen 2 than regimen 1 (IVH: 2.1% versus 19.0%, p < 0.001 and CP: 0% versus 5.7%, p < 0.05); and (4) subgroup analysis showed that regimen 2 improved perinatal outcomes in pregnancies with intra-amniotic infection/inflammation, but not in those without intra-amniotic infection/inflammation (after adjusting for gestational age and antenatal corticosteroid administration).

CONCLUSION

A new antibiotic combination consisting of ceftriaxone, clarithromycin, and metronidazole prolonged the latency period, reduced acute histologic chorioamnionitis/funisitis, and improved neonatal outcomes in patients with preterm PROM. These findings suggest that the combination of anti-microbial agents (ceftriaxone, clarithromycin, and metronidazole) may improve perinatal outcome in preterm PROM.

Compensatory fetal membrane mechanisms between biglycan and decorin in inflammation

Preterm premature rupture of fetal membranes (PPROM) is associated with infection, and is one of the most common causes of preterm birth. Abnormal expression of biglycan and decorin, two extracellular matrix proteoglycans, leads to preterm birth and aberrant fetal membrane morphology and signaling in the mouse. In humans and mice, decorin dysregulation is associated with inflammation in PPROM. We therefore investigated the link between biglycan and decorin and inflammation in fetal membranes using mouse models of intraperitoneal Escherichia coli injections superimposed on genetic biglycan and decorin deficiencies. We assessed outcomes in vivo as well as in vitro using quantitative PCR, Western blotting, and enzyme-linked immunosorbent assays. Our results suggest that biglycan and decorin compensate for each other in the fetal membranes, but lose the ability to do so under inflammation, leading to decreased latency to preterm birth. Furthermore, our findings suggest that biglycan and decorin play discrete roles in fetal membrane signaling pathways during inflammation, leading to changes in the abundance of MMP8 and collagen α1VI, two components of the fetal membrane extracellular matrix that influence the pathophysiology of PPROM. In summary, these findings underline the importance of biglycan and decorin as targets for the manipulation of fetal membrane extracellular matrix stability in the context of inflammation.

Pentraxin-3 concentration in the amniotic fluid of women at term, in spontaneous preterm labor and when not in labor

OBJECTIVE

To evaluate the concentration of PTX3 in amniotic fluid (AF) during the final weeks of normal pregnancies and in pregnancies complicated by preterm delivery (PTD).

STUDY DESIGN

A cross-sectional study was conducted with 95 pregnant women followed to term and 25 who presented with PTD. Samples of AF from all patients were obtained during cesarean section and the PTX3 concentration was determined by enzyme immunoassay (ELISA). Maternal characteristics were compared by ANOVA and the Kruskal-Wallis and Chi square tests. Comparison between PTX3 concentrations in the "PTD in labor" and "PTD not in labor" groups were performed using the Mann-Whitney test. A p value <0.05 was considered statistically significant.

RESULTS

Regarding term pregnancies, PTX3 concentrations were not statistically different across the period studied (37 weeks to 40 weeks). Among preterm pregnancies, those in preterm labor (PTL) presented higher PTX3 levels than those not in labor (p=0.001) and the risk of occurrence of PTL increased by 1% with a rise of 1pg/mL in PTX3.

CONCLUSION

PTX3 is a physiological constituent of the AF, and its concentration is elevated in the presence of spontaneous PTL, reinforcing the theory that PTX3 plays a role in the innate immune response during gestational complications associated with infectious/inflammatory conditions.

Gene expression and protein localization of TLR-1, -2, -4 and -6 in amniochorion membranes of pregnancies complicated by histologic chorioamnionitis

OBJECTIVES

To determine whether histologic chorioamnionitis is associated with changes in gene expression of TLR-1, -2, -4 and -6, and to describe the localization of these receptors in fetal membranes.

STUDY DESIGN

A total of 135 amniochorion membranes with or without histologic chorioamnionitis from preterm or term deliveries were included. Fragments of membranes were submitted to total RNA extraction. RNA was reverse transcribed and the quantification of TLRs expression measured by real time PCR.

RESULTS

All amniochorion membranes expressed TLR-1 and TLR-4, whereas 99.1% of membranes expressed TLR-2 and 77.4% expressed TLR-6. TLR-1 and TLR-2 expressions were significantly higher in membranes with histologic chorioamnionitis as compared to membranes without chorioamnionitis in preterm pregnancies (p=0.003 and p<0.001, respectively). Among the membranes of term pregnancies there were no differences in the expressions of such receptors regardless of inflammatory status. Regarding TLR-4 and TLR-6 expression, there was no difference among membranes with or without histologic chorioamnionitis, regardless gestational age at delivery. TLR-1, TLR-2, TLR-4 and TLR-6 expressions were observed in amniotic epithelial, chorionic and decidual cells.

CONCLUSION

Amniochorion membranes express TLR-1, TLR-2, TLR-4 and TLR-6 and increased expression of TLR-1 and TLR-2 is related to the presence of histologic chorioamnionitis in preterm pregnancies. This study provides further evidence that amniochorion membranes act as a mechanical barrier to microorganisms and as components of the innate immune system.

Perinatal Outcome in Pregnancies with Extreme Preterm Premature Rupture of Membranes (Mid-Trimester PROM)

OBJECTIVES

Preterm premature rupture of membranes (PPROM) is defined as the rupture of fetal membranes before 37 weeks. Extreme PPROM occurs before 26 weeks' gestation and can result in perinatal morbidity and mortality. The aim of this study was to study the perinatal outcomes of mothers with extreme PPROM.

METHODS

A retrospective cohort study of 44 consecutive pregnant women, presenting with PPROM before 26 weeks' gestation, was conducted from January 2006 to December 2011 at Sultan Qaboos University Hospital, Oman. Maternal and neonatal information was collected from medical records, and delivery and neonatal unit registries. Women with PPROM presenting after 26 weeks' gestation, those with multiple gestations, or other types of preterm deliveries were excluded from the study.

RESULTS

Of the 44 preterm infants admitted to the Neonatal Intensive Care Unit, 24 (55%) survived, 7 (16%) died within 24 hours of birth, 9 (20%) were miscarried, and 4 (9%) were stillbirths. Neonatal sepsis and pulmonary hypoplasia were the major causes of death. Neonatal complications among the surviving infants included prematurity in 11 (46%), respiratory distress syndrome in 19 (79%), sepsis in 12 (50%), and low birth weight in 11 (46%). The neonatal survival rate was significantly associated with the gestational age at delivery but not with the gestational age upon rupture of membranes.

CONCLUSION

Extreme PPROM was associated with adverse perinatal outcomes. The results of this study will help obstetricians and neonatologists in counselling couples experiencing PPROM. Future studies of long-term neonatal morbidity should have larger sample sizes and include more hospitals.

The antibiotic treatment of PPROM study: systemic maternal and fetal markers and perinatal outcomes

OBJECTIVE

We sought to correlate maternal and cord blood cytokine and intercellular adhesion molecule-1 levels with antibiotic exposure and perinatal outcomes after conservatively managed preterm premature rupture of the membranes.

STUDY DESIGN

Conservatively managed women with preterm premature rupture of the membranes at 24-32 weeks had blood sampling at randomization (n = 222) and delivery (n = 121). Plasma from these, and umbilical cord blood (n = 196), was stored at -70°C. Interleukin (IL)-6, IL-10, granulocyte colony-stimulating factor (G-CSF), tumor necrosis factor-α, and intercellular adhesion molecule-1 levels were assessed for associations with antibiotic treatment, latency, amnionitis, neonatal sepsis, pneumonia, and composite neonatal morbidity.

RESULTS

Cord blood IL-6 and G-CSF were higher than maternal levels. Antibiotic treatment lowered only maternal G-CSF (P = .01). Elevated maternal cytokine levels were associated with delivery within 7 days and with development of chorioamnionitis. All umbilical cord blood markers were increased with amnionitis (P ≤ .01 for each). No maternal marker was associated with neonatal morbidities. Cord G-CSF and IL-6 were increased with neonatal sepsis within 72 hours of birth (P = .004 for both), and with composite neonatal morbidity (P = .001 and .002, respectively). Maternal and umbilical cord cytokine levels demonstrated low predictive values for perinatal outcomes.

CONCLUSION

Umbilical cord blood cytokine values are higher than maternal levels, suggesting significant fetal/placental contribution. Maternal and umbilical cord cytokine levels are not adequately predictive to be used clinically.

A genetic association study of maternal and fetal candidate genes that predispose to preterm prelabor rupture of membranes (PROM)

OBJECTIVE

We sought to determine whether maternal/fetal single-nucleotide polymorphisms (SNPs) in candidate genes are associated with preterm prelabor rupture of membranes (pPROM).

STUDY DESIGN

A case-control study was conducted in patients with pPROM (225 mothers and 155 fetuses) and 599 mothers and 628 fetuses with a normal pregnancy; 190 candidate genes and 775 SNPs were studied. Single locus/haplotype association analyses were performed; false discovery rate was used to correct for multiple testing (q* = 0.15).

RESULTS

First, a SNP in tissue inhibitor of metalloproteinase 2 in mothers was significantly associated with pPROM (odds ratio, 2.12; 95% confidence interval, 1.47-3.07; P = .000068), and this association remained significant after correction for multiple comparisons. Second, haplotypes for Alpha 3 type IV collagen isoform precursor in the mother were associated with pPROM (global P = .003). Third, multilocus analysis identified a 3-locus model, which included maternal SNPs in collagen type I alpha 2, defensin alpha 5 gene, and endothelin 1.

CONCLUSION

DNA variants in a maternal gene involved in extracellular matrix metabolism doubled the risk of pPROM.

Management of premature prelabor rupture of the membranes

Premature prelabor rupture of the fetal membranes affects about 3% of pregnancies. The cause is usually infection, especially at earlier gestations. The prognosis and the risks of delivery are both much worse at earlier gestations. Before viable pregnancy, termination may be offered. Once the fetus is viable, steroids to mature the fetal lungs and antibiotics to reduce infection are the mainstays of treatment. Delivery is recommended in the presence of signs of clear-cut infection at early gestational ages. At later ones, balancing the risks of infection from conservative treatment against the risk of prematurity from delivery is difficult. Published trials to date have not given clear guidance, but a number are ongoing.

Protocol for the immediate delivery versus expectant care of women with preterm prelabour rupture of the membranes close to term (PPROMT) Trial [ISRCTN44485060]

Background

Preterm prelabour rupture of membranes (PPROM) complicates up to 2% of all pregnancies and is the cause of 40% of all preterm births. The optimal management of women with PPROM prior to 37 weeks, is not known. Furthermore, diversity in current clinical practice suggests uncertainty about the appropriate clinical management.

There are two options for managing PPROM, expectant management (a wait and see approach) or early planned birth. Infection is the main risk for women in which management is expectant. This risk need to be balanced against the risk of iatrogenic prematurity if early delivery is planned. The different treatment options may also have different health care costs. Expectant management results in prolonged antenatal hospitalisation while planned early delivery may necessitate intensive care of the neonate for problems associated with prematurity.

Methods/Design

We aim to evaluate the effectiveness of early planned birth compared with expectant management for women with PPROM between 34 weeks and 36⁶ weeks gestation, in a randomised controlled trial. A secondary aim is a cost analysis to establish the economic impact of the two treatment options and establish the treatment preferences of women with PPROM close to term.

The early planned birth group will be delivered within 24 hours according to local management protocols. In the expectant management group birth will occur after spontaneous labour, at term or when the attending clinician feels that birth is indicated according to usual care. Approximately 1812 women with PPROM at 34–36⁶ weeks gestation will be recruited for the trial.

The primary outcome of the study is neonatal sepsis. Secondary infant outcomes include respiratory distress, perinatal mortality, neonatal intensive care unit admission, assisted ventilation and early infant development. Secondary maternal outcomes include chorioamnionitis, postpartum infection treated with antibiotics, antepartum haemorrhage, induction of labour, mode of delivery, maternal satisfaction with care, duration of hospitalisation, and maternal wellbeing at four months postpartum.

Discussion

This trial will provide evidence on the optimal care for women with PPROM close to term (34–37 weeks gestation). Consideration of both the clinical and economic sequelae of the management of PPROM will enable informed decision making and guideline development.

Laminar necrosis of placental membranes: a histologic sign of uteroplacental hypoxia

Laminar necrosis of placental membranes (LN), a band of coagulative necrosis at the choriodecidual interphase, is a histologic lesion of unclear pathogenesis that has been reported in placentas from preeclampsia, preterm premature rupture of membranes, and preterm abruption. To better explore other possible correlations of LN, we performed a retrospective case-control study in which data on pregnancy risks and outcomes, neonate conditions, and placental gross, routine microscopic, and selected immunohistochemistry examinations in 52 consecutive cases of LN were compared with 52 gestational age-matched control cases without LN. Maternal hypertensive disorders and combinations of 2 or more maternal, fetal, neonatal, or placental conditions known to be potentially associated with uteroplacental hypoxia were more prevalent in patients with LN than in control patients. By immunohistochemistry, LN areas were positive for complement 9 (marker of necrosis) and negative for active caspase 3 (marker of irreversible apoptosis), nitrotyrosine residues (marker of oxidative stress), and Ki-67 (proliferation marker), thus confirming their necrotic rather than apoptotic nature. However, LN areas were flanked by caspase 3 positivity, and the positivity for nitrotyrosine residues was more pronounced in the decidua and mesenchyme in the same membrane rolls as LN, which indicates a probable role of apoptosis and oxidative stress in the development of LN. Based on these immunohistochemical results and clinicopathologic correlations, we believe LN should be recognized and reported as a hypoxic placental lesion.

Premature rupture of membranes and early mortality among triplets in the United States

OBJECTIVES

We investigated the relationship between premature rupture of the membranes (PROM) and early mortality among triplets in the United States.

STUDY DESIGN

Analysis was conducted on matched and linked triplet sets born to mothers in the United States between 1995 and 1997. The generalized estimating equation framework was used to generate odds ratios after capturing the effects of sibling correlations within triplet clusters.

RESULTS

Triplets exposed to PROM were twice as likely to experience stillbirth (OR=2.17, 95% CI [1.26-3.41]), neonatal death (OR=2.23, 95% CI [1.70-3.0]) and infant death (OR=2.21, 95% CI [1.72-2.85]), as compared to those who did not. The population-attributable risk for early mortality due to PROM was 11-12%.

CONCLUSIONS

Triplets associated with PROM had a significantly higher level of early mortality than those without. Assuming a causal relationship, 11-12% of all early deaths among triplets in the United States are accounted for by PROM.

What we have learned regarding antibiotic therapy for the reduction of infant morbidity after preterm premature rupture of the membranes

Preterm premature rupture of the membranes (pPROM) is responsible for approximately one third of the over 450,000 preterm births occurring in the United States annually. In this manuscript, we summarize the outcomes and analyses related to the National Institute of Child Health and Human Development Maternal Fetal Medicine Units Network (NICHD-MFMU) network multicenter trial of antibiotics to reduce infant morbidity after pPROM. Based on evident reduction in gestational age dependent and infectious infant morbidity, we provide the rationale for aggressive intravenous and oral, broad spectrum Ampicillin/Amoxicillin, and Erythromycin therapy during conservative management of pPROM before 32 weeks' gestation. We further review the histopathologic correlates to pPROM, to antibiotic treatment, and to perinatal outcome, and discuss the relationships between maternal and neonatal cytokine levels intercellular adhesion molecule, and other clinical and plasma markers regarding perinatal morbidity. The use and limitations of ultrasound and vaginally collected amniotic fluid pulmonary maturity assessment are discussed.