Evaluation of Hypoglycemia in Neonates of Women at Risk for Late Preterm Delivery: An Antenatal Late Preterm Steroids Trial Cohort Study.

OBJECTIVE: In the antenatal late preterm steroids (ALPS) trial betamethasone significantly decreased short-term neonatal respiratory morbidity but increased the risk of neonatal hypoglycemia, diagnosed only categorically (<40 mg/dL). We sought to better characterize the nature, duration, and treatment for hypoglycemia. STUDY DESIGN: Secondary analysis of infants from ALPS, a multicenter trial randomizing women at risk for late preterm delivery to betamethasone or placebo. This study was a reabstraction of all available charts from the parent trial, all of which were requested. Unreviewed charts included those lost to follow-up or from sites not participating in the reabstraction. Duration of hypoglycemia (<40 mg/dL), lowest value and treatment, if any, were assessed by group. Measures of association and regression models were used where appropriate. RESULTS: Of 2,831 randomized, 2,609 (92.2%) were included. There were 387 (29.3%) and 223 (17.3%) with hypoglycemia in the betamethasone and placebo groups, respectively (relative risk [RR]: 1.69, 95% confidence interval [CI]: 1.46-1.96). Hypoglycemia generally occurred in the first 24 hours in both groups: 374/385 (97.1%) in the betamethasone group and 214/222 (96.4%) in the placebo group (p = 0.63). Of 387 neonates with hypoglycemia in the betamethasone group, 132 (34.1%) received treatment, while 73/223 (32.7%) received treatment in placebo group (p = 0.73). The lowest recorded blood sugar was similar between groups. Most hypoglycemia resolved by 24 hours in both (93.0 vs. 89.3% in the betamethasone and placebo groups, respectively, p = 0.18). Among infants with hypoglycemia in the first 24 hours, the time to resolution was shorter in the betamethasone group (2.80 [interquartile range: 2.03-7.03) vs. 3.74 (interquartile range: 2.15-15.08) hours; p = 0.002]. Persistence for >72 hours was rare and similar in both groups, nine (2.4%, betamethasone) and four (1.9%, placebo, p = 0.18). CONCLUSION: In this cohort, hypoglycemia was transient and most received no treatment, with a quicker resolution in the betamethasone group. Prolonged hypoglycemia was uncommon irrespective of steroid exposure. KEY POINTS: · Hypoglycemia was transient and approximately two-thirds received no treatment.. · Neonates in the ALPS trial who received betamethasone had a shorter time to resolution than those with hypoglycemia in the placebo group.. · Prolonged hypoglycemia occurred in approximately 2 out of 100 late preterm newborns, irrespective of antenatal steroid exposure..

Association Between Features of Spontaneous Late Preterm Labor and Late Preterm Birth.

OBJECTIVE: This study aimed to evaluate the association between clinical and examination features at admission and late preterm birth. STUDY DESIGN: The present study is a secondary analysis of a randomized trial of singleton pregnancies at 340/7 to 365/7 weeks' gestation. We included women in spontaneous preterm labor with intact membranes and compared them by gestational age at delivery (preterm vs. term). We calculated a statistical cut-point optimizing the sensitivity and specificity of initial cervical dilation and effacement at predicting preterm birth and used multivariable regression to identify factors associated with late preterm delivery. RESULTS: A total of 431 out of 732 (59%) women delivered preterm. Cervical dilation ≥ 4 cm was 60% sensitive and 68% specific for late preterm birth. Cervical effacement ≥ 75% was 59% sensitive and 65% specific for late preterm birth. Earlier gestational age at randomization, nulliparity, and fetal malpresentation were associated with late preterm birth. The final regression model including clinical and examination features significantly improved late preterm birth prediction (81% sensitivity, 48% specificity, area under the curve = 0.72, 95% confidence interval [CI]: 0.68-0.75, and p-value < 0.01). CONCLUSION: Four in 10 women in late-preterm labor subsequently delivered at term. Combination of examination and clinical features (including parity and gestational age) improved late-preterm birth prediction.

Antenatal Betamethasone for Women at Risk for Late Preterm Delivery.

BACKGROUND: Infants who are born at 34 to 36 weeks of gestation (late preterm) are at greater risk for adverse respiratory and other outcomes than those born at 37 weeks of gestation or later. It is not known whether betamethasone administered to women at risk for late preterm delivery decreases the risks of neonatal morbidities. METHODS: We conducted a multicenter, randomized trial involving women with a singleton pregnancy at 34 weeks 0 days to 36 weeks 5 days of gestation who were at high risk for delivery during the late preterm period (up to 36 weeks 6 days). The participants were assigned to receive two injections of betamethasone or matching placebo 24 hours apart. The primary outcome was a neonatal composite of treatment in the first 72 hours (the use of continuous positive airway pressure or high-flow nasal cannula for at least 2 hours, supplemental oxygen with a fraction of inspired oxygen of at least 0.30 for at least 4 hours, extracorporeal membrane oxygenation, or mechanical ventilation) or stillbirth or neonatal death within 72 hours after delivery. RESULTS: The primary outcome occurred in 165 of 1427 infants (11.6%) in the betamethasone group and 202 of 1400 (14.4%) in the placebo group (relative risk in the betamethasone group, 0.80; 95% confidence interval [CI], 0.66 to 0.97; P=0.02). Severe respiratory complications, transient tachypnea of the newborn, surfactant use, and bronchopulmonary dysplasia also occurred significantly less frequently in the betamethasone group. There were no significant between-group differences in the incidence of chorioamnionitis or neonatal sepsis. Neonatal hypoglycemia was more common in the betamethasone group than in the placebo group (24.0% vs. 15.0%; relative risk, 1.60; 95% CI, 1.37 to 1.87; P<0.001). CONCLUSIONS: Administration of betamethasone to women at risk for late preterm delivery significantly reduced the rate of neonatal respiratory complications. (Funded by the National Heart, Lung, and Blood Institute and the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ClinicalTrials.gov number, NCT01222247.).

Cholinergic regulation of epithelial sodium channels in rat alveolar type 2 epithelial cells.

We and others have shown that epithelial Na(+) channels (ENaC) in alveolar type 2 (AT2) cells are activated by ß2 agonists, steroid hormones, elevated oxygen tension, and by dopamine. Although acetylcholine receptors (AChRs) have been previously described in the lung, there are few reports of whether cholinergic agonists alter sodium transport in the alveolar epithelium. Therefore, we investigated how cholinergic receptors regulate ENaC activity in primary cultures of rat AT2 cells using cell-attached patch-clamp recordings to assess ENaC activity. We found that the muscarinic agonists, carbachol (CCh) and oxotremorine, activated ENaC in a dose-dependent manner but that nicotine did not. CCh-induced activation of ENaC was blocked by atropine. Western blotting and immunohistochemistry suggested that muscarinic M2 and M3 receptors (mAChRs) but not nicotinic receptors were present in AT2 cells. Endogenous RhoA and GTP-RhoA increased in response to CCh and the increase was reduced by pretreatment with atropine. We showed that Y-27632, an inhibitor of Rho-associated protein kinase (ROCK), abolished endogenous ENaC activity and inhibited the activation of ENaC by CCh. We also showed that ROCK signaling was necessary for ENaC stability in 2F3 cells, a model for AT2 cells. Our results showed that muscarinic agonists activated ENaC in rat AT2 cells through M2 and/or M3 mAChRs probably via a RhoA/ROCK signaling pathway.

Maternal smoking during pregnancy and failure of the georgia first grade criterion-referenced competency test.

BACKGROUND: Maternal smoking during pregnancy (MSDP) has been reported to be associated with impaired measures of cognitive function, but it remains unclear whether exposure to MSDP has an impact upon offspring school performance. We examined the association between MSDP and failure of the Criterion-Referenced Competency Tests (CRCT) among Georgia first grade students. METHODS: A retrospective cohort was created by deterministically linking 331 531 children born in Georgia from 1998 to 2002 (inclusive) to their individual CRCT education records from 2005 to 2009. We evaluated the association between MSDP (yes/no) and failure of the CRCT Reading, English/Language Arts (ELA), and Mathematics tests, with adjustment for maternal and child sociodemographic characteristics and birth outcomes. Log-binomial models estimated the risk ratios and 95% confidence intervals. Conditional models were fitted to paired sibling data. RESULTS: MSDP was associated with CRCT failure with an adjusted risk ratios for Reading: 1.16 [95% CI 1.12, 1.21]; ELA: 1.12 [95%CI 1.10, 1.15]; and Mathematics: 1.13 [95%CI 1.10, 1.16]. The association remained significant in paired sibling analyses. CONCLUSIONS: MSDP may have independent long-term effects on offspring school performance, which does not appear to be through smoking-related adverse birth outcomes.

The contribution of epithelial sodium channels to alveolar function in health and disease.

Amiloride-sensitive epithelial sodium channels (ENaC) play an important role in lung sodium transport. Sodium transport is closely regulated to maintain an appropriate fluid layer on the alveolar surface. Both alveolar type I and II cells have several different sodium-permeable channels in their apical membranes that play a role in normal lung physiology and pathophysiology. In many epithelial tissues, ENaC is formed from three subunit proteins: alpha, beta, and gamma ENaC. Part of the diversity of sodium-permeable channels in lung arises from assembling different combinations of these subunits to form channels with different biophysical properties and different mechanisms for regulation. Thus, lung epithelium has enormous flexibility to alter the magnitude of salt and water transport. In lung, ENaC is regulated by many transmitter and hormonal agents. Regulation depends upon the type of sodium channel but involves controlling the number of apical channels and/or the activity of individual channels.

Nadph oxidase regulates alveolar epithelial sodium channel activity and lung fluid balance in vivo via O⁻2 signaling.

To define roles for reactive oxygen species (ROS) and epithelial sodium channel (ENaC) in maintaining lung fluid balance in vivo, we used two novel whole animal imaging approaches. Live X-ray fluoroscopy enabled quantification of air space fluid content of C57BL/6J mouse lungs challenged by intratracheal (IT) instillation of saline; results were confirmed by using conventional lung wet-to-dry weight ratios and Evans blue as measures of pulmonary edema. Visualization and quantification of ROS produced in lungs was performed in mice that had been administered a redox-sensitive dye, hydro-Cy7, by IT instillation. We found that inhibition of NADPH oxidase with a Rac-1 inhibitor, NSC23766, resulted in alveolar flooding, which correlated with a decrease in lung ROS production in vivo. Consistent with a role for Nox2 in alveolar fluid balance, Nox2(-/-) mice showed increased retention of air space fluid compared with wild-type controls. Interestingly, fluoroscopic analysis of C57BL/6J lungs IT instilled with LPS showed an acute stimulation of lung fluid clearance and ROS production in vivo that was abrogated by the ROS scavenger tetramethylpiperidine-N-oxyl (TEMPO). Acute application of LPS increased the activity of 20 pS nonselective ENaC channels in rat type 1 cells; the average number of channel and single-channel open probability (NPo) increased from 0.14 ± 0.04 to 0.62 ± 0.23. Application of TEMPO to the same cell-attached recording caused an immediate significant decrease in ENaC NPo to 0.04 ± 0.03. These data demonstrate that, in vivo, ROS has the capacity to stimulate lung fluid clearance by increasing ENaC activity.

ß-Adrenergic agonists differentially regulate highly selective and nonselective epithelial sodium channels to promote alveolar fluid clearance in vivo.

ß-Adrenergic receptors (ß-AR) increase epithelial sodium channel (ENaC) activity to promote lung fluid clearance. However, the effect of selective ß-AR agonist on highly selective cation (HSC) channels or nonselective cation (NSC) channels in alveolar type 1 (T1) and type 2 (T2) cells is unknown. We hypothesized that stimulation with ß(1)-AR agonist (denopamine) or ß(2)-AR agonist (terbutaline) would increase HSC and/or NSC channel activity in alveolar epithelial cells. We performed single-channel measurements from T1 and T2 cells accessed from rat lung slices. Terbutaline (20 µM) increased HSC ENaC activity (open probability, NP(o)) in T1 (from 0.96 ± 0.61 to 1.25 ± 0.71, n = 5, P <0.05) and T2 cells (from 0.28 ± 0.14 to 1.0 ± 0.30, n = 8, P = 0.02). Denopamine (20 µM) increased NSC NP(o) in T1 cells (from 0.34 ± 0.09 to 0.63 ± 0.14, n = 7, P = 0.02) and in T2 cells (from 0.47 ± 0.09 to 0.68 ± 0.10, P = 0.004). In vivo X-ray imaging of lung fluid clearance and ICI 118,551 selective inhibition of ß(2)-ARs confirmed patch-clamp findings. cAMP concentrations increased following treatment with denopamine or terbutaline (n = 3, P < 0.002). The effects of systemic (intraperitoneal, IP) and local (intratracheal, IT) modes of delivery on lung fluid clearance were assessed. IT delivery of denopamine promoted alveolar flooding, whereas IP delivery promoted delayed fluid clearance. In summary, ß-AR agonists differentially regulate HSC and NSC in T1 and T2 cells to promote lung fluid clearance in vivo, and the mode of drug delivery is critical for maximizing ß-AR agonist efficacy.

Morbidity and mortality in late preterm infants with severe hypoxic respiratory failure on extra-corporeal membrane oxygenation.

OBJECTIVES: To evaluate morbidity, mortality, and associated risk factors in late preterm term infants (34-0/7 to 36-6/7 weeks) requiring extra-corporeal membrane oxygenation (ECMO). STUDY DESIGN: We reviewed 21,218 neonatal ECMO runs in Extra-corporeal Life Support Organization registry data from 1986-2006. Infants were divided in 3 groups: late preterm (34-0/7 to 36-6/7 weeks), early-term (37-0/7 to 38-6/7 weeks), and full-term (39-0/7 to 42-6/7 weeks). RESULTS: There were 14,528 neonatal ECMO runs that met inclusion criteria. Late preterm infants experienced the highest mortality rate on ECMO (late preterm, 26.2%; early-term, 18%; full-term, 11.2%; P < .001) and had longer ECMO runs; they also had higher rates of serious complications. Gestational age was a highly significant predictor for mortality. Late preterm infants with a primary diagnosis of sepsis and persistent pulmonary hypertension had 3-fold higher risk of mortality on ECMO than infants with meconium aspiration. CONCLUSION: Late preterm infants treated with ECMO have higher morbidity and mortality rates than term infants. This underscores the need for special consideration of this vulnerable population in the diagnosis and treatment of hypoxic respiratory failure.

Rac1-mediated NADPH oxidase release of O2- regulates epithelial sodium channel activity in the alveolar epithelium.

We examine whether alveolar cells can control release of O(2)(-) through regulated NADPH oxidase (NOX) 2 (NOX2) activity to maintain lung fluid homeostasis. Using FACS to purify alveolar epithelial cells, we show that type 1 cells robustly express each of the critical NOX components that catalyze the production of O(2)(-) (NOX2 or gp91(phox), p22(phox), p67(phox), p47(phox), and p40(phox) subunits) as well as Rac1 at substantially higher levels than type 2 cells. Immunohistochemical labeling of lung tissue shows that Rac1 expression is cytoplasmic and resides near the apical surface of type 1 cells, whereas NOX2 coimmunoprecipitates with epithelial sodium channel (ENaC). Since Rac1 is a known regulator of NOX2, and hence O(2)(-) release, we tested whether inhibition or activation of Rac1 influenced ENaC activity. Indeed, 1 microM NSC23766 inhibition of Rac1 decreased O(2)(-) output in lung cells and significantly decreased ENaC activity from 0.87 +/- 0.16 to 0.52 +/- 0.16 [mean number of channels (N) and single-channel open probability (P(o)) (NP(o)) +/- SE, n = 6; P < 0.05] in type 2 cells. NSC23766 (10 microM) decreased ENaC NP(o) from 1.16 +/- 0.27 to 0.38 +/- 0.10 (n = 6 in type 1 cells). Conversely, 10 ng/ml EGF (a known stimulator of both Rac1 and O(2)(-) release) increased ENaC NP(o) values in both type 1 and 2 cells. NP(o) values increased from 0.48 +/- 0.21 to 0.91 +/- 0.28 in type 2 cells (P < 0.05; n = 10). In type 1 cells, ENaC activity also significantly increased from 0.40 +/- 0.15 to 0.60 +/- 0.23 following EGF treatment (n = 7). Sequestering O(2)(-) using 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) compound prevented EGF activation of ENaC in both type 1 and 2 cells. In conclusion, we report that Rac1-mediated NOX2 activity is an important component in O(2)(-) regulation of ENaC.

Association of Gestational Diabetes Mellitus With Neonatal Respiratory Morbidity.

OBJECTIVE: To assess neonatal respiratory morbidity in pregnancies with and without gestational diabetes mellitus (GDM) at imminent risk of late preterm delivery in a modern U.S. cohort. METHODS: Secondary analysis of a randomized placebo-controlled trial in which women with singleton pregnancies at high risk for delivery between 34 0/7 and 36 5/7 weeks of gestation were allocated to betamethasone or placebo. The primary outcome for the trial and this secondary analysis was a composite outcome of neonatal respiratory morbidity in the first 72 hours of life. Secondary outcomes included neonatal severe respiratory complications, neonatal intensive care unit (NICU) admission greater than or equal to 3 days, and hyperbilirubinemia. We examined associations between neonatal morbidities and GDM status after adjustment for baseline differences and study group allocation using modified Poisson regression. Models incorporating a product interaction term between GDM status and treatment arm (betamethasone or placebo) were also evaluated. RESULTS: Of the 2,831 women enrolled in the trial, 306 (10.8%) had GDM. Women with GDM were significantly older and were more likely to be parous and to have hypertensive disorders of pregnancy than those without GDM, but they were similar regarding race, gestational age at randomization (35.6 weeks) and at delivery (36.1 weeks), and study group assignment. Neonates born to women with GDM were no more likely to meet the primary outcome than those born to women without GDM, even after adjusting for differences in age, parity, and hypertensive disorders of pregnancy (12.1% vs 13.1%, adjusted RR 0.84; 95% CI 0.61-1.17), nor were they more likely to have severe respiratory complications or prolonged NICU admission. CONCLUSION: Maternal GDM is not associated with increased neonatal respiratory morbidity in this study population who were at high risk for late preterm birth.

Cost-effectiveness of Antenatal Corticosteroid Therapy vs No Therapy in Women at Risk of Late Preterm Delivery: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Administration of corticosteroids to women at high risk for delivery in the late preterm period (34-36 weeks' gestation) improves short-term neonatal outcomes. The cost implications of this intervention are not known. Objective: To compare the cost-effectiveness of treatment with antenatal corticosteroids with no treatment for women at risk for late preterm delivery. Design, Setting, and Participants: This secondary analysis of the Antenatal Late Preterm Steroids trial, a multicenter randomized clinical trial of antenatal corticosteroids vs placebo in women at risk for late preterm delivery conducted from October 30, 2010, to February 27, 2015. took a third-party payer perspective. Maternal costs were based on Medicaid rates and included those of betamethasone, as well as the outpatient visits or inpatient stay required to administer betamethasone. All direct medical costs for newborn care were included. For infants admitted to the neonatal intensive care unit, comprehensive daily costs were stratified by the acuity of respiratory illness. For infants admitted to the regular newborn nursery, nationally representative cost estimates from the literature were used. Effectiveness was measured as the proportion of infants without the primary outcome of the study: a composite of treatment in the first 72 hours of continuous positive airway pressure or high-flow nasal cannula for 2 hours or more, supplemental oxygen with a fraction of inspired oxygen of 30% or more for 4 hours or more, and extracorporeal membrane oxygenation or mechanical ventilation. This secondary analysis was initially started in June 2016 and revision of the analysis began in May 2017. Exposures: Betamethasone treatment. Main Outcomes and Measures: Incremental cost-effectiveness ratio. Results: Costs were determined for 1426 mother-infant pairs in the betamethasone group (mean [SD] maternal age, 28.6 [6.3] years; 827 [58.0%] white) and 1395 mother-infant pairs in the placebo group (mean [SD] maternal age, 27.9 [6.2] years; 794 [56.9%] white). Treatment with betamethasone was associated with a total mean (SD) woman-infant-pair cost of $4681 ($5798), which was significantly less than the mean (SD) amount of $5379 ($8422) for women and infants in the placebo group (difference, $698; 95% CI, $186-$1257; P = .02). The Antenatal Late Preterm Steroids trial determined that betamethasone use is effective: respiratory morbidity decreased by 2.9% (95% CI, -0.5% to -5.4%). Thus, the cost-effectiveness ratio was -$23 986 per case of respiratory morbidity averted. Inspection of the bootstrap replications confirmed that treatment was the dominant strategy in 5000 samples (98.8%). Sensitivity analyses showed that these results held under most assumptions. Conclusions and Relevance: The findings suggest that antenatal betamethasone treatment is associated with a statistically significant decrease in health care costs and with improved outcomes; thus, this treatment may be an economically desirable strategy.

Elective cesarean section: its impact on neonatal respiratory outcome.

Physiologic events in the last few weeks of pregnancy coupled with the onset of spontaneous labor are accompanied by changes in the hormonal milieu of the fetus and its mother, resulting in preparation of the fetus for neonatal transition. Rapid clearance of fetal lung fluid is a key part of these changes, and is mediated in large part by transepithelial sodium reabsorption through amiloride-sensitive sodium channels in the alveolar epithelial cells, with only a limited contribution from mechanical factors and Starling forces. This article discusses the respiratory morbidity associated with elective cesarean section, the physiologic mechanisms underlying fetal lung fluid absorption, and potential strategies for facilitating neonatal transition when infants are delivered by elective cesarean section before the onset of spontaneous labor.