Respiratory outcome in preterm small for gestational age fetuses with or without abnormal umbilical artery Doppler and/or maternal hypertension

Pulmonary vascular reactivity in growth restricted fetuses using computational modelling and machine learning analysis of fetal Doppler waveforms

The aim of this study was to investigate the pulmonary vasculature in baseline conditions and after maternal hyperoxygenation in growth restricted fetuses (FGR). A prospective cohort study of singleton pregnancies including 97 FGR and 111 normally grown fetuses was carried out. Ultrasound Doppler of the pulmonary vessels was obtained at 24-37 weeks of gestation and data were acquired before and after oxygen administration. After, Machine Learning (ML) and a computational model were used on the Doppler waveforms to classify individuals and estimate pulmonary vascular resistance (PVR). Our results showed lower mean velocity time integral (VTI) in the main pulmonary and intrapulmonary arteries in baseline conditions in FGR individuals. Delta changes of the main pulmonary artery VTI and intrapulmonary artery pulsatility index before and after hyperoxygenation were significantly greater in FGR when compared with controls. Also, ML identified two clusters: A (including 66% controls and 34% FGR) with similar Doppler traces over time and B (including 33% controls and 67% FGR) with changes after hyperoxygenation. The computational model estimated the ratio of PVR before and after maternal hyperoxygenation which was closer to 1 in cluster A (cluster A 0.98 ± 0.33 vs cluster B 0.78 ± 0.28, p = 0.0156). Doppler ultrasound allows the detection of significant changes in pulmonary vasculature in most FGR at baseline, and distinct responses to hyperoxygenation. Future studies are warranted to assess its potential applicability in the clinical management of FGR.

Antenatal corticosteroids in specific groups at risk of preterm birth: a systematic review

OBJECTIVE

This study aimed to synthesise available evidence on the efficacy of antenatal corticosteroid (ACS) therapy among women at risk of imminent preterm birth with pregestational/gestational diabetes, chorioamnionitis or fetal growth restriction (FGR), or planned caesarean section (CS) in the late preterm period.

METHODS

A systematic search of MEDLINE, EMBASE, CINAHL, Cochrane Library, Web of Science and Global Index Medicus was conducted for all comparative randomised or non-randomised interventional studies in the four subpopulations on 6 June 2021. Risk of Bias Assessment tool for Non-randomised Studies and the Cochrane Risk of Bias tool were used to assess the risk of bias. Grading of Recommendations Assessment, Development and Evaluations tool assessed the certainty of evidence.

RESULTS

Thirty-two studies involving 5018 pregnant women and 10 819 neonates were included. Data on women with diabetes were limited, and evidence on women undergoing planned CS was inconclusive. ACS use was associated with possibly reduced odds of neonatal death (pooled OR: 0.51; 95% CI: 0.31 to 0.85, low certainty), intraventricular haemorrhage (pooled OR: 0.41; 95% CI: 0.23 to 0.72, low certainty) and respiratory distress syndrome (pooled OR: 0.59; 95% CI: 0.45 to 0.77, low certainty) in women with chorioamnionitis. Among women with FGR, the rates of surfactant use (pooled OR: 0.38; 95% CI: 0.23 to 0.62, moderate certainty), mechanical ventilation (pooled OR: 0.42; 95% CI: 0.26 to 0.66, moderate certainty) and oxygen therapy (pooled OR: 0.48; 95% CI: 0.30 to 0.77, moderate certainty) were probably reduced; however, the rate of hypoglycaemia probably increased (pooled OR: 2.06; 95% CI: 1.27 to 3.32, moderate certainty).

CONCLUSIONS

There is a paucity of evidence on ACS for women who have diabetes. ACS therapy may have benefits in women with chorioamnionitis and is probably beneficial in FGR. There is limited direct trial evidence on ACS efficacy in women undergoing planned CS in the late preterm period, though the totality of evidence suggests it is probably beneficial.

PROSPERO REGISTRATION NUMBER

CRD42021267816.

Antenatal corticosteroids and perinatal outcome in late fetal growth restriction: analysis of prospective cohort

OBJECTIVE

To evaluate the role of antenatal administration of corticosteroids for fetal lung maturation on the short-term perinatal outcome of pregnancy complicated by late fetal growth restriction (FGR).

METHODS

This cohort study was a secondary analysis of a multicenter prospective observational study, the TRUFFLE-2 feasibility study, conducted between 2017 and 2018 in 33 European perinatal centers. The study included women with a singleton pregnancy from 32 + 0 to 36 + 6 weeks of gestation with a fetus considered at risk for FGR, defined as estimated fetal weight (EFW) and/or fetal abdominal circumference < 10^th percentile, or umbilicocerebral ratio (UCR) ≥ 95^th percentile or a drop of more than 40 percentile points in abdominal circumference measurement from the 20-week scan. For the purposes of the current study, we identified women who received a single course of steroids to improve fetal lung maturation before delivery. Each exposed pregnancy was matched with one that did not receive antenatal corticosteroids (ACS) (control), based on gestational age at delivery and birth weight. The primary adverse outcome was a composite of abnormal condition at birth, major neonatal morbidity or perinatal death.

RESULTS

A total of 86 pregnancies that received ACS were matched to 86 controls. The two groups were similar with respect to gestational age (33.1 vs 33.3 weeks), EFW (1673 vs 1634 g) and UCR (0.68 vs 0.62) at inclusion, and gestational age at delivery (35.5 vs 35.9 weeks) and birth weight (1925 vs 1948 g). No significant differences were observed between the exposed and non-exposed groups in the incidence of composite adverse outcome (28% vs 24%; P = 0.73) or any of its elements.

CONCLUSION

The present data do not show a beneficial effect of steroids on short-term outcome of fetuses with late FGR. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A Systematic Review on Outcomes of Preterm Small for Gestational Infants Born to Women With Hypertensive Disorders in Pregnancy

There is a lack of knowledge on the intersection between prematurity, small for gestational age, and hypertensive disorders of pregnancy (HDP). Therefore, the aim of this systematic review was to examine the outcomes of preterm infants who were small for gestational age born to women with HDP. Searches were conducted with no date restriction through the final search date of May 13, 2020, in the following databases: PubMed, Web of Science Core Collection, Cumulative Index of Nursing and Allied Health Literature Plus with Full Text (EBSCOhost), and Embase (Elsevier). A total of 6 studies were eligible for this review. The adjusted odds of mortality and necrotizing enterocolitis were significantly lower in the pregnancy-induced hypertension (PIH)/HDP group than in the non-PIH/HDP group. There was no significant difference in the odds of respiratory distress syndrome, bronchopulmonary dysplasia, and intraventricular hemorrhage between PIH/HDP and non-PIH/HDP groups. There was no significant difference between PIH/HDP and non-PIH/HDP groups in cystic periventricular leukomalacia, retinopathy of prematurity, late-onset sepsis, patent ductus arteriosus, length of hospital stays, duration of supplemental oxygen use, duration of mechanical ventilation, and continuous airway pressure. The studies included in this systematic review demonstrated that PIH/HDP is associated with lower infant mortality and necrotizing enterocolitis.

Antenatal corticosteroids in preterm small-for-gestational age infants: a systematic review and meta-analysis

OBJECTIVE

This study aimed to estimate the effect of antenatal corticosteroid administration on neonatal mortality and morbidity in preterm small-for-gestational age infants through a systematic review and meta-analysis.

DATA SOURCES

A predefined, systematic search was conducted through Ovid MEDLINE, Embase, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trial Registry Platform, and ClinicalTrials.gov yielding 5324 articles from 1970 to 2019.

STUDY ELIGIBILITY CRITERIA

Eligible studies compared neonatal morbidity and mortality among small-for-gestational age infants delivered preterm who received antenatal corticosteroids with those who did not.

METHODS

The primary outcome was neonatal mortality. Secondary outcomes were respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage and periventricular leukomalacia, bronchopulmonary dysplasia or chronic lung disease of prematurity, or neonatal sepsis. We assessed heterogeneity by means of Higgins I² statistic and Cochran's Q test and calculated pooled odds ratios with 95% confidence intervals using random effects models.

RESULTS

A total of 16 observational cohort and case-control studies published from 1995 to 2018 met the selection criteria for the systematic review and included 8989 preterm small-for-gestational age infants. Antenatal corticosteroid administration was explicitly reported among 8376 small-for-gestational age infants; 4631 (55.3%) received antenatal corticosteroids and 3741 (44.7%) did not. Of note, 13 studies including 6387 preterm small-for-gestational age infants were then included in the meta-analysis. Neonatal mortality was significantly lower among infants who received antenatal corticosteroids than those who did not (12 studies: 12.8% vs 15.1%; pooled odds ratio, 0.63; 95% confidence interval, 0.46-0.86), with significant heterogeneity between studies (I²=55.1%; P=.011). There was no significant difference in respiratory distress syndrome (12 studies: odds ratio, 0.89; 95% confidence interval, 0.69-1.15), necrotizing enterocolitis (7 studies: odds ratio, 0.93; 95% confidence interval, 0.70-1.22), intraventricular hemorrhage and periventricular leukomalacia (10 studies: odds ratio, 0.82; 95% confidence interval, 0.56-1.20), bronchopulmonary dysplasia or chronic lung disease of prematurity (8 studies: odds ratio, 1.11; 95% confidence interval, 0.88-1.41), or neonatal sepsis (6 studies: odds ratio, 1.13; 95% confidence interval, 0.86-1.49).

CONCLUSION

These data indicate that antenatal corticosteroid administration reduces neonatal mortality in small-for-gestational age infants delivered preterm, with no apparent effect on neonatal morbidity. This supports the use of antenatal corticosteroids to reduce neonatal mortality in pregnancies with small-for-gestational age infants at risk of preterm birth.

Fetal Doppler Assessment in Neonatal Care: Analysis of Fetal Doppler Abnormalities and Neonatal Outcomes

Fetal Doppler ultrasonography provides an effective and noninvasive approach to identify circulatory abnormalities in the maternal-fetal circulation. It is invaluable to assess the hemodynamic status of the fetus under a wide range of physiologic, infectious, and abnormal anatomic conditions. Findings from these studies are often used to make clinical decisions, including whether to proceed with urgent delivery of the fetus. In this review, we focus on key literature describing the main uses of Doppler ultrasonography in neonatal medicine, including how abnormal findings may be implicated in immediate and long-term outcomes. Our review highlights the importance of fetal Doppler examination as an effective intrauterine management strategy, and its full potential is more likely to be realized when considered in context with other available clinical information.

Antenatal Corticosteroids for Reducing Adverse Maternal and Child Outcomes in Special Populations of Women at Risk of Imminent Preterm Birth: A Systematic Review and Meta-Analysis

BACKGROUND

This study synthesizes available evidence on antenatal corticosteroids (ACS) use among special subgroups of women at risk of imminent preterm birth, including those (1) with pregestational and gestational diabetes mellitus, (2) undergoing elective caesarean section (CS) in late preterm (34 to<37 weeks), (3) with chorioamnionitis, and (4) with growth-restricted fetuses.

METHODS

A systematic search of MEDLINE, EMBASE, CINAHL, Cochrane Library, POPLINE, and World Health Organization Regional Databases was conducted for all comparative studies. Two reviewers independently determined study eligibility, extracted data, and assessed study quality. Pooled mean differences and odds ratios with 95% confidence intervals were estimated from available data, based on fixed- and random-effects models, as appropriate.

RESULTS

No eligible studies were identified for ACS use in diabetic pregnant women or those undergoing elective CS at late preterm. Nine studies each on ACS use in women with chorioamnionitis and in women with fetal growth restriction met inclusion criteria; eight studies were separately included in the meta-analyses for the two subpopulations. For ACS administration in women with chorioamnionitis, pooled analyses showed reductions in neonatal mortality (OR: 0.49, 95% CI: 0.34-0.73), respiratory distress syndrome (OR: 0.58, 95% CI: 0.44-0.76), intraventricular haemorrhage (OR: 0.41, 95% CI: 0.24-0.69), and severe intraventricular haemorrhage (OR: 0.40, 95% CI: 0.24-0.69). Maternal and long-term newborn outcomes were not reported. Effects of ACS use were inconclusive for cases with fetal growth restriction.

CONCLUSION

Direct evidence on the effectiveness and safety of ACS is lacking for diabetic pregnant women at risk of preterm birth and those undergoing elective late-preterm CS, though this does not necessarily recommend against their use in diabetic women. While evidence remains inconclusive for women with growth-restricted preterm neonates, ACS appears to benefit preterm neonates delivered by women with chorioamnionitis. High-quality studies on maternal and long-term child outcomes in more diverse settings are needed to establish the balance of potential harms versus benefits in using ACS for these understudied subgroups.

Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments

Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.

Impact of intrauterine growth restriction on preterm lung disease

AIM

Intrauterine growth restriction (IUGR) is an important cause for prematurity and adversely influences prematurity-related morbidities. This study evaluates the impact of IUGR on respiratory outcomes in infants <32 weeks with IUGR and birthweight <10th centile (SGA) compared to matched appropriate for gestation (AGA) controls.

METHODS

The primary outcomes of this retrospective study are short-term pulmonary outcomes of chronic lung disease (CLD), CLD or death, and need for home oxygen at discharge. Subgroup analysis by gestation-based stratification (<28 and ≥28 <32 weeks) was decided a priori.

RESULTS

Total of 153 IUGR and 306 non-IUGR infants were enrolled. The rate of CLD (45% vs. 17%, p = 0.0001), death (16% vs. 4.6%, p = 0.0001), CLD or death (46% vs. 21.5%, p = 0.0001), home oxygen rates (13.7% vs. 6.5%, p = 0.01) and duration of respiratory support was significantly higher in the IUGR group. IUGR emerged as the strongest predictor of CLD (adjusted OR, 95%CI: (8.4 [2, 35]) and CLD or death (12.7 [3, 54]) across all gestation.

CONCLUSION

IUGR is a major risk factor for adverse short-term pulmonary outcomes as reflected by higher rates of CLD, CLD or death, and oxygen dependency at discharge in preterm infants.

Increased lung prolyl hydroxylase and decreased glucocorticoid receptor are related to decreased surfactant protein in the growth-restricted sheep fetus

Experimental placental restriction (PR) by carunclectomy in fetal sheep results in intrauterine growth restriction (IUGR), chronic hypoxemia, increased plasma cortisol, and decreased lung surfactant protein (SP) expression. The mechanisms responsible for decreased SP expression are unknown but may involve decreased glucocorticoid (GC) action or changes in hypoxia signaling. Endometrial caruncles were removed from nonpregnant ewes to induce PR. Lungs were collected from control and PR fetuses at 130-135 (n = 19) and 139-145 (n = 28) days of gestation. qRT-PCR and Western blotting were used to quantify lung mRNA and protein expression, respectively, of molecular regulators and downstream targets of the GC and hypoxia-signaling pathways. We confirmed a decrease in SP-A, -B, and -C, but not SP-D, mRNA expression in PR fetuses at both ages. There was a net downregulation of GC signaling with a reduction in GC receptor (GR)-α and -β protein expression and a decrease in the cofactor, GATA-6. GC-responsive genes including transforming growth factor-β1, IL-1β, and β2-adrenergic receptor were not stimulated. Prolyl hydroxylase domain (PHD)2 mRNA and protein and PHD3 mRNA expression increased with a concomitant increase in hypoxia-inducible factor-1α (HIF-1α) and HIF-1β mRNA expression. There was an increase in mRNA expression of several, but not all, hypoxia-responsive genes. Hence, both GC and hypoxia signaling may contribute to reduced SP expression. Although acute hypoxia normally inactivates PHDs, chronic hypoxemia in the PR fetus increased PHD abundance, which normally prevents HIF signaling. This may represent a mechanism by which chronic hypoxemia contributes to the decrease in SP production in the IUGR fetal lung.

Is it feasible to identify preterm infants with respiratory distress syndrome for early extubation to continuous positive airway pressure post-surfactant treatment during retrieval?

AIM

Preterm infants with respiratory distress syndrome (RDS) requiring surfactant treatment are often retrieved mechanically ventilated to the receiving hospital. INSURE (INtubate, SURfactant, Extubate) technique is not routinely performed by Newborn and Pediatric Emergency Transport Services NSW (NETS) during retrieval. This study aims to evaluate the likelihood of using INSURE technique during retrieval. We attempted to study the clinical characteristics of preterm infants with RDS who were favourably extubated (FE) shortly after admission to the receiving hospital.

METHODS

Retrospective study of preterm infants, gestational age (GA) > 28 weeks with RDS requiring retrieval by NETS.

RESULTS

Two hundred twenty-three infants, median GA of 33 weeks (range 29-36), median birthweight 2200 g (1000-4080) were examined. A percentage of 49.7 received CPAP, and 50.3% required MV. Eighteen (16%) infants were FE (<6 h) at receiving hospital. FiO2 on stabilisation (FiO2 (st)) by NETS correlated with FiO2 on admission to receiving hospital (r = 0.863). A percentage of 81 of ventilated infants received premedications including morphine. No significant differences were noted for GA, stabilisation ventilator settings, surfactant dose (mean 155 mg/kg) and mode of transport between FE and non-FE groups. FiO2 (st) post-surfactant treatment was significantly lower in FE compared with non-FE group (mean 0.28 vs. 0.41 respectively). The area under the curve from receiver operating characteristic based on FiO2 (st) was 0.646 (P = 0.050), the sensitivity and specificity of FiO2 (st) cut-off points (between 0.25 and 0.30) was low.

CONCLUSION

FiO2 on stabilisation post-surfactant treatment has a weak predictive value and may not be adequate to be used as sole criteria to extubate to CPAP prior to transport. FiO2 at stabilisation should be included as an eligibility criteria for a randomised trial of INSURE during retrieval, but other clinical assessments are needed.

The Efficacy of Surfactant Replacement Therapy in the Growth-Restricted Preterm Infant: What is the Evidence?

BACKGROUND

Surfactant replacement therapy (SRT) is an integral part of management of preterm surfactant deficiency respiratory distress syndrome (RDS). Its role in the management of RDS has been extensively studied. However, its efficacy in the management of lung disease in preterm infants born with intrauterine growth restriction (IUGR) has not been systematically studied.

OBJECTIVE

To evaluate the efficacy of exogenous SRT in the management of preterm IUGR lung disease.

METHODS

A systematic search of all available randomized clinical trials (RCT) of SRT in preterm IUGR infants was done according to the standard Cochrane collaboration search strategy. Neonatal respiratory outcomes were compared between the preterm IUGR and appropriately grown for gestational age (AGA) preterm infant populations in eligible studies.

RESULTS

No study was identified which evaluated the efficacy or responsiveness of exogenous SRT in preterm IUGR infants as compared to preterm AGA-infants. The only study identified through the search strategy used small for gestational age (SGA; defined as less than tenth centile for birth weight) as a proxy for IUGR. The RCT evaluated the efficacy or responsiveness of SRT in preterm SGA group as compared to AGA-infants. The rate of intubation, severity of RDS, rate of surfactant administration, pulmonary air leaks, and days on the ventilator did not differ between both groups. However, the requirement for prolonged nasal continuous positive airway pressure (p < 0.001), supplemental oxygen therapy (p < 0.01), and the incidence of bronchopulmonary dysplasia at 28 days and 36 weeks (both p < 0.01) was greater in SGA-infants.

DISCUSSION

There is currently insufficient data available to evaluate the efficacy of SRT in preterm IUGR lung disease. A variety of research strategies will be needed to enhance our understanding of the role and rationale for use of SRT in preterm IUGR lung disease.

Intrauterine growth restriction transiently delays alveolar formation and disrupts retinoic acid receptor expression in the lung of female rat pups

BACKGROUND

We showed that intrauterine growth restriction (IUGR) increases distal airspace wall thickness at birth (postnatal age 0; P0) in rat pups (saccular stage of lung development). However, that report did not assess whether the saccular phenotype persisted postnatally or occurred in males or females, nor did the report identify a potential molecular pathway for the saccular phenotype at P0. We hypothesized that IUGR persistently delays alveolar formation and disrupts retinoic acid receptor (RAR) mRNA and protein levels in the lung of rat pups in a postnatal age- and sex-specific manner.

METHODS

IUGR was induced in pregnant rats by bilateral uterine artery ligation. Alveolar formation and expression of RARα, -β, and -γ were quantified at P0, P6 (alveolar stage), and P21 (postalveolarization).

RESULTS

IUGR increased distal airspace wall thickness in female pups at P0 only. IUGR did not affect male pups at any age. IUGR transiently increased lung RAR-β protein abundance, which inhibits alveolar formation, at P0 in female pups. Serum retinol concentration was normal at all ages.

CONCLUSION

IUGR alone is not sufficient to persistently delay postnatal alveolar formation or disrupt expression of RARs. We speculate that for IUGR to delay alveolar formation postnatally, a second insult is necessary.

Antenatal steroids and the IUGR fetus: are exposure and physiological effects on the lung and cardiovascular system the same as in normally grown fetuses?

Glucocorticoids are administered to pregnant women at risk of preterm labour to promote fetal lung surfactant maturation. Intrauterine growth restriction (IUGR) is associated with an increased risk of preterm labour. Hence, IUGR babies may be exposed to antenatal glucocorticoids. The ability of the placenta or blood brain barrier to remove glucocorticoids from the fetal compartment or the brain is compromised in the IUGR fetus, which may have implications for lung, brain, and heart development. There is conflicting evidence on the effect of exogenous glucocorticoids on surfactant protein expression in different animal models of IUGR. Furthermore, the IUGR fetus undergoes significant cardiovascular adaptations, including altered blood pressure regulation, which is in conflict with glucocorticoid-induced alterations in blood pressure and flow. Hence, antenatal glucocorticoid therapy in the IUGR fetus may compromise regulation of cardiovascular development. The role of cortisol in cardiomyocyte development is not clear with conflicting evidence in different species and models of IUGR. Further studies are required to study the effects of antenatal glucocorticoids on lung, brain, and heart development in the IUGR fetus. Of specific interest are the aetiology of IUGR and the resultant degree, duration, and severity of hypoxemia.

Risk factors for intubation-surfactant-extubation (INSURE) failure and multiple INSURE strategy in preterm infants

The INSURE method, which consists of an intubation-surfactant-extubation sequence, is effective in reducing the need for mechanical ventilation (MV), the duration of respiratory support, and the need for surfactant replacement in preterm infants with respiratory distress syndrome. Although beneficial, the INSURE method fails to avoid MV in selected patients. We demonstrated that body weight <750 g, pO(2)/FiO(2) <218, and a/ApO(2) <0.44 at the first blood gas analysis are independent risk factors for INSURE failure in infants with gestational age <30 weeks. Moreover, we demonstrated that the INSURE treatment can be safely repeated with the aim to avoid MV, since the respiratory outcome did not differ between infants treated with single or multiple INSURE procedures.

Outcomes of small for gestational age micropremies depending on how young or how small they are

Purpose

The outcomes of small for gestational age (SGA) infants especially in extremely low birth weight infants (ELBWIs) are controversial. This study evaluated the mortality and morbidity of ELBWIs, focusing on whether or not they were also SGA.

Methods

The medical records of 415 ELBWIs (birth weight <1,000 g), who were inborn and admitted to the Samsung Medical Center neonatal intensive care unit from January 2000 to December 2008, were reviewed retrospectively. Mortality and morbidities were compared by body size groups: very SGA (VSGA), birth weight ≤3rd percentile; SGA, 3rd to 10th percentile; and appropriate for gestational age (AGA) infants, >10th percentile for gestational age. For gestational subgroup analysis, groups were divided into infants with gestational age ≤24⁺⁶ weeks (subgroup I), 25⁺⁰ to 26⁺⁶ weeks (subgroup II), and ≥27⁺⁰ weeks (subgroup III).

Results

Gestational age was 29⁺²±2⁺⁶ weeks in the VSGA infants (n=49), 27⁺⁵±2⁺² weeks in the SGA infants (n=45), and 25⁺⁴±1⁺⁴ weeks in AGA infants (n=321). Birth weight was 692±186.6 g, 768±132.9 g, and 780±142.5 g in the VSGA, SGA, and AGA groups, respectively. Cesarean section rate and maternal pregnancy-induced hypertension were more common in the VSGA and SGA than in AGA pregnancies. However, chorioamnionitis was more common in the AGA group. The mortalities of the lowest gestational group (subgroup I), and also of the lower gestational group (subgroup I+II) were significantly higher in the VSGA group than the SGA or AGA groups (P=0.020 and P=0.012, respectively). VSGA and SGA infants showed lower incidence in respiratory distress syndrome, ductal ligation, bronchopulmonary dysplasia, intraventricular hemorrhage than AGA group did. However, by multiple logistic regression analysis of each gestational subgroup, the differences were not significant.

Conclusion

Of ELBWIs, extremely SGA in the lower gestational subgroups, had an impact on mortality, which may provide information useful for prenatal counseling.

The INSURE method in preterm infants of less than 30 weeks' gestation

OBJECTIVES

Our aim was to identify the clinical characteristics which could distinguish infants who can be managed with INSURE (intubatio-surfactant-extubation) method for preventing mechanical ventilation (MV) and which could predict INSURE success or failure.

METHODS

Inborn infants with gestational age <30 weeks were Infants were categorised into three groups: (1) infants who needed MV in the delivery room; (2) infants spontaneously breathing who were treated only with NCPAP; (3) infants who were treated with INSURE method.

RESULTS

We studied 125 infants: 30 (24%) required MV, 75 (60%) received INSURE treatment, and 20 (16%) were treated with NCPAP. Sixty-eight (91%) infants were successfully treated with the INSURE method. Infants in the success group had less severe RDS and less occurrence of sepsis and pneumothorax, lower mortality, and shorter duration of stay in the NICU than infants in the failure group. A birth weight <750 g, pO(2)/FiO(2) <218, and a/ApO(2) <0.44 at the first blood gas analysis were independent risk factor for INSURE failure.

CONCLUSIONS

The INSURE method can be applied to the majority of extremely preterm infants and is followed by a high percentage of success.

Subsequent pregnancy outcome after first pregnancy with normotensive early-onset intrauterine growth restriction at <34 weeks of gestation

OBJECTIVE

The aim of this study was to evaluate maternal and fetal outcome of the subsequent pregnancy of primiparous women with a history of early-onset intrauterine growth restriction (IUGR), prompting delivery before 34 weeks of gestation, without concomitant maternal hypertensive disease.

DESIGN

Retrospective cohort study.

SETTING

Tertiary center in the Netherlands.

POPULATION

Women with a normotensive first pregnancy complicated by early-onset severe IUGR, prompting delivery before 34 weeks of gestation.

METHODS

Reproductive follow-up data were recorded for 22 women with a normotensive first pregnancy complicated by early-onset severe IUGR before 34 weeks, referred to the University Medical Centre Utrecht, the Netherlands, between 1993 and 2005.

MAIN OUTCOME MEASURES

Main outcome measures were recurrent IUGR, perinatal mortality, preterm delivery, preeclampsia (PE), pregnancy-induced hypertension, and other major obstetric complications, for example placental abruption.

RESULTS

Mean gestational age at delivery was 29.4 weeks for the index pregnancy compared to 36.4 weeks for the next pregnancy. IUGR recurred in six pregnancies (27.3%). Four subsequent pregnancies were complicated by hypertensive disorders. Perinatal mortality was 72.7% in the index pregnancy, compared to 13.6% in the second pregnancy. Overall, 11 women (54.5%) had an uneventful pregnancy.

CONCLUSION

Women with first pregnancy early-onset IUGR, without concomitant maternal hypertensive disease, frequently develop severe perinatal complications in their subsequent pregnancy.

Intrauterine growth restriction delays surfactant protein maturation in the sheep fetus

Pulmonary surfactant is synthesized by type II alveolar epithelial cells to regulate the surface tension at the air-liquid interface of the air-breathing lung. Developmental maturation of the surfactant system is controlled by many factors including oxygen, glucose, catecholamines, and cortisol. The intrauterine growth-restricted (IUGR) fetus is hypoxemic and hypoglycemic, with elevated plasma catecholamine and cortisol concentrations. The impact of IUGR on surfactant maturation is unclear. Here we investigate the expression of surfactant protein (SP) A, B, and C in lung tissue of fetal sheep at 133 and 141 days of gestation (term 150 +/- 3 days) from control and carunclectomized Merino ewes. Placentally restricted (PR) fetuses had a body weight <2 SD from the mean of control fetuses and a mean gestational Pa(O(2)) <17 mmHg. PR fetuses had reduced absolute, but not relative, lung weight, decreased plasma glucose concentration, and increased plasma cortisol concentration. Lung SP-A, -B, and -C protein and mRNA expression was reduced in PR compared with control fetuses at both ages. SP-B and -C but not SP-A mRNA expression and SP-A but not SP-B or -C protein expression increased with gestational age. Mean gestational Pa(O(2)) was positively correlated with SP-A, -B, and -C protein and SP-B and -C mRNA expression in the younger cohort. SP-A and -B gene expression was inversely related to plasma cortisol concentration. Placental restriction, leading to chronic hypoxemia and hypercortisolemia in the carunclectomy model, results in significant inhibition of surfactant maturation. These data suggest that IUGR fetuses are at significant risk of lung complications, especially if born prematurely.

Effect of weight and age on respiratory complexity in premature neonates

Very low-birth-weight premature infants often suffer from a variety of respiratory problems, including respiratory distress syndrome (RDS), hypopnea and periodic breathing, and apnea. These conditions are likely related to immaturity of the respiratory centers; yet how respiratory rhythms originating from these centers, including their complexity, relate to demographic measures of prematurity remains largely unknown. In 39 neonates with mild RDS (22 males, 28 ± 2 wk gestational age, 1,036 ± 234 g body wt), we derived the univariate association between complexity of two respiratory rhythms [respiratory rate (RR) and tidal volume (Vt)] and postmenstrual age, gestational age, postnatal age, and weight at time of study. RR and Vt rhythm complexities were assessed using approximate entropy, sample entropy, base scale entropy, and forbidden words entropy estimated for 300 consecutive breaths determined from respiratory inductance plethysmography, irrespective of breathing effort rate or amplitude, collected during sleep while the neonates were exposed to nasal continuous positive airway pressure (4–6 cmH2O). RR and Vt exhibited increased complexity with increased maturity, but only in terms of base scale entropy and forbidden words entropy, which are based on pattern matching, rather than approximate entropy and sample entropy, which are based on conditional probabilities. Specifically, RR complexity as measured by forbidden word entropy increased with increasing weight ( r = 0.502), postconceptional age ( r = 0.423), and gestational age ( r = 0.493). As measured by base scale entropy, RR complexity increased with increasing weight ( r = 0.488) and postconceptional age ( r = 0.390). Vt complexity, measured by base scale entropy, was greater with increased postnatal age ( r = 0.428). Our results indicate that respiratory rhythms become more complex with increasing levels of maturity, as indicated by increased weight and several age parameters. This emphasizes the importance of the later weeks of gestation in the maturation of respiratory centers in the brain and suggests a promising use of entropy measures in exploring respiratory maturation in infants.

Lung maturation in small for gestational age fetuses from pregnancies complicated by placental insufficiency or maternal hypertension

BACKGROUND

Clinical studies suggest that respiratory outcome of infants born preterm may be influenced by placental insufficiency and hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. If so, one could expect to see differences in lung maturation indices (lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC)) in the amniotic fluid. The present study investigates lung maturation indices of preterm small for gestational age (SGA) fetuses with or without abnormal Doppler ultrasound examination and with or without maternal hypertension/HELLP syndrome.

STUDY DESIGN

Retrospective cohort study of 76 neonates born in our center between 1997 and 2003 with gestational age (GA) <34 weeks, birth weight <p10 for GA and available results from amniocentesis. All analyses were corrected for potential confounders.

RESULTS

The L/S ratio was significantly higher in the abnormal Doppler group as compared to the normal Doppler group (p=0.02). The L/S ratio was significantly lower in hypertensive pregnancies as compared to normotensive pregnancies (p=0.02). Subdivision of the maternal hypertension group showed a significantly lower L/S ratio in the HELLP syndrome group as compared to the normotension group (p=0.04).

CONCLUSION

The L/S ratio of SGA fetuses is significantly higher in cases with presumed placental insufficiency and significantly lower when pregnancies are complicated by HELLP syndrome. These observations are in line with the hypothesis that placental insufficiency accelerates lung maturation and with recent reports of poorer respiratory outcome in infants from mothers with HELLP syndrome.

Oxidative stress and proinflammatory cytokine levels are increased in premature neonates of preeclamptic mothers with HELLP syndrome

BACKGROUND

Respiratory distress syndrome (RDS) incidence is increased in infants of preeclamptic mothers with hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. RDS and HELLP syndrome have been associated with oxidative stress and inflammatory processes.

OBJECTIVES

We hypothesize that end-tidal carbon monoxide corrected for inhaled CO (ETCOc), malondialdehyde (MDA) (markers of oxidative stress) and proinflammatory cytokine (IL-6, IL-8) production are higher in infants of preeclamptic mothers with HELLP syndrome than in those of preeclamptic mothers without HELLP syndrome.

METHODS

Prospective study of 36 infants of preeclamptic mothers (GA <32 weeks) admitted to the Neonatal Intensive Care Unit. ETCOc was measured at 0-12, 48-72 and 168 h postnatally using the CO-Stattrade mark End-Tidal Breath Analyzer. Simultaneously, blood was sampled for MDA, IL-8 and IL-6.

RESULTS

At 0-12 h, ETCOc, MDA and IL-8 values (median[range]) were significantly higher in HELLP infants than in infants from preeclamptic mothers without HELLP (ETCOc 2.2 [1.5-3.9] vs. 1.8 [0.5-2.9] ppm; MDA 2.3 [1.3-4.1] vs. 1.5 [0.4-3.1] mumol/l; IL-8 145 [24-606] vs. 62 [26-397] pg/ml; all p <0.05). MDA remained significantly higher during the first 168 h of life (2.3 [0.8-5.8] vs. 1.1 [0.8-3.7] mumol/l, p = 0.02).

CONCLUSION

Oxidative stress and proinflammatory cytokine levels are increased in infants of preeclamptic mothers with HELLP syndrome. These processes may cause inactivation of surfactant explaining the increased RDS incidence in these infants.