Meconium aspiration syndrome: from pathophysiology to treatment

Meconium aspiration syndrome (MAS) is a clinical condition characterized by respiratory distress in neonates born through meconium-stained amniotic fluid (MSAF). Despite advances in obstetric practices and perinatal care, MAS remains an important cause of morbidity and mortality in term and post-term newborns. Since the 1960s, there have been significant changes in the perinatal and postnatal management of infants born through MSAF. Routine endotracheal suctioning is no longer recommended in both vigorous and non-vigorous neonates with MSAF. Supportive care along with new treatments such as surfactant, inhaled nitric oxide, and high-frequency ventilation has significantly improved the outcome of MAS patients. However, determining the most appropriate approach for this condition continues to be a topic of debate. This review offers an updated overview of the epidemiology, etiopathogenesis, diagnosis, management, and prognosis of infants with MAS.

Less Invasive Surfactant Administration (LISA) Versus INSURE Method in Preterm Infants: a Retrospective Study

Background

Respiratory distress syndrome (RDS) is a major cause of morbidity and mortality in preterm infants. Early nasal CPAP and selective administration of surfactant via the endotracheal tube are widely used in the treatment of RDS in preterm infants.

Objective

The aim of this study was to compare the need for intubation and mechanical ventilation after surfactant delivery between LISA-treated and INSURE-treated premature infants with respiratory distress syndrome (RDS).

Methods

Retrospective registry-based cohort study enrolled 36 newborns admitted to the neonatal intensive care unit of the "Santa Maria" Hospital of Terni between 2016 and 2023. As a primary outcome, we followed the need for intubation and mechanical ventilation within 72 hours of life, while the secondary outcomes were major neonatal morbidities and death before discharge.

Results

The LISA group and the INSURE group included 13 and 23 newborns respectively. Demographic features showed no significant differences between the two groups. The need for mechanical ventilation in the first 72 hours of life was similar in both groups (p >0.99). There were no significant differences in morbidities.

Conclusion

LISA and INSURE are equally effective modalities for surfactant administration for the treatment of RDS in preterm infants.

Collectins and ficolins in neonatal health and disease

The immune system starts to develop early in embryogenesis. However, at birth it is still immature and associated with high susceptibility to infection. Adaptation to extrauterine conditions requires a balance between colonization with normal flora and protection from pathogens. Infections, oxidative stress and invasive therapeutic procedures may lead to transient organ dysfunction or permanent damage and perhaps even death. Newborns are primarily protected by innate immune mechanisms. Collectins (mannose-binding lectin, collectin-10, collectin-11, collectin-12, surfactant protein A, surfactant protein D) and ficolins (ficolin-1, ficolin-2, ficolin-3) are oligomeric, collagen-related defence lectins, involved in innate immune response. In this review, we discuss the structure, specificity, genetics and role of collectins and ficolins in neonatal health and disease. Their clinical associations (protective or pathogenic influence) depend on a variety of variables, including genetic polymorphisms, gestational age, method of delivery, and maternal/environmental microflora.

Noninvasive Neurally Adjusted Ventilation versus Nasal Continuous or Intermittent Positive Airway Pressure for Preterm Infants: A Systematic Review and Meta-Analysis

The noninvasive neurally adjusted ventilatory assist (NIV-NAVA) is a newly developed noninvasive ventilation technique with promising clinical and ventilatory outcomes for preterm infants. This systematic review and meta-analysis aimed to investigate whether NIV-NAVA has better clinical and ventilatory outcomes than nasal continuous airway pressure (NCPAP) or noninvasive positive pressure ventilation (NIPP) on premature infants. MEDLINE, Embase, and CENTRAL were searched, and randomized controlled trials (RCTs) that compared NIV-NAVA with NCPAP or NIPP for preterm infants (gestational age: <37 weeks) were included. We evaluated the following outcomes in the neonatal intensive care unit: the desaturation rate, failure of noninvasive modality requiring intubation when received as the primary mode or the need for re-intubation after extubation from mechanical ventilation in the secondary mode (weaning), length of stay, and fraction of inspired oxygen. The mean difference and risk ratio were used to represent continuous and dichotomous outcomes, respectively. We included nine RCTs involving 339 preterm infants overall. NIV-NAVA showed similar clinical and ventilatory outcomes to NCPAP or NIPP, except for the maximum diaphragmatic electrical activity. The rate of failure of the noninvasive modality was not statistically different between NIV-NAVA and NCPAP. The pooled estimates for the maximum electrical activity were significantly reduced in NIV-NAVA compared with those in NIPP. The findings suggest that NIV-NAVA may be as safe and effective as NCPAP and NIPP for preterm neonates, particularly those who may not tolerate these alternative noninvasive methods. However, further trials are recommended for greater evidence.

Association of low ficolin-2 concentration in cord serum with respiratory distress syndrome in preterm newborns

Introduction

Ficolin-2 is a serum pattern recognition molecule, involved in complement activation via the lectin pathway. This study aimed to investigate the association of ficolin-2 concentration in cord blood serum with complications related to premature birth.

Methods

546 premature neonates were included. The concentration of ficolin-2 in cord blood serum was determined by a sandwich TRIFMA method. FCN2 genetic variants were analysed with RFLP-PCR, allele-specific PCR, Sanger sequencing or allelic discrimination using TaqMan probes method.

Findings

Cord blood serum ficolin-2 concentration correlated positively with Apgar score and inversely with the length of hospitalisation and stay at Neonatal Intensive Care Unit (NICU). Multivariate logistic regression analysis indicated that low ficolin-2 increased the possibility of respiratory distress syndrome (RDS) diagnosis [OR=2.05, 95% CI (1.24-3.37), p=0.005]. Median ficolin-2 concentration was significantly lower in neonates with RDS than in premature babies without this complication, irrespective of FCN2 gene polymorphisms localised to promoter and 3'untranslated regions: for patients born <33 GA: 1471 ng/ml vs. 2115 ng/ml (p=0.0003), and for patients born ≥33 GA 1610 ng/ml vs. 2081 ng/ml (p=0.012). Ficolin-2 level was also significantly lower in neonates requiring intubation in the delivery room (1461 ng/ml vs. 1938 ng/ml, p=0.023) and inversely correlated weakly with the duration of respiratory support (R=-0.154, p<0.001). Interestingly, in the neonates born at GA <33, ficolin-2 concentration permitted differentiation of those with/without RDS [AUC=0.712, 95% CI (0.612-0.817), p<0.001] and effective separation of babies with mild RDS from those with moderate/severe form of the disease [AUC=0.807, 95% CI (0.644-0.97), p=0.0002].

Conclusion

Low cord serum ficolin-2 concentration (especially in neonates born at GA <33 weeks) is associated with a higher risk of developing moderate/severe RDS, requiring respiratory support and intensive care.

Association between Thyroid Function and Respiratory Distress Syndrome in Preterm Infants

Thyroid hormones are known to influence the production and secretion of pulmonary surfactant. The objective of this study was to explore the relationship between respiratory distress syndrome (RDS) and thyroid hormones. This was a retrospective study of preterm infants at 24−33 weeks gestational age from April 2017 to February 2019. T3, free T4 (fT4), and thyroid-stimulating hormone (TSH) were measured 1, 3, and 6 weeks after birth. Multivariate logistic regression analyses were performed to determine the relationship between RDS and TSH. A total of 146 infants were enrolled. Of these, 60 had RDS, 72 had no RDS, and 14 were excluded. T3 and TSH were lower in the RDS groups (p < 0.05) on the day of birth. Multivariate logistic regression analysis indicated that lower serum TSH levels immediately after birth were associated with a higher incidence of RDS (OR, 0.89; 95% CI, 0.81−0.97). The TSH level was associated with the incidence of RDS. This suggests that suppression of the hypothalamus−pituitary axis function contributes to RDS, which is the result of surfactant deficiency.

Role of lung ultrasound in diagnosing and differentiating transient tachypnea of the newborn and respiratory distress syndrome in preterm neonates

Aim

To evaluate the accuracy of lung ultrasound in diagnosing and differentiating transient tachypnea of the newborn and respiratory distress syndrome in preterm neonates.

Material and methods

This was a single-center study. From January 2020 to June 2021. A total of 100 preterm neonates, admitted to the neonatal intensive care unit with symptoms of respiratory distress within six hours of birth, including 50 diagnosed with transient tachypnea of the newborn and 50 with respiratory distress syndrome on the basis of clinical examination, laboratory testing, chest X-rays, were recruited in the study. Lung ultrasound was performed in each neonate by a senior radiologist who was blinded to the clinical diagnosis. Lung ultrasound findings in both conditions were analyzed and compared.

Results

Pulmonary edema manifesting as alveolar-interstitial syndrome, double lung point sign and less commonly as white out lungs in the absence of consolidation has 100% sensitivity and specificity in diagnosing transient tachypnea of the newborn. A combination of three signs of consolidation with air or fluid bronchograms, white out lungs and absent spared areas has 100% sensitivity and specificity for diagnosing respiratory distress syndrome. Double lung point sign was seen only in infants suffering from transient tachypnea of the newborn and consolidation with air or fluid bronchograms only in cases of respiratory distress syndrome.

Conclusion

Lung ultrasound can accurately diagnose and reliably differentiate transient tachypnea of the newborn and respiratory distress syndrome in preterm neonates. It has advantages that cannot be replicated by chest radiography. Lung ultrasound may be used as an initial screening tool.

Lung ultrasound to guide the administration of exogenous pulmonary surfactant in respiratory distress syndrome of newborn infants: A retrospective investigation study

BACKGROUND

Respiratory distress syndrome (RDS) is a common disease that seriously endangers the life and safety of newborns, especially premature infants. Exogenous pulmonary surfactant (PS) is the specific agent for the treatment of neonatal RDS. Lung ultrasound (LUS) has been successfully used in the diagnosis of RDS, but its value in guiding the application of PS is still unclear. This paper explored whether the application of PS under LUS monitoring has some advantages, including (1) decreasing the misdiagnosis rate of RDS and decreasing probability of using PS, and (2) reducing the dose of PS without reducing the therapeutic effect.

METHODS

This study included two parts. Part 1: To decide whether the LUS is good to differentiate RDS from other lung diseases in the premature infants. All patients who were diagnosed with RDS and required PS treatment based on conventional criteria were routinely examined by LUS. Then, according to LUS findings, we decided whether they needed to receive PS treatment. Part 2: To see the dose reduction of surfactant is applicable. In RDS patients diagnosed based on LUS presentation and treated with Curosurf (Chiesi Pharmaceutical, Parma, Italy), the dose of Curosurf was compared with that recommended by the European RDS management guidelines.

RESULTS

(1) Since March 2017, 385 newborn infants admitted to our neonatal intensive care unit met the traditional diagnostic criteria of RDS. Of these, only 269 cases were diagnosed with RDS and needed PS treatment according to LUS manifestations. The other 116 infants who did not meet the criteria for ultrasound diagnosis of RDS did not receive PS supplementation but obtained good outcomes, that is LUS findings decreased a misdiagnosis rate of RDS by 30.1% and subsequently resulted in a 30.1% reduction in PS use. (2) Among the 269 RDS patients diagnosed based on LUS findings, 148 were treated with Curosurf (another 121 RDS infants who received domestic PS treatment were not included in the study group), and the average dose was 105.4 ± 24.3 mg/kg per time, which is significantly lower than the dose of 200 mg/kg per time recommended by the European RDS guidelines. (3) The mortality rate of RDS patients was 0%, and no patients had ventilator-associated pneumonia or bronchopulmonary dysplasia in this study.

CONCLUSION

LUS can decrease the misdiagnosis rate of RDS, thereby decreasing the probability of using PS and decreasing the dose of PS, and can help RDS infants to achieve better outcomes.

Respiratory distress syndrome management in resource limited settings-Current evidence and opportunities in 2022

The complications of prematurity are the leading cause of neonatal mortality worldwide, with the highest burden in the low- and middle-income countries of South Asia and Sub-Saharan Africa. A major driver of this prematurity-related neonatal mortality is respiratory distress syndrome due to immature lungs and surfactant deficiency. The World Health Organization's Every Newborn Action Plan target is for 80% of districts to have resources available to care for small and sick newborns, including premature infants with respiratory distress syndrome. Evidence-based interventions for respiratory distress syndrome management exist for the peripartum, delivery and neonatal intensive care period- however, cost, resources, and infrastructure limit their availability in low- and middle-income countries. Existing research and implementation gaps include the safe use of antenatal corticosteroid in non-tertiary settings, establishing emergency transportation services from low to high level care facilities, optimized delivery room resuscitation, provision of affordable caffeine and surfactant as well as implementing non-traditional methods of surfactant administration. There is also a need to optimize affordable continuous positive airway pressure devices able to blend oxygen, provide humidity and deliver reliable pressure. If the high prematurity-related neonatal mortality experienced in low- and middle-income countries is to be mitigated, a concerted effort by researchers, implementers and policy developers is required to address these key modalities.

Antenatal corticosteroids and short-term neonatal outcomes in term and near-term infants of diabetic mothers. Analysis of the Qatar PEARL-peristat registry

OBJECTIVES

A recent discussion surrounding the extension of antenatal corticosteroid (ACS) use beyond 34 weeks of gestation did not include the subgroup of infants of diabetic mothers (IDM). We aimed to examine the association between ACS exposure and outcomes in neonates born at term and at near-term gestation in a large cohort of IDMs.

METHODS

We selected 13976 eligible near-term and term infants who were included in the PEARL-Peristat Perinatal Registry Study (PPS). We assessed the association of ACS exposure with neonatal outcomes in a multivariate regression model that controlled for diabetes mellitus (DM) and other perinatal variables.

RESULTS

The incidence of DM was 28% (3,895 of 13,976) in the cohort. Caesarean section was performed in one-third of the study population. The incidence of ACS exposure was low (1.8%) and typically occurred>2 weeks before delivery. The incidence rates of respiratory distress syndrome (RDS)/ transient tachypnoea of newborns (TTN), all-cause neonatal intensive care unit (NICU) admissions, NICU admissions for hypoglycaemia, and low 5-min Apgar scores were 3.5, 8.8, 1.3, and 0.1%, respectively. In a multivariate regression model, ACS was associated with a slight increase in NICU admissions (OR: 1.44; 95% CI: 1.04-2.03; p=0.028), but not with RDS/TTN.

CONCLUSIONS

Although the low exposure rate was a limitation, ACS administration did not reduce respiratory morbidity in near-term or term IDMs. It was independently associated with an increase in NICU admissions. Randomized controlled trials are required to assess the efficacy and safety of ACS administration in diabetic mothers at late gestation.

ABCA3 gene mutations shape the clinical profiles of severe unexplained respiratory distress syndrome in late preterm and term infants

BACKGROUND

The majority of unexplained respiratory distress syndrome (URDS) cases in late preterm and term infants are caused by genetic abnormalities, with the most common of these being ABCA3 gene mutation. At present, it is unclear to neonatologists whether URDS patients with ABCA3 mutation have similar or more challenging clinical profiles to those without any defined genetic abnormalities. Our study aimed to answer this question by comparing the clinical characteristics of severe URDS patients with homozygous or compound heterozygous ABCA3 mutations, a single ABCA3 mutation, or no defined genetic abnormalities.

METHODS

This retrospective cohort study involved 39 late preterm and term infants with URDS underwent a clinical exome sequencing at a tertiary neonatal intensive care unit between January 2013 and December 2019. Based on the sequencing result, the study subjects were classified into the homozygous or compound heterozygous mutations, single ABCA3 mutation, or no defined genetic abnormalities groups. The major outcomes, including mortality, the age of symptom onset and development of severe RDS, and the radiological score, were compared between the groups.

RESULTS

A novel splicing site (c.3862+1G>C) was identified in one twin with homozygous expression. Patients with homozygous or compound heterozygous ABCA3 mutations exhibited symptom onset and development of severe respiratory distress syndrome (RDS) earlier than those with a single mutation or no genetic abnormalities (P<0.05). These patients also had higher mortality rates than those without genetic abnormalities (P=0.029). The total radiological scores were 51.14±4.91, 44.20±6.54, 35.91±4.42 for patients with homozygous or compound heterozygous mutations, a single mutation, and a wild-type gene, respectively, with significant differences between the groups observed by pairwise comparison (all P<0.05).

CONCLUSIONS

Late preterm or term infants with URDS due to homozygous or compound heterozygous ABCA3 mutations exhibited more challenging clinical profiles than those without genetic abnormalities. However, whether this relationship exists between patients with a single ABCA3 mutation and those without genetic abnormalities warrants further study.

Electrical impedance tomography reveals pathophysiology of neonatal pneumothorax during NAVA

Pneumothorax is a potentially life-threatening complication of neonatal respiratory distress syndrome (RDS). We describe a case of a tension pneumothorax that occurred during neurally adjusted ventilatory assist (NAVA) in a preterm infant suffering from RDS. The infant was included in a multicenter study examining the role of electrical impedance tomography (EIT) in intensive care and therefore continuously monitored with this imaging method. The attending physicians were blinded for EIT findings but offline analysis revealed the potential of EIT to clarify the underlying cause of this complication, which in this case was heterogeneous lung disease resulting in uneven ventilation distribution. Instantaneous increase in end-expiratory lung impedance on the affected side was observed at time of the air leak. Real-time bedside availability of EIT data could have modified the treatment decisions made.

Functional characterization of four ATP-binding cassette transporter A3 gene (ABCA3) variants

ABCA3 transports phospholipids across lamellar body membranes in pulmonary alveolar type II cells and is required for surfactant assembly. Rare, biallelic, pathogenic ABCA3 variants result in lethal neonatal respiratory distress syndrome and childhood interstitial lung disease. Qualitative functional characterization of ABCA3 missense variants suggests two pathogenic classes: disrupted intracellular trafficking (type I mutant) or impaired ATPase-mediated phospholipid transport into the lamellar bodies (type II mutant). We qualitatively compared wild-type (WT-ABCA3) with four uncharacterized ABCA3 variants (c.418A>C;p.Asn140His, c.3609_3611delCTT;p.Phe1203del, c.3784A>G;p.Ser1262Gly, and c.4195G>A;p.Val1399Met) in A549 cells using protein processing, colocalization with intracellular organelles, lamellar body ultrastructure, and ATPase activity. We quantitatively measured lamellar body-like vesicle diameter and intracellular ABCA3 trafficking using fluorescence-based colocalization. Three ABCA3 variants (p.Asn140His, p.Ser1262Gly, and p.Val1399Met) were processed and trafficked normally and demonstrated well-organized lamellar body-like vesicles, but had reduced ATPase activity consistent with type II mutants. P.Phe1203del was processed normally, had reduced ATPase activity, and well-organized lamellar body-like vesicles, but quantitatively colocalized with both endoplasmic reticulum and lysosomal markers, an intermediate phenotype suggesting disruption of both intracellular trafficking and phospholipid transport. All ABCA3 mutants demonstrated mean vesicle diameters smaller than WT-ABCA3. Qualitative and quantitative functional characterization of ABCA3 variants informs mechanisms of pathogenicity.

Study on the Relationship Between Respiratory Distress Syndrome and SP-A1 (rs1059057) Gene Polymorphism in Mongolian Very Premature Infants

Aim: To study the relationship between rs1059057 polymorphism of pulmonary surfactant protein A1 (SP-A1) and respiratory distress syndrome (RDS) in Mongolian very premature infants. Methods: Applying the strategy of case-control study, 120 Mongolian RDS very premature infants (58 males and 62 females) in the western part of Inner Mongolia were selected as the case group, and 120 subjects of non-RDS very premature infants (56 males and 64 females) with the same nationality, same sex and similar gestational age were used as the control group. The single nucleotide polymorphism (SNP) site rs1059057 of SP-A1 was genotyped using polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). Results: Two genotypes, A/G and A/A, were detected at the SP-A1 rs1059057 locus in the western part of Inner Mongolia. In the case group, the frequencies of two genotypes were 53 and 47%, and the frequencies of A allele and G allele were 73 and 27%, respectively. In the control group, the frequencies of the two genotypes were 42 and 58%, and the frequencies of A allele and G allele were 79 and 21%, respectively. There was no significant difference in the genotype frequency of SP-A1 (rs1059057) locus between the case group and the control group (X 2 = 3.275, P > 0.05), and no significant difference in allele frequency between the case group and the control group (X 2 = 2.255, P > 0.05). Conclusion: The genotypes and allele frequencies of SP-A1 (rs1059057) locus were not associated with the incidence of RDS in Mongolian very premature infants in western Inner Mongolia.

Non-invasive high flow oscillatory ventilation in comparison with nasal continuous positive pressure ventilation for respiratory distress syndrome, a literature review

BACKGROUND

Noninvasive high-frequency oscillatory ventilation (NHFOV) keeps the lung open with add-on effective rhythmic oscillations in addition to allowing spontaneous breathing. This review aims at reconstructing the different pieces of available research articles and evidence into a more solid collective evidence for NHFOV in preterm infants with respiratory distress syndrome (RDS).

METHODS

A thorough systemic search was conducted in Medline, Embase, Web of Science, Google Scholar, CINAHL, and Cochrane. Randomized controlled trials (RCTs) on preterm infants with RDS comparing NHFOV with nasal continuous positive airway pressure (NCPAP) in terms of PCO₂ change, need for ventilation, duration of respiratory support, mortality air leak, or BPD were included. Data quality assessment and meta-analyses were carried out.

RESULTS

Five RCTs involving 270 preterm infants included in the review. PCO₂ relatively decreased on NHFOV (MD = 3.84, confidence interval (CI) 7.32-0.35, p = .03). On the other hand, relative risk (RR) of intubation was unquestionably decreased with NHFOV in comparison with NCPAP (RR  =  0.43, CI 0.25-0.75, p = .003) without statistical heterogeneity I² = 0%. Although the risk of mortality was less in NHFOV, the difference was statistically insignificant (RR = 0.72, CI 0.24-2.18, p = .56). Other outcomes reported in single studies only. Duration of respiratory support was significantly shorter in NHFOV compared with NCPAP (37.35 ± 8.96 versus 49.77 ± 10.33, p = .009), whereas air leak and BPD were reported in very few cases without a significant difference between the two interventions.

CONCLUSIONS

NHFOV improved the PCO₂ elimination and decreased the risk of intubation without a significant change in mortality compared with NCPAP.

Fine Tuning Non-invasive Respiratory Support to Prevent Lung Injury in the Extremely Premature Infant

Within the last decades, therapeutic advances, such as antenatal corticosteroids, surfactant replacement, monitored administration of supplemental oxygen, and sophisticated ventilatory support have significantly improved the survival of extremely premature infants. In contrast, the incidence of some neonatal morbidities has not declined. Rates of bronchopulmonary dysplasia (BPD) remain high and have prompted neonatologists to seek effective strategies of non-invasive respiratory support in high risk infants in order to avoid harmful effects associated with invasive mechanical ventilation. There has been a stepwise replacement of invasive mechanical ventilation by early continuous positive airway pressure (CPAP) as the preferred strategy for initial stabilization and for early respiratory support of the premature infant and management of respiratory distress syndrome. However, the vast majority of high risk babies are mechanically ventilated at least once during their NICU stay. Adjunctive therapies aiming at the prevention of CPAP failure and the support of functional residual capacity have been introduced into clinical practice, including alternative techniques of administering surfactant as well as non-invasive ventilation approaches. In contrast, the strategy of applying sustained lung inflations in the delivery room has recently been abandoned due to evidence of higher rates of death within the first 48 h of life.

Comparison between two doses of betamethasone administration with 12 hours vs. 24 hours intervals on prevention of respiratory distress syndrome: a randomised trial

The purpose of the present study was to compare the effect of a two-dose administration of betamethasone with 12 hours interval vs. 24 hours interval on neonatal respiratory distress syndrome (RDS). The study was performed as a randomised clinical trial on 201 pregnant women with a gestational age of 26-34 weeks. In one group 12 mg of betamethasone every 12 hours for two doses and in the other group 12 mg of betamethasone every 24 hours for two doses were prescribed intramuscularly. There were no significant differences between the two groups according to maternal age, parity, gravidity, BMI, neonatal sex, need to surfactant, NICU admission, NICU stay, neonatal death, neonatal sepsis and Apgar score at minutes 1 and 5, but the gestational age at the beginning of the study and delivery receiving complete course of betamethasone and neonatal weight were lower in 24 hours group. RDS, necrotising enterocolitis, intra-ventricular haemorrhage and chorioamnionitis were more in the 24 hours' group. Multiple regression analysis showed that RDS and IVH (p = .022, RR = 0.07, CI95% 0.006-0.96 and p = .013; RR = 0.9, CI95% 0.1-0.89, respectively) were more in the 24 hours group and neonatal death (p = .034, RR = 4.7, CI95% 1.07-16.2) and NEC (p = 0.038, RR = 2.5, CI95% 1.7-3.7), were more in the 12 hours group. In conclusion, it seems that 12 hours interval betamethasone therapy may be considered as an alternative treatment in the case of preterm labour for acceleration of lung maturity; however, it is suggested that more studies should be performed on this issue and various morbidities. IMPACT STATEMENT What is already known on this subject: Administration of a single course of corticosteroids in all women with a gestational age of 24-34 weeks of pregnancy who are at risk for preterm labour and delivery has been recommended. The accepted regimen by National Institutes of Health (NIH) is an injection of betamethasone for two doses with 24 hours interval. What do the results of this study add: Twelve hours interval betamethasone therapy may be considered as an alternative treatment in the cases of preterm labour for acceleration of lung maturity. What are the implications of these findings for clinical practice and/or further research: Prescription of two doses (complete regimen) is more important than the interval between two doses for obtaining the maximum effect in a preterm birth.