European Journal of Cardiovascular Medicine

Antenatal corticosteroids (ACS) have become one of the most important interventions in modern obstetrics for the prevention of neonatal morbidity and mortality associated with preterm birth. The earliest evidence was consolidated by the NIH Consensus Panel (1994, 1995), which formally recommended ACS for women at risk of preterm delivery, highlighting significant reductions in respiratory distress syndrome (RDS), intraventricular haemorrhage (IVH), and neonatal mortality [1,2].

Meta-analyses have since reinforced these findings. Crowley (1995) demonstrated across multiple randomised trials that antenatal corticosteroid therapy markedly reduces adverse neonatal outcomes without significant maternal risk [3]. Similarly, the Cochrane Review by Roberts and Dalziel (2006) confirmed that corticosteroid administration before preterm birth accelerates fetal lung maturation and improves survival, with benefits extending to prevention of necrotising enterocolitis and systemic infections [4].

While these benefits are well established for early preterm gestations, questions remain regarding their role in late-preterm (34–36 weeks) deliveries. Several studies have shown that neonates born at late-preterm gestations still face increased risks of respiratory morbidity compared with term counterparts [5]. For example, Yoder et al. (2008) reported higher rates of respiratory complications despite changes in obstetric practice [15], while the Consortium on Safe Labor (2010) demonstrated a significantly higher burden of respiratory morbidity in this group [16]. Furthermore, the NICHD workshop summary (Raju et al., 2006) highlighted the need for optimising care in late-preterm infants, given their disproportionate contribution to neonatal morbidity [17].

Given these controversies, further evaluation of the role of ACS, particularly in different population settings, remains crucial. The present study was conducted to assess the maternal and neonatal outcomes following antenatal corticosteroid administration in women at risk of preterm birth in a tertiary hospital setting.

Aim

The primary aim of this study was to assess the effectiveness of antenatal corticosteroid administration on neonatal outcomes in women at risk of late preterm delivery.

General Objective

To evaluate the impact of a complete course of antenatal corticosteroids, administered to mothers at risk of late preterm birth, on maternal and neonatal morbidity and mortality.

Specific Objectives

1. To identify maternal and obstetric risk factors associated with late preterm deliveries.
2. To assess the efficacy of dexamethasone in improving neonatal outcomes in late preterm births compared with no corticosteroid exposure.

To compare the incidence of adverse neonatal outcomes potentially attributable to dexamethasone in late preterm births, relative to counterparts not receiving corticosteroids

Study Design and Setting

This was a prospective, longitudinal, single-centre comparative observational study conducted at the Department of Gynaecology and Obstetrics, Nil Ratan Sircar Medical College & Hospital, Kolkata, over a period of 12 months from April 2021 to March 2022. The aim was to evaluate the effect of antenatal corticosteroid administration on neonatal outcomes in women at risk of late preterm delivery (between 34 weeks 0 days and 36 weeks 6 days of gestation).

Study Population

Pregnant women with singleton pregnancies who were at high risk of delivery in the late preterm period and who presented either in the outpatient or inpatient departments during the study period were considered for inclusion.

Inclusion Criteria

• Singleton pregnancy with gestational age between 34+0 and 36+6 weeks, confirmed by early ultrasound.
• High probability of delivery in the late preterm period, defined by any of the following:
• Spontaneous rupture of membranes (PROM)
• Preterm labour with:
• ≤4 uterine contractions in 20 minutes or ≤8 in 60 minutes
• Cervical dilatation ≤3 cm with ≥75% effacement
• Planned delivery (induction or caesarean) expected between 36 hours and 7 days of admission.

Exclusion Criteria

• Prior corticosteroid use during current pregnancy
• Multifetal pregnancy (including twins reduced to singleton after 14 weeks)
• Known fetal anomalies, fetal demise, or hydrops
• Maternal contraindications to corticosteroids (e.g., hypersensitivity, fungal infection, immunocompromised state)
• Pre-existing diabetes
• Imminent delivery within 12 hours (e.g., active labour with cervical dilation >8 cm or non-reassuring fetal status)
• Participation in other interventional trials

Grouping and Intervention

A total of 120 eligible participants were enrolled and divided into two groups based on hospital registration number:

• Group 1 (Steroid Group, n=60): Received antenatal corticosteroids – 6 mg intramuscular dexamethasone, four doses 12 hours apart.
• Group 2 (Control Group, n=60): Did not receive corticosteroids.

Data Collection

Baseline maternal demographics and clinical data were recorded at admission, including:

• Age, parity, BMI
• History of previous preterm birth or abortion
• History of pregnancy-induced hypertension (PIH), stress, or addiction
• General and obstetric examination findings

All patients were followed through delivery and postnatally until discharge. Data were collected on both maternal and neonatal outcomes.

Neonatal Parameters Assessed

• Need for immediate resuscitation at birth
• Requirement for respiratory support (nasal oxygen, CPAP, or mechanical ventilation)
• Surfactant administration
• APGAR score at 1 and 5 minutes
• NICU admission
• Occurrence of sepsis
• Neonatal hypoglycemia

Maternal Outcomes Assessed

• Occurrence of chorioamnionitis or any corticosteroid-related adverse event

Ethical Considerations

The study protocol was reviewed and approved by the Institutional Ethics Committee of NRSMCH. Informed written consent was obtained from all participants before enrollment.

Statistical Analysis

Data were entered and analyzed using SPSS version24. Continuous variables were expressed as mean ± standard deviation and compared using the Student's t-test. Categorical variables were expressed as frequencies and percentages and analyzed using the Chi-square test or Fisher’s exact test where appropriate. A p-value <0.05 was considered statistically significant.

Sample size was calculated based on expected differences in respiratory morbidity between groups, accounting for a 10% attrition rate, resulting in 60 subjects per group (total n = 120).

Baseline Characteristics

A total of 120 pregnant women were enrolled in the study and equally allocated into two groups: 60 participants received antenatal corticosteroids (Group 1) and 60 did not (Group 2). Baseline maternal characteristics including age, parity, BMI, and obstetric history were comparable between the two groups, with no statistically significant differences in key variables such as mean age, parity, prior preterm birth, or hypertensive disorders.

The mean maternal age was slightly higher in Group 1 (26.5 ± 5.19 years) compared to Group 2 (24.08 ± 4.03 years), although the difference was not statistically significant (p = 0.522). Distribution across age subgroups was also similar. The parity distribution indicated a slightly higher proportion of nulliparous women in the steroid group (43.3%) compared to the control group (13.3%). The BMI distribution revealed that a majority of women in both groups had a normal BMI (18.5–24.9), with underweight status (BMI <18.5) being more common in Group 2 (26.7%) than Group 1 (21.7%).

Additionally, previous history of preterm birth, pregnancy-induced hypertension (PIH), and stress or addiction did not differ significantly between the two groups. These findings suggest appropriate group matching and comparability at baseline.

Table 1. Baseline Characteristics of Study Groups

Note: Dash (–) indicates no statistical comparison was reported for subcategories. Significance threshold set at p < 0.05.

Figure 1. Comparison of Baseline Maternal Characteristics Between Study Groups

Bar chart illustrating the distribution of selected maternal characteristics in the corticosteroid (Group 1) and non-steroid (Group 2) groups, including parity, BMI categories, and clinical history such as preterm birth, pregnancy-induced hypertension (PIH), and stress/addiction. The two groups were largely comparable at baseline.

2.Neonatal Outcomes

The administration of antenatal corticosteroids was associated with several notable differences in neonatal outcomes between the two study groups.

As shown in Table 2, neonates in the corticosteroid group demonstrated a statistically significant reduction in both the requirement for respiratory support (11.7% vs. 18.3%, p = 0.0022) and the rate of NICU admissions (11.7% vs. 20.0%, p = 0.018) when compared to the non-steroid group. These findings underscore the beneficial effect of corticosteroids in improving immediate neonatal respiratory adaptation in the late preterm period.

Conversely, the incidence of neonatal hypoglycemia was significantly higher among neonates exposed to corticosteroids (23.3% vs. 15.0%, p = 0.0048), indicating an important potential side effect requiring clinical monitoring.

No statistically significant differences were observed between the groups in terms of immediate resuscitation, surfactant use, neonatal sepsis, APGAR score, or maternal chorioamnionitis.

Table 2. Neonatal Outcomes in the Two Study Groups

Note: *p < 0.05 considered statistically significant.

Figure 2. Comparison of Statistically Significant Neonatal Outcomes

Comparison of neonatal outcomes showing statistically significant differences between the corticosteroid and non-steroid groups. Respiratory support and NICU admission were significantly reduced in the steroid group, while neonatal hypoglycemia was significantly more frequent.

3.Maternal Outcomes

In addition to evaluating neonatal parameters, the study also assessed maternal morbidity associated with corticosteroid administration during the late preterm period.

Mode of Delivery

The distribution of delivery mode was similar across both groups. In the corticosteroid group (Group 1), the rate of vaginal delivery was 65.0% (n = 39), while caesarean delivery accounted for 35.0% (n = 21). In the non-steroid group (Group 2), 60.0% (n = 36) delivered vaginally, and 40.0% (n = 24) underwent caesarean section. The difference in delivery mode was not statistically significant (p = 0.558), indicating that antenatal corticosteroid administration did not influence the likelihood of caesarean delivery.

Chorioamnionitis

The incidence of maternal infection (clinical chorioamnionitis) was low and comparable between the two groups. Chorioamnionitis was reported in 11.6% (n = 7) of patients in Group 1 and 10.0% (n = 6) in Group 2 (p = 0.414). This suggests that antenatal corticosteroid exposure was not associated with an increased risk of intrauterine infection during the late preterm period.

Pregnancy-Induced Hypertension (PIH)

A history of PIH was observed in 11.7% (n = 7) of participants in Group 1 and 20.0% (n = 12) in Group 2. Although more common in the control group, the difference did not reach statistical significance (p = 0.428).

Adverse Effects of Corticosteroids

No acute adverse maternal effects attributable to corticosteroid administration (e.g., severe hyperglycemia, systemic reactions) were reported during the study period. Maternal blood glucose levels were monitored, and no significant steroid-related complications were recorded.

These findings indicate that the administration of a complete course of antenatal corticosteroids in women at risk of late preterm delivery is not associated with increased maternal morbidity, including infection or hypertensive complications. Additionally, the intervention did not affect the mode of delivery or result in observable adverse drug reactions.

Table 3. Maternal Outcomes in the Two Study Groups

Note: PIH – Pregnancy-Induced Hypertension; N/A – Not Applicable; Dash (–) indicates not applicable or no statistical test performed.

Figure 3. Maternal Outcomes in Corticosteroid and Non-Steroid Groups

Maternal outcome comparison between the two groups, showing similar distributions in vaginal/caesarean deliveries, rates of chorioamnionitis, and history of PIH. Corticosteroid administration was not associated with increased maternal complications.

In this prospective observational study, we investigated the effects of antenatal corticosteroid administration in women at risk of late preterm delivery (34⁰–36⁶ weeks) on neonatal and maternal outcomes. Our findings contribute to the evolving evidence on optimizing perinatal care in this vulnerable gestational window.

The incidence of respiratory support in neonates was significantly reduced in the corticosteroid group (11.7%) compared to the non-steroid group (18.3%, p = 0.0022). This is consistent with the findings of Hibbard et al. (2010), who demonstrated in a large cohort that late preterm infants had a higher risk of respiratory morbidity compared to term infants, supporting the role of antenatal corticosteroids in mitigating this risk [9]. Similarly, Porto et al. (2011) reported a 44% reduction in respiratory complications following corticosteroid administration in late preterm infants, reinforcing the benefit of a complete steroid course [10].

In our study, NICU admissions were significantly lower in the steroid-exposed group (11.7% vs. 20.0%, p = 0.018). This aligns with the randomized trial by Stutchfield et al. (2005), which found that antenatal betamethasone reduced neonatal unit admissions after elective cesarean section at term, likely by improving pulmonary maturity [11]. Although their population differed slightly, the underlying mechanism—enhanced fetal lung development—remains consistent.

A key adverse effect noted in our study was a significantly higher rate of neonatal hypoglycemia in the steroid group (23.3% vs. 15.0%, p = 0.0048). Raju et al. (2006) summarized that late preterm infants have immature glucose regulation, and corticosteroids may transiently exacerbate this susceptibility by increasing insulin sensitivity [12]. This highlights the need for postnatal glucose monitoring in neonates exposed to antenatal steroids.

Contrary to some reports, we did not observe a significant reduction in the need for neonatal resuscitation or surfactant therapy. In our study, resuscitation was needed in 15.0% of neonates in the steroid group versus 23.3% in the control group (p = 0.318), while surfactant use remained low and comparable (1.7% vs. 5.0%). A study by Balci et al. (2010) noted decreased surfactant use in steroid-exposed late preterm infants, although their findings did not reach statistical significance either [13].

We also evaluated the APGAR scores, where a lower score (<7) was observed in 11.7% of the steroid group vs. 21.7% in controls (p = 0.428). While the difference was not statistically significant, this trend mirrors the findings of Liggins and Howie (1972), who were the first to demonstrate improved neonatal vitality scores after antenatal glucocorticoids in preterm infants [14].

Our data showed no significant difference in the incidence of neonatal sepsis (8.3% in both groups). This is in line with the meta-analysis by the NICHD workshop summarized by Raju et al. (2006), which reported no consistent evidence of increased neonatal infection risk following corticosteroid exposure [12].

On the maternal side, chorioamnionitis occurred in 11.6% of the steroid group and 10.0% in the control group (p = 0.414), showing no significant increase in infection risk. Martin et al. (2015) also reported similar safety outcomes for corticosteroids during the late preterm period [13].

Importantly, no acute steroid-related adverse effects were reported among mothers in our cohort. This supports the safety profile documented by Chan and Zhang (1999), who reviewed corticosteroid use in late preterm trials and found no increase in maternal morbidity when properly monitored [15].

Lastly, mode of delivery was not influenced by steroid use in our study, with caesarean delivery rates of 35.0% in Group 1 vs. 40.0% in Group 2 (p = 0.558). This neutrality is expected, as steroids primarily aim to reduce neonatal morbidity rather than influence obstetric decision-making directly.

Limitations

This study has several limitations that should be acknowledged. First, it was conducted at a single tertiary care centre with a relatively modest sample size, which may limit the generalizability of the findings to broader populations. Second, although efforts were made to ensure comparable baseline characteristics between groups, residual confounding cannot be fully excluded due to the observational design. Third, the study primarily evaluated short-term neonatal and maternal outcomes; therefore, the potential long-term effects of antenatal corticosteroid exposure, such as growth, neurodevelopment, or metabolic sequelae, could not be assessed. Finally, glucose monitoring protocols varied slightly between participants, which may have influenced the detection rates of neonatal hypoglycemia. These limitations highlight the need for larger, multicentric randomized controlled trials with extended follow-up to validate and expand upon our results

The administration of a complete course of antenatal corticosteroids in women at risk of late preterm delivery was associated with a significant reduction in neonatal respiratory morbidity and NICU admissions, thereby supporting its role in improving perinatal outcomes in this gestational age group. However, the intervention was also linked to a higher incidence of neonatal hypoglycemia, underscoring the importance of vigilant postnatal glucose monitoring. Importantly, corticosteroid administration was not associated with increased maternal morbidity or adverse obstetric outcomes. Taken together, these findings suggest that antenatal corticosteroids can be a valuable strategy in managing late preterm pregnancies, provided that adequate neonatal monitoring protocols are in place. Future large-scale studies are warranted to assess long-term outcomes and optimize the balance between benefits and risks.

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