Respiratory distress syndrome (RDS) is one of the main causes of early neonatal morbidity and mortality, especially in extremely preterm newborns. Respiratory failure in these patients results from a deficit of surfactant and the immaturity of the lungs and other organs.1–3

The antenatal administration of corticosteroids to pregnant women at risk of preterm delivery between 24 and 34+6 weeks of gestation is currently recommended to accelerate lung maturation and reduce the incidence of RDS, among other beneficial effects.2

Infants born preterm between 35 and 36+6 weeks’ gestation have a higher incidence of respiratory complications compared to infants born preterm due to their immaturity, with a reduced catecholamine response and an increase in lung fluid retention. On the other hand, caesarean delivery is another risk factor for the development of respiratory distress in these preterm infants as well as in term infants delivered before 39 weeks’ gestation, especially in case of planned caesarean delivery in the absence of labour, as exposure to uterine contractions stimulates the clearance of foetal lung fluid.4

Some studies have shown that prophylactic corticosteroid administration before planned caesarean deliveries may reduce the incidence and severity of respiratory distress in late preterm and early full-term infants.3,5

In the current literature, the use of antenatal corticosteroid therapy in newborns delivered preterm after 35 weeks’ gestation remains controversial. The American College of Obstetricians and Gynecologists recommends its use in pregnant women at risk of late preterm birth, independently of the mode of delivery, and does not recommend it in case of caesarean delivery at term.

On the other hand, the Royal College of Obstetricians and Gynaecologists of the United Kingdom does recommend the use of antenatal corticosteroids in planned caesarean deliveries to be performed before 38+6 weeks’ gestation to reduce the risk of neonatal respiratory distress.6

The obstetricians in the hospital that participated in the study presented here, adhering to the latter recommendation, implemented a new protocol in 2013 by which antenatal corticosteroids were administered before planned caesarean deliveries with absence of labour performed between 35+0 and 38+6 weeks’ gestation. The dosage consisted of 1 dose of intramuscular betamethasone given 24h before the caesarean section.

We conducted a retrospective analytical study of all planned caesarean deliveries performed between 35+0 and 38+6 weeks’ gestation in a tertiary care hospital from January 2013 to April 2017.

During the study period, there were a total of 285 caesarean deliveries, of which 208 (73%) were planned and performed in the absence of labour.

Of all planned caesarean deliveries, 80.8% were performed at term (37–38 weeks) and 19.2% preterm (35–36 weeks).

The proportion of planned caesarean delivery was higher in SGA newborns, a difference that was statistically significant (34/38 [89%] vs. 174/245 [71%]; P=.016) (Fig. 1).

Figure 1.

Percentage of planned caesarean delivery in infants born small for gestational age versus those born adequate for gestational age. Chi square test, P=.016.

SGA, small for gestational age.

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Antenatal corticosteroids were given in 97 (46.6%) of the cases of planned caesarean delivery in which they were indicated.

The administration of antenatal corticosteroids where indicated was more frequent in PT newborns compared to FT newborns, a difference that was statistically significant (30/40 [75%] of PT vs. 67/168 [39.9%] of FT newborns; P<.001).

In all gestational age groups, most identified cases of immediate respiratory distress corresponded to transient tachypnoea (20), while the rest corresponded to hyaline membrane disease (2), pneumonia (1), pulmonary hypertension (1) and apparent life-threatening event (1).

Without taking into account the administration of corticosteroids, the proportion of respiratory distress in cases of planned caesarean delivery was greater in the group of PT infants delivered between 35 and 36 weeks’ gestation compared to FT infants delivered between 37 and 38 weeks, a difference that was statistically significant (respiratory distress, 12/40 PT newborns [30%] vs. 13/168 FT newborns [7.8%]; P<.001), and in the subset born at term, the proportion of respiratory distress was higher in the newborns delivered at 37 weeks compared to those delivered at 38 weeks (respiratory distress, 6/60 of those born at 36 weeks [10%] vs. 7/108 of those born at 38 weeks [6.5%]) (Fig. 2).

Figure 2.

Percentage of respiratory distress (RD) in newborns delivered by planned caesarean section by gestational age. Chi square test, P<.001.

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The distribution of cases of planned caesarean delivery based on the administration or lack of administration of antenatal corticosteroids was similar when compared based on sex, presence of oligohydramnios, presence of meconium in amniotic fluid and presence of chorioamnionitis in both gestational age groups. There was a higher frequency of antenatal corticosteroid prophylaxis in the group where the planned caesarean delivery was performed at 35 or 36 weeks’ gestation in mothers without diabetes compared to mothers with diabetes (27/33 [81.8%] vs. 3/7 [42.8%]), although this difference was not statistically significant (Table 1).

We did not find significant differences in the incidence of respiratory distress between the group treated with antenatal corticosteroids and the group that did not receive this treatment in either of the 2 gestational age groups (Fig. 3). We also did not find significant differences in the need of admission to the ward, admission to the NICU, mechanical ventilation or NIV or in the development of hypoglycaemia. Table 2 presents these results (summary of qualitative variables).

Figure 3.

Percentage of respiratory distress (RD) in newborns delivered by planned caesarean section by administration of corticosteroids and gestational age.

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In the comparison of the groups of infants delivered by planned caesarean section exposed and not exposed to antenatal corticosteroids, we did not find any differences in the length of stay, duration of NIV, maximum FiO2 or Apgar score at 1min and 5min in either of the gestational age groups. Table 3 presents these results (summary of quantitative variables).

The administration of antenatal corticosteroids in pregnant women at risk of preterm birth before 34+6 weeks’ gestation is currently recommended (grade A1 recommendation) to accelerate lung maturation and reduce the incidence and severity of RDS associated with the deficit of surfactant in these newborns.1,2 Furthermore, antenatal corticosteroids also reduce perinatal and neonatal mortality and the incidence of necrotising enterocolitis and intraventricular haemorrhage. A single course of corticosteroids does not seem to have any short-term adverse effects in either the mother or the newborn.7

Late PT newborns (born at 34–36 weeks’ gestation) had respiratory morbidity more frequently than FT newborns. On the other hand, caesarean delivery is an additional risk factor for the development of respiratory distress both in PT and FT newborns, especially in the absence of labour.3

The usefulness of antenatal steroids in late PR and early FT infants delivered by planned caesarean section is still under debate.

Based on several studies in the literature, antenatal corticosteroid prophylaxis in case of delivery between 34 and 36 weeks’ gestation is associated with a reduction of respiratory morbidity (severe RDS and transient tachypnoea) in the short term, but not with a reduction in mortality.8–10 There are limitations to these studies, some due to their design, others for including infants born at 34 weeks’ gestation in the analysis, others for not differentiating between modes of delivery, not to mention that they use different corticosteroid regimens (selected corticosteroid, number of doses). The data on the long-term effects and outcomes of antenatal corticosteroid administration are scarce.

When it comes to the administration of corticosteroids before performance of planned caesarean sections at term, the most recent Cochrane review found that it can reduce the risk of respiratory distress and admission in to intensive care due to respiratory morbidity, and no difference in relation to the need of conventional mechanical ventilation or mortality. The authors of the review described limitations in the design of these studies and reported that further studies with larger samples would be required to obtain valid results.11

The regimen used in these studies included at least 2 doses of dexamethasone or betamethasone. There are also still few long-term follow-up data on these newborns.12

Thus, there is also no clear evidence on the optimal regimen for antenatal corticosteroid therapy in terms of the type of corticosteroid, number of doses, interval between doses and timing of administration, which have varied between published studies.12–16

The regimen used in the study in our hospital consisted of 1 dose of betamethasone 24h before the planned caesarean delivery at 35+0 to 38+6 weeks’ gestation. Our results differ from those described by other authors.4,8 This may be due in part because other studies have included PT newborns delivered at 34 weeks’ gestation, who are at higher risk of distress compared to newborns with greater gestational ages, and who are more likely to benefit from the prenatal lung maturation induced by corticosteroids. In addition, the regimens used in other studies were different and included 2 doses of betamethasone or dexamethasone, which could have contributed to the differences in the results.

On the other hand, our study has limitations due to its retrospective design and the small sample size in some of the analyses. Another limitation is the lack of universal adherence to the indications for the administration of corticosteroids. This last factor may be due to the initial lack of awareness of the staff after the introduction of the new protocol, as we found that adherence had increased in the last 3 years.

The performance of this study and its findings have contributed, on one hand, to remind staff of the need to adhere strictly to the protocol, and on the other to propose a future prospective study comparing the administration or lack thereof of antenatal corticosteroids or different steroid regimens.

In addition, when we analysed the results of our study we found that, as described in other case series,17 the proportion of patients with respiratory distress and with admission related to planned caesarean section increased with decreasing gestational age in both FT and PT newborns. In our sample, most planned caesarean deliveries occurred in term pregnancies, and delivery by caesarean was more frequent in SGA newborns, probably because SGA was one of the indications for this mode of delivery.

In our study, we did not find significant differences in the benefit of the administration of a single dose of antenatal corticosteroids in planned caesarean deliveries performed between 35+0 and 38+6 weeks’ gestation for reduction of respiratory distress in newborns.

We also found no differences in the need or duration of NIV, admission to NICU, length of stay, percentage requiring supplemental oxygen, Apgar score at birth or the development of hypoglycaemia.

Further studies are required to determine the most appropriate form and schedule of corticosteroid therapy and the long-term outcomes of its administration in exposed newborns.

In this case series, consistent with previous ones, the development of respiratory distress was significantly more frequent in PT newborns compared to FT newborns, and in the latter subset, more frequent with decreasing gestational age. Therefore, delaying performance of planned caesarean deliveries, where possible, could contribute to decreasing the respiratory distress associated with prematurity and the lack of exposure to labour.

The authors have no conflicts of interest to declare.