What is the issue?
Babies born at term (at or after 37 weeks) by planned (elective) caesarean section and before onset of labour are more likely to develop respiratory complications than babies born vaginally. The giving of injections called 'corticosteroids' to the mother has been shown to reduce the risk of newborn babies having breathing problems in babies born before 34 weeks, but it is not clear if they are useful after this stage.
Why is this important?
The risk of respiratory complications, mostly respiratory distress syndrome and transient tachypnoea, decreases from 37 weeks to 39 weeks of gestation, at which stage it is low. The aim of this review was to investigate if corticosteroids can reduce the rates of respiratory problems and the need for admission into special care units when given before planned (not emergency) caesarean section at term.
What evidence did we find?
The review identified four randomised controlled studies involving 3956 women and 3893 babies, which compared corticosteroids with usual care or placebo. Giving the mother intramuscular antenatal corticosteroids may reduce the chances of a baby needing special care for respiratory problems, and may reduce the chances of the baby being admitted to a neonatal intensive care unit. Much larger numbers of women would be needed to confirm differences in the rates of the respiratory problems themselves and any possible harms of giving the corticosteroids, for the mother and the baby.
Quality of evidence
The quality of evidence from the included randomised trials was low. This means that we can not be completely confident that future trials will come to the same conclusions about the treatment benefits for the babies of mothers receiving a course of antenatal corticosteroids prior to caesarean section.
What does this mean?
Evidence suggest that there might be a beneficial effect of intramuscular corticosteroids in respiratory outcomes of the neonate in the immediate period after birth. Given that only one study has examined the long-term effects, we cannot be certain about whether there are risks and what is their magnitude. Larger randomised trials should be conducted in order to confirm the short- and long-term effects of this intervention in the general population of women undergoing elective caesarean section.
The results from the four trials are promising, but more high-quality studies with larger sample sizes that are adequately powered to detect the effect of prophylactic antenatal corticosteroids on outcomes of respiratory morbidity are needed, given the potential of the current studies for bias. Consideration should be given to the balance between statistical significance and clinical significance, particularly in view of the low event rates of significant respiratory morbidity (RDS or admission to NICU for respiratory complications) in this population. In addition, further trials on the long-term outcomes of these infants are needed to identify any potential harms and complications of antenatal corticosteroid administration at term.
Infants born at term by elective caesarean section are more likely to develop respiratory morbidity than infants born vaginally. Prophylactic corticosteroids in singleton preterm pregnancies accelerate lung maturation and reduce the incidence of respiratory complications.
The objective of this review was to assess the effect of prophylactic corticosteroid administration before elective caesarean section at term, as compared to usual management without corticosteroids, in reducing neonatal respiratory morbidity and admission to special care with respiratory complications.
We searched Cochrane Pregnancy and Childbirth's Trials Register (14 June 2017), and reference lists of retrieved studies.
Randomised controlled trials comparing prophylactic antenatal corticosteroid administration (betamethasone or dexamethasone) with placebo or with no treatment, given before elective caesarean section at term (at or after 37 weeks of gestation).
Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of the evidence using the GRADE approach.
We included four trials (3956 women and 3893 neonates) at a moderate risk of bias, comparing prophylactic administration of betamethasone or dexamethasone versus placebo or usual treatment without steroids in term elective caesarean section. Women randomised to treatment group received either two intramuscular doses of betamethasone in the 48 hours before delivery, or intramuscular dexamethasone (two or four doses) prior to delivery (at 37 weeks' gestation or 48 hours before delivery), and were compared to the control group who received a saline placebo or treatment as usual.
Prophylactic antenatal corticosteroid administration appeared to decrease the risk of respiratory distress syndrome (RDS) (risk ratio (RR) 0.48; 95% confidence interval (CI) 0.27 to 0.87; 4 studies; 3817 participants; low-quality evidence), transient tachypnoea of the neonate (TTN) (RR 0.43; 95% CI 0.29 to 0.65; 4 studies; 3821 participants; low-quality evidence), admission to the neonatal intensive care unit (NICU) for respiratory morbidity (RR 0.42; 95% CI 0.22 to 0.79; 3 studies; 3441 participants), and admission to neonatal special care (all levels) for respiratory complications (RR 0.45; 95% CI 0.22 to 0.90; 1 study; 942 participants; low-quality evidence). Administration of antenatal corticosteroids also appeared to reduce admission to neonatal special care (RR 0.62; 95% CI 0.43 to 0.89; 2 studies; 2169 participants) and neonatal intensive care (RR 0.14; 95% CI 0.03 to 0.61; 1 study; 452 participants) for any indication, compared to placebo or usual care. Finally, prophylactic antenatal corticosteroids also appeared to reduce the length of stay in NICU by 2.70 days (mean difference (MD) -2.70; 95% CI -2.76 to -2.64; 2 studies; 32 participants).
No reduction was found in the need for mechanical ventilation (RR 0.67; 95% CI 0.27 to 1.68; 3 studies; 3441 participants; very-low quality), perinatal death (RR 0.67; 95% CI 0.11 to 4.10; 4 studies; 3893 participants) or neonatal sepsis (RR 1.00; 95% CI 0.06 to 15.95; 2 studies; 2214 participants) .
There were no reported events of neonatal respiratory complications (other than RDS and tachypnoea of the newborn (TTN)), chronic lung disease, duration of mechanical ventilation or maternal postpartum infection, therefore results on these outcomes are non-estimable. The studies did not provide data on other pre-defined outcomes.
The quality of evidence, as assessed using GRADE was low for the outcomes of RDS, TTN and admission to NICU for respiratory morbidity, indicating that the true effect could potentially be substantially different from our estimate of effect.