Summary of findings 1. Effect of antenatal corticosteroids (betamethasone) compared to usual care prior to planned caesarean at term on maternal and neonatal outcomes.

Antenatal corticosteroids compared to usual care prior to planned caesarean at term on maternal and neonatal outcomes
Patient or population: women undergoing planned elective caesarean section at 37 weeks' gestation and beyond for singleton pregnancy  Setting: obstetric units from 10 UK hospitals Intervention: two intramuscular doses of 12 mg of betamethasone administered 24 hours apart Comparison: usual care without antenatal steroids
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with usual care	Risk with Antenatal corticosteroids
Respiratory distress syndrome (RDS)	Study population		RR 0.34 (0.07 to 1.65)	942 (1 RCT)	⊕⊕⊝⊝ LOW 1, 2	It is uncertain if antenatal corticosteroids have any effect on risk of RDS compared with usual care.
	11 per 1000	4 per 1000 (1 to 17)
Transient tachypnoea of the neonate (TTN)	Study population		RR 0.52 (0.25 to 1.11)	942 (1 RCT)	⊕⊕⊝⊝ LOW 1, 2	It is uncertain antenatal corticosteroids have any effect on risk of TTN compared with usual care.
	40 per 1000	21 per 1000 (10 to 44)
Admission to neonatal special care (all levels) for respiratory morbidity	Study population		RR 0.45 (0.22 to 0.90)	942 (1 RCT)	⊕⊕⊕⊝ MODERATE 1	Antenatal corticosteroids probably reduce the risk of admission to neonatal special care for respiratory complications compared with usual care.
	51 per 1000	23 per 1000 (11 to 45)
Need for mechanical ventilation	Study population		RR 4.07 (0.46 to 36.27)	942 (1 RCT)	⊕⊝⊝⊝ VERY LOW 1, 3	It is uncertain if antenatal steroids have any effect on the risk of needing mechanical ventilation compared with usual care.
	2 per 1000	9 per 1000 (1 to 76)
Neonatal hypoglycaemia	Study population		Not estimable	0 studies	‐	Outcome not reported in included trial
	0 per 1000	0 per 1000
Maternal mortality and severe morbidity	Study population		Not estimable	0 studies	‐	Outcome not reported in included trial
	0 per 1000	0 per 1000
Maternal development of postpartum infection/pyrexia in the first 72 hours	Study population		Not estimable	942 (1 RCT)	⊕⊝⊝⊝ VERY LOW 1, 4	It is uncertain if antenatal steroids have any effect on the risk of maternal development of postpartum infection/pyrexia. One trial reported zero cases of postpartum infection/pyrexia in the first 72 hours.
	0 per 1000	0 per 1000
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RR: risk ratio
GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

¹Downgraded one level for serious risk of bias: lack of blinding could influence outcomes

²Downgraded one level for serious imprecision: low event rate and 95% confidence interval that spans possible benefit and possible harm

³Downgraded two levels for very serious imprecision: very low event rate and wide 95% confidence interval that spans possible benefit and possible harm

⁴Downgraded two levels for very serious imprecision: zero events