11. Effects of 'cross‐cutting' interventions.

Study	Quality assessment						Outcome	No of participants		Relative effect (95% CI) or P value	Certainty (GRADE)
	Design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other Considerations		Intervention	Control
Ayres‐De‐Campos 2015	ITS	Seriousa	Single study	Not serious	Not serious	None	In the period between 2009 and 2014, representing the possible influence of the concerted action: the CS rate in the study region decreased by 20.0% (from 36.0 to 28.8%, time trend P < 0.001)b; rates of instrumental vaginal delivery increased by 33.1% (from 13.7 to 18.2%, time trend P < 0.001), VBAC increased by 99.8% (from 16.4 to 32.8%, time trend P < 0.001), while perineal lacerations increased by 45.2% (from 0.42 to 0.61%, time trend P < 0.001)b; the incidence of hypoxia‐related complications decreased by 14.1% (from 0.71 to 0.61%, time trend P < 0.001)b				㊉㊀㊀㊀ VERY LOWa
Runmei 2012	CBA (reanalysed as ITS)	Seriousa	Single study	Not serious	Not serious	None	CS	Change in level of caesarean deliveries during intervention: ‐13.4% (95% CI ‐19.6% to ‐7.1%)b; change in slope of caesarean deliveries: ‐0.72% (95% CI ‐3% to 1.5%)b			㊉㊀㊀㊀ VERY LOWa
							Maternal morbidity	"We found a significant increase in the incidence of all obstetric complications, with the exception of placental abruption, after 2004..."
							Neonatal morbidity	"The incidence of birth asphyxia did not increase after 2004 (P = 0.303)"
About the certainty of the evidence (GRADE)* High: this research provides a very good indication of the likely effect; the likelihood that the effect will be substantially different† is low. Moderate: this research provides a good indication of the likely effect; the likelihood that the effect will be substantially different† is moderate. Low: this research provides some indication of the likely effect; however, the likelihood that it will be substantially different† is high. Very low: this research does not provide a reliable indication of the likely effect; the likelihood that the effect will be substantially different† is very high. *This is sometimes referred to as 'quality of evidence' or 'confidence in the estimate' †Substantially different = a large enough difference that it might affect a decision
CBA: controlled before‐after; CI: confidence interval; CS: caesarean section; ITS: interrupted time series; VBAC: vaginal birth after caesarean. aDowngraded one level for serious risk of bias (due to possible confounding of outcome, unclear whether the intervention occurred independently of other changes over time). bTwo standardised effect sizes are obtained from interrupted time series analysis: a change in level (also called ‘step change’) and a change in trend (also called ‘change in slope’) before and after the intervention. Change in level = difference between the observed level at the first intervention time point and that predicted by the pre‐intervention time trend; change in trend = difference between post‐ and pre‐intervention slopes. A negative change in level and slope indicates a reduction in caesarean section rate.