Methods	Randomisation by opaque sealed envelopes.
Participants	2000 pregnant women attending the ultrasound department for routine third trimester scans, including multiple pregnancies
Interventions	All women were offered routine early pregnancy ultrasound and 2 routine scans in the third trimester. Placental grading was performed at the routine third trimester scan. The results of placental grading in the study group were revealed, and the control group concealed. Clinical management in both groups was left entirely to the clinician responsible for care
Outcomes	Obstetric interventions (antepartum and intrapartum) and perinatal outcome indices
Notes	This study addresses the value of placental grading at routine third trimester ultrasound
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Described as “randomly allocated to 1 of 2 groups”.
Allocation concealment?	Yes	Described as “a correspondingly numbered, sealed, opaque envelope”
Blinding? Women	No	Not feasible.
Blinding? Clinical staff	No	Not feasible.
Blinding? Outcome assessors	No	Not feasible.
Incomplete outcome data addressed? All outcomes	Yes	No losses to follow up.
Free of selective reporting?	Yes	Selective outcome reporting not detected.
Free of other bias?	Yes	No other bias apparent.