Methods	Randomised by women selecting one of a number of envelopes (< 6) containing a computer-generated random 1 or 2 and a study number
Participants	All pregnant women who attended antenatal clinic < 24 weeks’ gestation, i.e. unselected population. Multiple pregancies excluded once diagnosed (and study numbers reused). 1527 women
Interventions	All women had a dating scan 16-24 weeks’ gestation. Study group had a further scan at 32-36 weeks’ gestation (ideally 34 weeks’ gestation) which aimed to detect small-for-gestational-age fetuses, and if estimated fetal weight fell below the 20th centile for gestation, this was reported and additional scans recommended but not arranged. Clinicians were able to order further scans for the control group if clinically indicated
Outcomes	Mainly perinatal outcome indices. Number of further ultrasound scans
Notes	Scan to detect small-for-gestational age.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Described as “randomised controlled trial”.
Allocation concealment?	Unclear	Not stated.
Blinding? Women	No	Not feasible.
Blinding? Clinical staff	No	Not feasible.
Blinding? Outcome assessors	No	Not feasible.
Incomplete outcome data addressed? All outcomes	Unclear	Not stated.
Free of selective reporting?	Unclear	No information provided.
Free of other bias?	Unclear	No information provided.