Gallot 2007.

Study characteristics
Patient Sampling	Study design: population‐based retrospective cohort study Recruitment: malformations in neonates, still births and fetuses following termination of pregnancy in the region are registered in the database based on data collected from maternity wards, paediatric units, cytogenetic laboratories, pathology laboratories, departments of medical genetics and birth certificates Study start and end date: January 1986 to December 2003
Patient characteristics and setting	Setting: Central‐Eastern France Registry database Region(s) and country/countries from which participants were recruited: Central‐Eastern France Sample size: 1,834,972 Study eligibility criteria: registered infants aged 1 year or younger with a verified diagnosis of congenital diaphragmatic hernia Number of participants with the target condition: 451 Population type: unselected population Prior testing: not reported
Index tests	Type: two‐stage screening First‐trimester scan: Timing (weeks and days gestation): at the end of the first trimester Ultrasound scanning protocol: not reported Cardiac screening: not reported Mode of examination: not reported Single or multiple operators: multiple (population‐based) Staff qualification and/or operator experience level: not reported Second‐trimester scan: Timing: 22 to 24 weeks’ gestation Ultrasound scanning protocol: not reported Cardiac screening: not reported Mode of examination: not reported Single or multiple operators: multiple (population‐based) Staff qualification and/or operator experience level: not reported
Target condition and reference standard(s)	Target condition(s): congenital diaphragmatic hernia Definitions used for major and minor congenital abnormalities: not reported Reference standard (live birth): data on postnatal diagnostic findings collected from maternity wards and paediatric units. Other sources of information include cytogenetic laboratories, pathology laboratories, departments of medical genetics and birth certificates. Reference standard (fetal or neonatal demise): if available, pathology reports Postnatal follow‐up duration: infants with malformations are registered after discharge up to the age of 1 year
Flow and timing	Eligible patients: 1,835,022 Exclusions (study investigator): none reported Exclusions (review team): 50 (missing information on gestational age at time of prenatal diagnosis based ‐ data supplied by authors)
Comparative
Notes	Funding source: the ‘ARDEMO’ team was supported by the French Research Department (JE2447). The primary author, D. Gallot, was supported by a grant from the Société Française de Médecine Périnatale and from the Collège National des Gynécologues et Obstétriciens Français. V. Sapin was supported by an INSERM grant (Contrat d’Interface).
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Could the selection of patients have introduced bias?		Low risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (First‐trimester scan)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 2: Index Test (First + second‐trimester scan)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 2: Index Test (Single second‐trimester scan)
DOMAIN 3: Reference Standard
Is the reference standard likely to correctly classify anomalies that are externally visible, present with clinically relevant symptoms shortly after birth, or that are considered to be lethal/incompatible with life?	Yes
Is the reference standard likely to correctly classify anomalies that may present after discharge from postnatal care?	Yes
Were the reference standard results interpreted without knowledge of the results of the index test?	No
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Did all live‐born infants receive a reference standard?	Yes
Did all live‐born infants receive the same reference standard?	No
Did all cases of fetal or perinatal loss receive the reference standard (including termination of pregnancy, intra‐uterine death, stillbirth, perinatal mortality)?	Unclear
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Unclear risk