Green 1931.

Methods	Quasi‐RCT, multi‐centred.
Participants	Inclusion criteria: pregnant women. Exclusion criteria: cases not delivered in hospital.
Interventions	Intervention group: 275 women received 1 oz of the vitamin preparation radiostoleum, an amount equivalent in vitamins A and D roughly to 30 oz of a good cod‐liver oil (equivalent to 444,000 IU vitamin A), should have been taken daily commencing 1 month previous to the calculated day of labour. The first 76 cases prior to June 1929 were given the preparation for only 14 days before delivery (daily). It was, however, continued for the first 7 days of the puerperium. It was then decided that a more logical procedure would probably be to begin the administration earlier and thus build up a larger reserve at the time of labour. Control group: 275 women received an untreated version.
Outcomes	Maternal infection (puerperal fever > 38o C) and maternal and baby mortality and morbidity.
Notes	Vitamin A levels were not measured before starting supplementation. Country: UK. Study setting: the Jessop Hospital and the Nether Edge municipal hospital.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"the first patient was given the preparation and the next due for delivery about the same time was indexed as a control."
Allocation concealment (selection bias)	High risk	"the first patient was given the preparation and the next due for delivery about the same time was indexed as a control."
Blinding of participants and personnel (performance bias) All outcomes	High risk	The control group received no intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	50 (8.3%) women delivered somewhere else and were excluded.
Selective reporting (reporting bias)	Unclear risk	The protocol of the study is not available at the moment.
Other bias	Low risk	No other bias awarded.