Williams 1969.

Methods	Randomised trial; 2 parallel groups
Participants	Inclusion: bacteriuria (> 100,000 bacteria/mL x 2, midstream urine) at first antenatal visit Setting: University Hospital, Cardiff, Wales Number of subjects: N = 163
Interventions	Sulphadimidine 1 g, 3 times a day x 7 days, nitrofurantoin 100 mg twice a day, or ampicillin 250 mg, 3 times a day x 7 days for failures (N = 85), or no treatment. For no treatment group, sulphadimidine 1 g, 3 times a day x 7 days if symptoms presented (frequency, dysuria, fever, or loin pain), (N = 78)
Outcomes	Pyelonephritis (loin pain with tenderness or fever, or both); includes postpartum infection (n = 6)
Notes	No loss to follow‐up Dates of study: 1967 Funding sources: United Cardiff Hospitals Declarations of interest: none reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"allocated at random"; no additional information provided to permit judgement
Allocation concealment (selection bias)	Unclear risk	No information provided to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding; outcome may have been influenced by lack of blinding. No treatment group was given antibiotics to take if symptoms of infection developed.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No blinding; assessment of outcome (pyelonephritis) may have been influenced by knowledge of treatment allocation.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No explanation for unequal group sizes; no information provided on any missing data. An unknown number of women in the control group (no treatment) were given antibiotic treatment if they developed symptoms of urinary tract infection.
Selective reporting (reporting bias)	High risk	No pregnancy outcomes (gestational age, birthweight)
Other bias	Low risk	The study appears to be free of other sources of bias.
Overall Risk of Bias	High risk	Judged at high risk of bias