Furness 1975.

Methods	Randomised trial, 3 parallel groups
Participants	Inclusion: bacteriuric (> 100,000 bacteria/mL x 1 or > 10,000 bacteria/mL x 2; midstream urine) at second antenatal visit Setting: South Australia Enrollment period: not stated Number of participants: N = 206
Interventions	Methenamine mandelate or methenamine hippurate 1 g, 4 times a day vs no treatment Treatment continued until delivery
Outcomes	Pyelonephritis (frequency and burning on micturition, pyrexia, or loin tenderness and significant bacteriuria) Preterm birth (defined as less than or equal to 38 weeks' gestation); treatment 24/139 (17%) vs control 10/67 (15%) Mean birthweight: methenamine hippurate 3273 g SE ± 70.7; methenamine mandelate 3303 SE ± 68.2; control 3353 g SE ± 73.9; no difference Postnatal bacteriuria at 6 weeks: 26/73 treatment vs 10/27 no treatment
Notes	Women randomised to either methenamine mandelate (N = 69), methenamine hippurate (N = 70), or no treatment (N = 67); for analyses, treatment groups combined. Unable to separate incidence of pyelonephritis during pregnancy and puerperium; results combined. Dates of study: 1971 to 1972 (estimated) Funding sources: Queen Victoria Research Foundation, South Australia Declarations of interest: none reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	" by random allocation"; no additional details 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	Not placebo‐controlled.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided to permit judgement.
Incomplete outcome data (attrition bias) All outcomes	High risk	20/226 women withdrawn from trial; no details provided. All women included in outcome of pyelonephritis; 17% loss to follow‐up for outcome of low birthweight and gestational age at delivery.
Selective reporting (reporting bias)	High risk	Unable to separate incidence of pyelonephritis during pregnancy and puerperium; results combined.
Other bias	Low risk	The study appears to be free of other sources of bias.
Overall Risk of Bias	High risk	Judged at overall high risk of bias.