Wing 2008.

Methods	Study design: 3‐arm RCT Power calculation: no, feasibility pilot Intention‐to‐treat analysis: yes
Participants	Inclusion criteria Setting: 2 centres Country: USA Women < 16 weeks gestation presenting for prenatal care at 1 of 2 centres Number: 188 randomised and analysed Exclusion criteria Underlying medical conditions (e.g. diabetes mellitus, kidney failure, sickle cell disease, chronic hypertension, chronic kidney disease) previous or current antimicrobial therapy; known urological abnormalities
Interventions	Treatment group 1 Cranberry juice: 240 mL at breakfast, placebo juice at other meals Treatment group 2 Cranberry drink: 240 mL, 3 times/d, reducing to twice/d after 52 enrolments because not well tolerated Control group Placebo: 3 daily doses of matched juice product
Outcomes	Primary outcome: asymptomatic bacteriuria, > 108 cfu of a single organism and no symptoms Secondary outcomes Symptomatic bacteriuria, > 108 cfu of single organism and dysuria or frequency or urgency Pyelonephritis, culture as above, + flak pain, fever > 100.4°F, chills nausea, vomiting At least 1 UTI, UTI due to enteric bacteria, Pregnancy outcomes: preterm delivery, spontaneous vaginal delivery, instrumental vaginal delivery, caesarean/caesarean hysterectomy, mean birth weight, low birth weight, 1 min Apgar < 7, 5 min Apgar < 9, admission to NICU, tolerability and compliance
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated randomisation table, stratified by site
Allocation concealment (selection bias)	Low risk	Treatment options were not known to researchers
Blinding of participants and personnel (performance bias) All outcomes	Low risk	States all were blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Clearly stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data are well reported for completeness Losses to follow‐up/withdrawals: 73 withdrawals
Selective reporting (reporting bias)	Low risk	Appropriate outcomes
Other bias	Low risk	Details suggest free of bias, although selection methods a little unclear Source of funding: NS

cfu ‐ colony forming units; CSU ‐ catheter specimen of urine; GFR ‐ glomerular filtration rate; ITT ‐ intention‐to‐treat; MSU ‐ midstream urine; NS ‐ not stated; PAC ‐ proanthocyanidin; SMP ‐ sulfamethoxazole; TMP ‐ trimethoprim; WBC ‐ white blood cell