Berenson 2012.

Methods	Multisite, three‐arm, parallel group, RCT Location: Southeast Texas, USA Time frame: July 2006 to January 2010 Sample size calculation (and outcome of focus): N = 190 in each group (570 total) for 90% power to detect OR of 2.0 for OC continuation after 12 months
Participants	General with N: 1155 women, 16 to 24 years of age Source: 5 public clinics for reproductive health serving low‐income women Inclusion criteria: sexually active; non‐pregnant; 16 to 24 years old; requesting OC initiation. Exclusion criteria: desire to become pregnant in next year; medical contraindication to OC; current or prior (> 1 month) OC use.
Interventions	Study focus: increasing contraceptive adherence and dual‐method use to prevent STI and pregnancy Intervention: Special counseling (SC): standard care (below) plus 45 minutes of contraceptive counseling from study staff; Special counseling plus telephone calls (C + P): SC (above) plus telephone calls by contraceptive counselor (weekly until initiation, then monthly for 6 months) and access to 24‐hour toll‐free number. Comparison: Standard care (S) from nurse provider following a written protocol for new OC users. Duration: 6 months
Outcomes	OC adherence (consistent OC use), pregnancy (self‐report and medical record review) Follow‐up: 3, 6, 12 months
Notes	Trial registration: ClinicalTrials.gov NCT00584038 Funding: Trial was supported by grants from Maternal and Child Health Bureau, Health Resources and Services Administration, and Eunice Kennedy Shriver National Institute of Child Health & Human Development, National Institute of Health. Declaration of interest: no details provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization scheme (PLAN procedure, SAS Institute)
Allocation concealment (selection bias)	High risk	When asked about concealment before assignment, investigator communicated that they did not conceal it from the researchers but did conceal it from the patient.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding of participants due to nature of interventions
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Staff who made assessment telephone calls blinded to intervention group
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow‐up: by 12 months, counseling 44%, counseling + telephone 43%, and standard care 45%
Selective reporting (reporting bias)	High risk	The secondary outcomes of measurement of contraceptive side effects and of sexual activity specified in the protocol registered with ClinicalTrials.gov were not reported in the published manuscript.
Other bias	Low risk	Appeared free of other sources of bias