Moore 1998.

Methods	RCT 2‐arm trial with individual randomisation. Analysis was stratified by race and age.
Participants	Setting: 1554 women randomised attending community clinics in North Carolina USA. Inclusion criteria: Black women (all ages) white and other women at high risk of preterm birth and white and other women aged 18 or younger. English speaking, access to telephone with gestational age 22‐32 weeks at entry.
Interventions	Intervention group: ‘Women in the intervention group received telephone calls from a registered nurse, one or two times weekly from 24 weeks’ through 37 weeks’ gestation'.'Nurse telephone calls were made on the schedule to which nurse and subject agreed, from the time of the home visit (22–32 weeks’ gestation) until the 37th week. The timing of the calls was designed to suit the woman’s convenience. The goal was three telephone contacts per week. Women without telephones could contact their primary nurse via the nurse’s pager when they were near a telephone. The nurse returned the call immediately. Although no formal script was followed, each telephone call addressed three major areas: assessment of health status (perception of uterine contractions and other pregnancy changes, color of urine as an assessment of hydration, number of meals eaten, number of cigarettes smoked, alcohol and drug use, and ingestion of a prenatal vitamin capsule on the previous day); recommendations based on assessment; and discussion of any additional issues important to the mother. The duration of each call was recorded. Three experienced nurses, hired specifically for the telephone intervention study, conducted the intake interviews and all of the telephone intervention'. ‘Women in the intervention group received additional instruction about the signs of preterm labor, and a schedule was established for the time and frequency of telephone calls they would receive from the nurse, as well as instructions about contacting the nurse by telephoning her pager number’. Women were given a $25 dollar gift voucher if they returned their assessment and remained in contact with the nurse. Control group: standard care. Women were given a booklet about preventing preterm birth which was available in the clinic and routine care. They were given a $10 gift voucher for completing assessments.
Outcomes	LBW or preterm births. Cost data reported for a subsample.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer randomisation table.
Allocation concealment (selection bias)	Low risk	Reported as; ‘Random assignment was directed by the biostatistician. The words “phone” for the intervention group and “book” for the control group were placed in opaque envelopes that were numbered and sealed by the biostatistician’.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Women were not blinded; it was reported that clinical staff were blind to intervention but it was not clear if this was successful. ‘Clinic personnel, including attending physicians, residents, nurses, and others were blinded to group assignment. If a referral to clinic, the labor suite, or another agency was needed, the nurse instructed the patient to make the call and then ascertained that the call was made’.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Data collection was done by an additional nurse hired specifically for this task. She did not participate in the intervention, was not present at any meetings during which patients were discussed, and was blinded to group assignment.’  It is not clear how effective the blinding would actually be in practice.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	121 women randomised; 7.8% changed healthcare providers, moved from the community, or had multiple gestation pregnancies. It was stated that analysis was on an ITT basis.
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	There were no clear differences between groups at baseline; analysis was stratified by age and race.