Methods	Randomised controlled trial of telephone support for improving maternal health outcomes, including smoking cessation during pregnancy Study conducted in a metropolitan city in the south island of New Zealand from March to December 1993
Participants	Inclusion criteria: Women with telephone access, who were either single or with an unemployed partner, less than 20 weeks’ gestation Exclusion criteria: None stated. Recruitment: Recruited in the outpatient department of a large maternity hospital, or its associated GP practices, or self-referral via an introductory letter, phone call, and full discussion of “Healthy Mothers/Healthy Babies” The eligible population was 221 women of whom 49 were never located, 23 were not interested, 10 refused after explanation, and 8 moved away, did not speak English or had a miscarriage. 131 (59%) participated (103 OPD, 22 from GPs, 6 self-referred) (C = 66, I = 65 randomised). Just over 50% were smokers (C = 35, I = 31). Baseline characteristics: Mean cigarettes per day at baseline = 6. 88% European, 10% Maori. 53% single. Progress+ coding: Low SES.
Interventions	Control: Package of publicly available educational material on healthy behaviours during pregnancy. Intervention: Package plus weekly telephone call from trained volunteer with the aim of providing minimal support until 12 weeks after birth; aim “to be a friend and a good listener”; to ask about symptoms; signs; alcohol; drugs; smoking and meals in every call; to encourage attendance at antenatal clinic appointments and to ask about “feeling stressed”. Intervention provided by 19 female volunteers, trained for the project with a “case load” of 2 to 6 women each Main intervention strategy: Social support (single intervention) compared to a less intensive intervention Intensity: Frequency (C = 2, I = 6); Duration (C = 1, I = 4). Intervention provided by project staff: efficacy study.
Outcomes	Self-reported abstinence at 34/40 (late pregnancy*). Mean cigarettes per day*. Anxiety and depression scores at baseline and 34/40. There were other intervention components which might have influenced these outcomes
Notes	No process evaluation is reported. No sample size justification SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer-generated random assignment to control or intervention in balanced blocks of 50
Allocation concealment (selection bias)	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	High risk	Data being reported were analysed on 122/131 of randomised women (control = 63/66, intervention = 59/65). 1 woman requested to be removed from the study, but there were 8 women who for various reasons had incomplete data. p477 4.5% control 9.2% intervention. Only a proportion were smokers (I = 31, C = 35), and the attrition among these is not reported so we were unable to re-include them in the analysis for this review
Selective reporting (reporting bias)	Unclear risk	None apparent.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	High risk	No biochemical validation of reported smoking behaviour.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Caregiver blinded to allocation. Women not blinded to intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	Unclear risk	No process evaluation.
Equal baseline characteristics in study arms	Unclear risk	Baseline psychosocial variables (stress; social support; self esteem; depression; anxiety) reported in Table 2. Demographic variables not reported
Contamination of control group	Unclear risk	Care providers blinded to allocation and not involved in intervention delivery