Methods	Randomised controlled trial of psychosocial support in pregnancy which aimed to improve maternal health, including reducing smoking during pregnancy Conducted in 4 countries in Latin America (Argentina, Brazil, Cuba, and Mexico) from January 1989 to March 1991
Participants	Inclusion criteria: High-risk women whose antenatal care began at 15-22 weeks’ gestation, singleton pregnancy, 1 or more of the following: prior LBW infant; preterm birth; perinatal/infant death; < 18 years; body weight <= 50 kg; height <= 150 cm; low family income (local definitions applied); < 3 years school; crowded household (4 or more persons/bedroom); smoking; not living with husband or partner. Exclusion criteria: Heart or renal failure; diastolic BP > 100 mmHg; history of cervical cerclage; Rh negative; mental disease or any chronic disease that might interfere with pregnancy Recruitment: 2,235 women met eligibility criteria and gave consent (I = 1115-though 1110 in table, C = 1120) Baseline characteristics: Smokers (I = 23.9%, C = 21.8%), with variation between countries - Argentina (I = 21.9%, C = 20.6%), Brazil (I = 40.7%, C = 33.1%), Cuba (I = 27.4%, C = 28.9%), Mexico (I = 9%, C = 6.8%). Mean cigarettes per day at randomisation: C = 7.9, I = 7.5 Progress+ coding: Low SES based on place of residence (low family income 20% in Cuba, 52% in Mexico, 53% in Brazil and 100% in Argentina)
Interventions	Control: Routine antenatal care, otherwise unspecified. Intervention: Flexible use of a standardised manual, based on site-specific ethnographic studies of needs, fears, expectations, social support networks, including detailed descriptions of situations likely to occur during home visits. 4 to 6 home visits of 1 to 2 hours with emphasis on psychosocial support, education on health habits including better nutrition, reducing smoking alcohol and other drugs, reducing their physical workload, recognition of alarm signs and symptoms, improved access to hospital facilities, reinforcement of health service utilisation. Additional components were a poster, a booklet, hotline to project office, guided tour of hospital, encouragement of family support and participation. Intervention was provided by specially trained female social workers or obstetric nurses with previous experience of childbirth Main intervention strategy: Social support (tailored) compared with usual care. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 5). Usual care frequency and duration = 0 (unclear). Intervention provided by study team: efficacy study.
Outcomes	Self-reported point prevalence abstinence at 36 weeks’ gestation (late pregnancy*); Mean cigarettes per day.* Multiple perinatal and maternal health outcome data were collected, but not included in this review as other aspects of the intervention may have had an impact Baseline state anxiety score.
Notes	Sample size was planned for the primary trial objective.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Centrally prepared, method not stated.
Allocation concealment (selection bias)	Low risk	Allocation was by opening sealed, opaque envelopes.
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition 202/2230 (9%): 101 in each arm. Unclear what attrition among smokers and no ITT analysis of drop-outs as continuing smokers, so not able to re-include smokers who dropped out in 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	High risk	Home visitors were aware of group allocation. Social support intervention with home visits
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The evaluation of the interventions was conducted by a team of independent professional interviewers who were not informed of the characteristics of the study
Incomplete implementation	Low risk	Most (83%) of the women randomly assigned to the intervention group received the planned number of home visits, and 90% were visited at least once
Equal baseline characteristics in study arms	Low risk	The distribution of risk factors was similar in the 2 groups and the 2 groups had similar demographic, obstetric, and psychological characteristics at baseline
Contamination of control group	Low risk	The clinic personnel were unaware of the identity of the women in the control group, and no attempts were made to inform them of which women were in the intervention group. Health educators providing intervention were separate from care providers