Zeng 2008

Methods	Community‐based cluster‐randomised trial conducted in 2 poor rural counties in Shaanxi province of north west China between August 2002 and January 2006.
Participants	Pregnant women of less than 28 weeks' gestation between August 2002 and January 2006. Pregnancy was confirmed using last menstrual period (LMP) and urine pregnancy test.
Interventions	Group A (n = 2017) received folic acid 0.4 mg. Group B (n = 1912) received iron 60 mg and folic acid 0.4 mg. Group C (n = 1899) received iron 30 mg, folic acid 0.4 mg, zinc 15 mg, copper 2 mg, selenium 0.65 mg, iodine 0.15 mg, vitamin A 0.8 mg, B1 1.4 mg, B2 1.4 mg, B6 1.9, B12 0.026 mg, D 0.05 mg, C 70 mg, E 10 mg, niacin 18 mg.
Outcomes	Birthweight, LBW (< 2500 g), SGA (weight < 10 percentile for gestational age), preterm birth (< 37 weeks of gestation), very preterm birth (< 34 weeks of gestation), gestational age, birth length, head circumference, Hb, anaemia (Hb < 110 g/L in third trimester), neonatal deaths (death within 28 days of delivery), early neonatal deaths (death within 7 days of delivery), perinatal deaths (fetal death after 28 weeks of gestation plus early neonatal deaths); and mental and psychomotor development outcomes until 1 year of age by using the Bayley Scales of Infant Development, and growth outcomes (stunting, underweight, and wasting) in children in the first 30 months of life. It should be noted that the data for SGA was obtained from a separate report (Food and Nutrition Bulletin 2009) and not from the individual trial report.
Notes	For review purpose, MMN and iron folate groups are used. Intervention was administered till 6 weeks postpartum. Baseline characteristics at enrolment and both cluster and individual level baseline characteristics were balanced by treatment groups. Stunting, underweight, and wasting data presented as odds ratio and could not be included in the analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The randomisation schedule was generated off site with a pseudo‐random number generator in SAS". Comment: probably done.
Allocation concealment (selection bias)	Low risk	Quote: "The randomisation schedule was generated off site with a pseudo‐random number generator in SAS version 6 (SAS Institute, Cary, NC). A treatment colour code was assigned to each village based on the treatment allocation schedule". Comment: probably done.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Exclusion (4.8%) and attrition (2.3%) were reported along with their reasons.
Selective reporting (reporting bias)	Low risk	Comment: all outcomes mentioned in the methods section were presented in the paper.
Other bias	Low risk	Comment: no other bias was identified.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "double blind", "treatment colour code was assigned to each village based on the treatment allocation schedule. The treatment codes were opened only once all data had been collected and blinded analysis of the primary hypothesis was completed" and "were of identical appearance and packaged in blister packs". Comment: participants and caregivers were blinded to the treatment assignment.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "double blind", "treatment colour code was assigned to each village based on the treatment allocation schedule. The treatment codes were opened only once all data had been collected and blinded analysis of the primary hypothesis was completed". Comment: outcome assessors were blinded to the treatment assignment.

BMI: body mass index Hb: haemoglobin HIV: human immunodeficiency virus IU: international unit IUGR: intrauterine growth retardation LBW: low birthweight LGA: large‐for‐gestational age LMP: last menstrual period mcg: microgram mg: milligram Mg: magnesium MMN: multiple micronutrient RCT: randomised controlled trial RDA: recommended daily allowance SGA: small‐for‐gestational age