Objective To examine the effect of periconceptional multi‐micronutrient supplementation on gestation and birth outcomes.Methods A population‐based community intervention program was conducted in 18 counties in China.Participants were divided into an intervention group,who received multi‐micronutrient supplementation from at least 3 months before pregnancy throughout the first trimester,and a control group.Pregnant women were followed up to record information about birth outcomes.Maternal socio‐economic characteristics and main birth outcomes were evaluated.Gestational age was further analyzed using survival analysis,to determine the time distribution of delivery.Results Periconceptional multi‐micronutrient supplementation was associated with higher birth weight,birth length and occipitofrontal head circumference,and with lower incidence rates for stillbirth,low birth weight,and preterm birth.Moreover,periconceptional multi‐micronutrient supplementation changed the time distribution of delivery,making the deliveries more clustered in the period between day 275 and day 295 of gestation.Conclusion Our study shows that periconceptional multi‐micronutrient supplementation is beneficial for fetal development and optimizes all measured aspects of health in neonates in socioeconomically disadvantaged areas in China.The change in time distribution of deliveries caused by multi‐micronutrient supplementation needs further clarification. Objective To examine the effect of periconceptional multi-micronutrient supplementation on gestation and birth outcomes. Methods A population-based community intervention program was conducted in 18 counties in China. Participants were divided into an intervention group, who received multi-micronutrient supplementation from at least 3 months before pregnancy throughout the first trimester, and a control group. Pregnant women were followed up to record information about birth outcomes.Maternal socio-economic characteristics and main birth outcomes time distribution of delivery. Results periconceptional multi-micronutrient supplementation was associated with higher birth weight, birth length and occipitofrontal head circumference, and with lower incidence rates for stillbirth, low birth weight, and preterm birth. Moreover, periconceptional multi-micronutrient supplementation changed the time dist ribution of delivery, making the deliveries more clustered in the period between day 275 and day 295 of gestation. Confclusion Our study shows that periconceptional multi-micronutrient supplementation is beneficial for fetal development and optimizes all measured aspects of health in neonates in socioeconomically disadvantaged areas in China. Change in time distribution of deliveries caused by multi-micronutrient supplementation needs further clarification.