IntroductionThe World Health Organization has suggested preconception care to improve pregnancy outcomes. Hence, the study aimed to compare the effect of preconception care on pregnancy outcomes, particularly prematurity and low birth weight. MethodsWe carried out interventions in one tribal and one non-tribal block. For comparison, one adjacent tribal block and one non-tribal block were included in Nashik district, India. The total study period was from April 2018 to July 2021. All reproductive age group women desiring pregnancy within one year in selected four blocks participated in the study. The services included clinical examination, laboratory investigations, treatment, six-monthly deworming, anemia management, folic acid supplementation, family planning services, and behavioral change communication using different media. The existing healthcare workers provided services to the women until they became pregnant or until the end of the follow-up period (27 months). We monitored pregnancy outcomes, including abortion, stillbirth, and live birth; among live births, low birth weight, preterm birth, congenital physical anomaly, and neonatal death. ResultsThe study enrolled 7,875 women, and 3,601 had outcomes. The proportion of preterm births in the intervention and comparison block was 11.18 % and 14.99 %, respectively (p = 0.001), and the proportion of low-birth-weight babies was 9.23 % and 11.25 %, respectively (p = 0.01). The adjusted prevalence ratio showed that the risk of preterm births in the absence of intervention was 1.3 (CI: 1.1–1.6). Preterm birth was a mediator between preconception care and low birth weight. ConclusionReduction in proportion of low birth weight and preterm babies can be achieved through preconception care using minimal additional resources.