In this study, we investigated the associations of maternal dietary iron intake during the first trimester of pregnancy and pregnancy outcomes and related complications in pregnant women of Isfahan, Iran. In this prospective study, 812 healthy first-trimester singleton pregnant women were selected randomly from 20 various health centers across Isfahan city during 2015-2016. The maternal dietary iron classified into 2 groups, including heme and non-heme iron. Factors including pre-eclampsia, gestational hypertension, gestational diabetes mellitus, intrauterine growth restriction (IUGR), and nausea and vomiting in pregnancy considered as the pregnancy-related complications. Infant's birth weight, birth height, and birth head circumference were also determined as the pregnancy-outcomes. There was a significant association between total iron consumption and infant head circumference (p = 0.01). Total maternal iron (the sum of heme and non-heme iron) was negatively associated with both infant's birth height (p = 0.006) and birth weight (p = 0.02). Non-heme iron consumption is positively associated with high-risk of IUGR (p = 0.004). Heme intake was associated with an increased risk of maternal fasting blood sugar (FBS) (p = 0.04). Higher heme, non-heme, and total iron intake were associated with lower risk of pre-eclampsia (heme: crude p = 0.05; non-heme iron: adjusted p = 0.02; total iron: adjusted p = 0.05). Maternal total iron intake was directly associated with infant head circumference, whereas, negatively associated with both birth weight and birth height. High non-heme iron intake may increase the risk of IUGR, and a high intake of heme iron may increase FBS.