Abstract: Background and Objective: Pregnancy exacerbates iodine deficiency and therefore increases the risk of subclinical hypothyroidism (SCH). This study examines the links between iodine deficiency in pregnancy and subclinical hypothyroidism on one hand and preeclampsia, oxidative stress and carotid intima-media thickness on the other hand. Materials and Methods: This case-control study involved 200 participants with preeclampsia. The controls were 150 age-matched pregnant women without preeclampsia with complete data. Carotid intima-media thickness (cIMT), nitric oxide (NO), urinary iodine concentration (UIC), serum thyroid-stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) were measured and compared across controls, mild preeclampsia cases and severe preeclampsia/eclampsia cases using one-way ANOVA. A p<0.05 was considered statistically significant. All analyses were performed using the SPSS for windows version 23.0. Results: There was a significant negative association along a biologic gradient of mean UIC and NO: Controls, cases with mild preeclampsia and cases with severe preeclampsia/eclampsia (p<0.0001). However, there was a significant positive association along a biologic gradient of mean TSH, T3, T4 and cIMT: Controls and cIMT cases with mild preeclampsia and cases with severe preeclampsia/eclampsia (p<0.0001). Conclusion: Iodine deficiency and its associated pro-oxidant subclinical dysthyroidism is not only a risk factor for preeclampsia with elevated cIMT vascular stiffness and oxidative imbalance related to TSH and NO but also for future cardiovascular diseases among women of reproductive age.