Abstract Background: Thyroid dysfunction is one of the commonest endocrine disorders encountered during pregnancy after diabetes mellitus. Pregnancy develops major changes in hypo thalamic pituitary thyroid axis, iodine metabolism and the immune function. Thyroid physiology alters in order to meet increased metabolic demands in pregnancy. Pre-eclampsia is much more common in women who are pregnant for the first time. Women who have previously been diagnosed with pre-eclampsia are also more likely to experience pre-eclampsia in subsequent pregnancies. Aim of Study: The aim of this study was to identify the prognostic value of thyroid function tests between 11 and 13 weeks of pregnancy as predictor of preeclampsia occurrence. Patients and Methods: This study was a prospective observational (cohort) study. This study was done in Obstetrics & Gynaecology Department, Shubrakhet Hospital From Jan. 2021 – Oct. 2021. Subjects was women attending for their routine first hospital visit in pregnancy, which is held at 11+0 to 13+6 weeks of gestation and followed-up until delivery. Results: The results of our study showed that there was no significant difference between the two studied groups (preeclampsia and normal pregnant group) regarding maternal age, BMI, gestational age. The blood pressure was significantly high in preeclampsia group. The incidence of Hypothyroidism was significantly higher in preeclampsia group (63.3% more than the normal pregnant group (18.3%). Conclusion: The results of the present study showed that there were a significant different in T3, T4 and TSH levels between preeclampsia and healthy pregnant women. There was association between thyroid abnormalities and pregnancy caused hypertension.