Mineral ions known as electrolytes govern the osmolality of interior biological systems and losing them can be deadly. Electrolyte imbalances have been linked to a wide range of pregnancy health issues, including contractility of smooth muscle, spasms of the muscles, and body aches, as well as heart palpitation, breathing difficulties, cardiac dysrhythmia (which can cause cardiac arrest or paralysis of the lungs), chronic kidney disease, and hypertension. As the third trimester is the critical period in pregnant accompanied with complications like preeclampsia this study designed for investigating electrolytes levels (calcium, potassium, sodium, phosphate, chloride) in 3rd trimester of normal Iraqi pregnant women compared with non-pregnant women as control group. This study is the first case-control study on pregnant women carried out in Diyala Province in Iraq highlighting electrolytes imbalance associated with pregnancy, it was carried out in Al-Batool Hospital during the month of February 2021in Diyala/ Iraq, on 30 pregnant women in 3rd trimester (27.04 ± 2.130 years), as well as a control group of 30 non-pregnant women, where serum electrolyte are measured for each group. When compared to the control group, the results of the current study demonstrate a significant decrease in serum calcium, potassium, and sodium in the third trimester pregnant group, while there are no significant differences in chloride and phosphate levels between two groups. This research found a significant difference in serum electrolytes concentrations in last stages of pregnancy women, particularly for potassium and calcium, Electrolytes testing may be included as one of the standard and universal tests conducted during pregnancy to prevent fetal-maternal morbidity and mortality due to electrolytes.