Introduction: During normal gestation, a variety of hemodynamic changes are going to occur. They will influence the condition of heart, which in turn results in changes in electrocardiography. Hence, the present study was designed to study the electrocardiographic changes during different trimesters of pregnancy was compared with nonpregnant controls. Materials and Methods: It is a cross sectional study conducted in the Department of Physiology after institutional clearance and consent from all the participants,150 pregnant women in the age group of 20-35yrs who were attending the OPD of OBG were recruited and divided into 3 subgroupscomprising 50 women in first, second and third trimesters of pregnancy. The control group was comprising of another apparently healthy age matched 50 non-pregnant women.ECG was recorded in all 12 leads and was evaluated for different parameters such as heart rate, P wave, PR interval, QRScomplex, Q wave, T wave, QTc interval, axis deviation, R and S amplitudes and ST segment. Statistical Analysis: The data were expressed as Mean±SD. Z test was used for comparison between control and study groups andwithin the study group. ‘p’ value of 0.05 or less was considered as statistically significant. Result: There was statistically significant decrease in PR interval (p<0.001) in all trimesters of pregnancy when compared to control group. QT intervals did not show significant difference between the control and the study groups or within in the subgroup of study group (p> 0.05). But, QTc interval showed a statistically significant increase 1st, 2nd and 3rd trimester of pregnancy when compared to control group (p< 0.001). Similarly, a statistically significant increase in QTc interval was observed in 2nd and 3rd trimester (p< 0.001, Table-6) of pregnancy when compared to 1st trimester and also in 3rd trimester (p< 0.001) of pregnancy when compared to 2nd trimester. Discussion: Heart rate was increased in 1st, 2nd and 3rd trimesters of pregnancy, a decrease in PR interval was seen all the trimesters of pregnancy, Occurrence of Q wave in leads II and III showed an increase in 2nd and 3rd trimesters of pregnancy, ST segment depression was noticed in 4 subjects in 2nd trimester and 6 in 3rd trimester of pregnancy, QTc interval showed an increase in pregnant women in 1st, 2nd and 3^rd trimesters of pregnancy. Conclusion: This knowledge may be helpful in the prevention of gestational complications associated with an inadequate maternal hemodynamic adaptation.

Keywords: Pregnancy; Hemodynamic Changes; ECG Changes; Trimesters.