Study on the change of PR interval shortening in ECG examination in different periods of pregnancy

Objective\r\nTo research the change of PR interval shortening in ECG examination in different periods of pregnancy.\r\n\r\n\r\nMethods\r\nFrom March 2016 to August 2016, 616 pregnant women who underwent maternity examinations in the Women and Children\u0027s Hospital of Ningbo were selected in this study.According to the different gestational periods, they were divided into the early pregnancy group (198 cases), the mid-pregnancy group (232 cases) and the late pregnancy group (186 cases). And another 241 non-pregnant women who underwent health examination in our hospital during the same period were selected as controls.All pregnant and non-pregnant women were examined by electrocardiogram, and the results of electrocardiogram were analyzed.The average heart rate, the average PR interval and the shortened ratio of PR interval were compared between the two groups of women and women with different pregnancy periods, and the short PR interval distribution of women in different pregnancy periods was observed.\r\n\r\n\r\nResults\r\nThe average heart rate level, PR interval and PR interval shortening ratio of pregnant women and non-pregnant women were (76.55±7.81)times/min, (0.096±0.008)s, 12.66% and (72.56±6.49)times/min, (0.138±0.014)s, 4.98%, respectively.The average heart rate and the shortening ratio of PR interval in pregnant women were significantly higher than those in non-pregnant women, while the average PR interval in pregnant women was significantly lower than that in non-pregnant women, the differences were statistically significant (t=7.565, χ2=10.879, t=52.672, all P\u003c0.05). With the increase of pregnancy cycle, the shorter the average heart rate and PR interval of pregnant women, the shorter the average PR interval.The average heart rate, PR interval and PR interval shortening ratio in the early pregnancy group, the mid-pregnancy group and the late pregnancy group were (75.41±6.65)times/min, (0.103±0.010)s, 8.59% and (77.03±7.12)times/min, (0.095±0.009)s, 11.21% and (79.74±8.43)times/min, (0.088±0.008)s, 18.82%, respectively.There were statistically significant differences among the three groups(t=16.720, 116.440, χ2=9.791, all P\u003c0.05).\r\n\r\n\r\nConclusion\r\nPregnancy women are prone to have shorten PR interval, and its incidence increases with the increase of pregnancy cycle, but in most cases belongs to benign electrophysiological changes, and the prognosis is good without special treatment.It is of great significance for clinical diagnosis and treatment to reduce the outcome of bad pregnancy by observing the shortening of the PR interval of electrocardiogram during the pregnancy.\r\n\r\n\r\nKey words: \r\nElectrocardiography; Pregnant women; Heart rate; PR interval shortening; Sinus agitation; Pregnancy outcome