259. Casual and home blood pressures measuring for epidemiological study among pregnant women: The TMM BirThree Cohort Study

Abstract

Introduction We previously reported that blood pressure measured at clinic during antenatal care is higher than that measured at home. However, it is still unknown if blood pressure measured not under medical environment but under research environment is different from that measured at home. Hypothesis We hypothesised that blood pressure measured at epidemiological research centres is not much higher than that measured at home. Methods We used the data of 1940 pregnant women who participated in the Tohoku Medical Megabank Birth and Three-Generation Cohort Study (the BirThree Cohort Study), which is conducted in Japan. The BirThree Cohort Study invited pregnant women to our research centres for measuring casual blood pressure twice at each visit. Participants visited the centre once or twice in total during pregnancy. The BirThree Cohort Study also asked pregnant women to measure blood pressure at home in the morning for a week if the participants agreed to measure that. The difference between casual blood pressure and home blood pressure was calculated individuals first, and then the mean of the difference among all participants was calculated on each of the first, second and third trimesters. Results The mean systolic/diastolic casual blood pressures were 100.1 ± 13.1/63.1 ± 9.3 mmHg at the first trimester, 103.6 ± 9.0/61.4 ± 7.6 mmHg at the second trimester, and 105.3 ± 8.9/63.1 ± 7.8 mmHg at the third trimester. As for home blood pressure being available on 895 pregnant women, 108.6 ± 8.9/66.4 ± 8.5 mmHg at the first trimester, 104.0 ± 9.7/61.0 ± 6.9 mmHg at the second trimester, and 106.9 ± 9.8/63.2 ± 7.5 mmHg at the third trimester were observed. The difference between mean casual and home blood pressures at each trimester were: 1.7 ± 11.9 mmHg, −0.3 ± 7.6 mmHg, and −1.7 ± 8.2 mmHg. Discussion Although the number of pregnant women among each trimester was disproportionate, the difference between casual and home blood pressures was small. Even casual blood pressure was tended to be smaller than home blood pressure after the second trimester.