Detection of Midpregnancy Fall in Blood Pressure by Out-of-Office Monitoring

Abstract

Silva et al 1 have demonstrated the absence of a midpregnancy fall in diastolic blood pressure (BP) in women with a low educational level. Their previous articles also showed that maternal socioeconomic status is associated with a risk of gestational hypertension and preeclampsia. 2 However, they did not demonstrate a midpregnancy fall in systolic BP in all of the educational subgroups. This might be attributable to few measurement points being obtained during pregnancy or to some other confounding factors.Ambulatory BP measurement is one way to resolve inferior results from isolated BP measurements. Hermida et al 3 measured ambulatory BP in 403 pregnant women for 48 consecutive hours every 4 weeks from the first obstetric visit until delivery. They found that BP steadily decreased up to 20 weeks of pregnancy and increased up to the day of delivery. Conversely, in women with gestational hypertension and preeclampsia, BP remained stable until the 22nd week of gestation and then linearly increased for the remainder of the pregnancy.The American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association scientific statements indicate that home BP monitoring might overcome many of the limitations of traditional office BP measurements, and it is less expensive and easier to perform than ambulatory BP monitoring. 4 Home BP measurements are theoretically ideal for monitoring changes in BP during pregnancy, because home measurement is the optimal way to record multiple readings taken at the same time of day over prolonged periods. 4 We recently conducted a prospective observational study (Babies and Their Parents' Longitudinal Observation in Suzuki Memorial Hospital on Intrauterine Period Study), in which we averaged 100 BP measurement points during pregnancy in 101 normotensive pregnant women. 5 We found that BP during pregnancy is associated with both seasonal effects and gestational age. We found that the gestational week when BP reached the nadir differed according to the season in which delivery was predicted.As Silva et al 1 commented in their Discussion, the absence of a midpregnancy fall in BP is reportedly associated with preeclampsia, according to a population study, and may be a sign of latent endothelial dysfunction. However, the amplitude of the fall in midpregnancy BP seems smaller than that of circadian, daily, and seasonal BP variations. Home BP measurement would be a good tool with which to detect such small changes in BP during early pregnancy.

Response to Metoki

“…Consistent with previous studies showing that home BP fell from the first trimester to the second trimester and then continued to increase until the time of delivery, 3 and that pregnant women who delivered in winter tended to have higher home BPs than those who delivered in summer, 4 we confirmed the mid-pregnancy fall in BP and the seasonal trend in BP changes during pregnancy even if BPs are measured at the clinic. We hope that our study will inspire researchers to further examine the effects of the mid-pregnancy fall in BP and the seasonal trend in BP changes during pregnancy on predicting the risk of PIH.…”

“…Because pregnant women with low BP at week 20 had less risk of PIH, 2 even if these women had high BP at week 16, a mid-pregnancy fall in BP is thought to be inversely correlated with the occurrence of PIH. As suggested by Metoki et al, 3 endothelial function may contribute to the relationship between the mid-pregnancy fall in BP and the occurrence of PIH. In addition, we assessed the seasonal trend in BP changes during pregnancy.…”

Blood Pressure Variation Throughout Pregnancy According to Early Gestational BMI: A Brazilian Cohort

“…The maternal cardiovascular system undergoes progressive adaptations throughout pregnancy, including decreased vascular resistance, increased blood volume, and other metabolic changes 1 . Although the effects of these changes on systemic blood pressure (BP) have been described in many studies, there is no consensus on its normal variation in uncomplicated pregnancies 2 , 3 .…”

“…The etiology of HDP is not clear; however, there are several risk factors associated with their occurrence, such as body mass index (BMI) 6 . As the prevalence of obesity increases in women of reproductive age 7 , BMI [weight (kg)/stature 2 (m 2 )] and its associated complications represent a relevant public health matter. Maternal obesity is a significant risk factor for morbidity and mortality for both mother and fetus 8 .…”