Daily serial hemodynamic data during pregnancy and seasonal variation: the BOSHI study.

Although there are some reports that low plasma volume or increased cardiac output is associated with developing preeclampsia, there are few reports of daily serial hemodynamic data during pregnancy. A total of 37,092 home blood pressure (BP) and heart rate (HR) measurements were obtained from 425 normal pregnant women. Heart rate and shock index (SI) gradually increased by gestational week 32 and then decreased, whereas double product (DP) increased linearly during pregnancy. Although systolic BP and DP were consistently and negatively correlated with daily minimum outside temperature, HR and SI were positively correlated with minimum outside temperature in summer.