Study question: Are oxygen uptake and the pleiotropic hormone relaxin associated with the mechanism of blood pressure during pregnancy?
Summary answer: Diastolic blood pressure, but not systolic, displayed a significant reduction with increased oxygen uptake and increased serum relaxin levels.
What is known already: Data showing an inverse association between serum relaxin concentrations and either blood pressure during pregnancy or hypertension has been suggested. An association of oxygen uptake with blood pressure during pregnancy has not been previously reported.
Study design, size, duration: A prospective cohort study of 520 pregnant women in early pregnancy from March 2001 to June 2003.
Participants/materials, setting, methods: Baseline data collection in early pregnancy included submaximal cycle ergometer test and blood sampling. The participants were followed repeatedly throughout pregnancy with blood pressure measurements at Maternal Health Centers.
Main results and the role of chance: Oxygen uptake, serum relaxin concentrations, number of previous deliveries, and cigarette smoking were demonstrated to be negatively associated with, and height positively associated with (all independently) average diastolic blood pressure (p<0.0001) by multiple regression analysis. Similarly, number of previous deliveries, and cigarette smoking were negatively associated with, and height positively associated with, (all independently) systolic blood pressure (p=<0.0001)
Limitations, reasons for caution: The blood pressure was measured to the nearest 5 mmHg instead of the recommended 2 mmHg, which probably reduced the sensitivity to show only the strongest association to blood pressure.
Wider implications of the findings: The results give clinical implication for non-pharmacological approach of lowering of blood pressure during pregnancy in a public health perspective.
Blood pressure, pregnancy, oxygen uptake, physical exercise, relaxin.