Medical text books are based on data that is now over forty years old. New research from researchers at The University of Oxford, and published in BMC Medicine, includes much more recent data. The new findings show that changes to women’s blood pressure and heart rate during pregnancy are not as striking as previously thought.
Traditionally, medical text books have taught students that blood pressure drops by 10-15mmHg during the middle of pregnancy. These text books are based on old data and quite small numbers of pregnant women. This newer and much larger analysis shows that the lower diastolic blood pressures seen mid-pregnancy are on average just 1-2 mmHg lower than the earliest measurements that were taken in about week 10. This is much less of a drop than suggested in the text books. The analysis also shows that, on average, systolic blood pressure rises very slightly through pregnancy.
Read more (University of Oxford website)