University of Bristol | July 2018 | High blood pressure in pregnancy linked to mother’s heart function
Research carried out by scientists at Imperial College London, the Universities of Cambridge and Bristol indicates that high blood pressure in pregnancy may be due to the heart pumping less blood with each beat.
The researchers followed over 200 women prior to and during their pregnancies. Before becoming pregnant all the participants were assessed to test their heart function and blood circulation. They compared the 15 women who developed pre-eclampsia during pregnancy with women who had a healthy pregnancy.
The results revealed that although the women’s heart and blood pressure were still in the healthy range, their hearts pumped 16 per cent less blood per minute than the women who had healthy pregnancies, and their blood vessels were 17 per cent more resistant to blood flow. This caused their blood pressure to be slightly higher, but still normal.
These findings indicate that expectant mothers who develop high blood pressure (pre-eclampsia), or fetal growth restriction (where a baby’s growth slows or stops before birth), may have differences in their blood circulation (via University of Bristol).
Preeclampsia and fetal growth restriction during pregnancy are associated with increased risk of maternal cardiovascular disease later in life. It is unclear whether this association is causal or driven by similar antecedent risk factors. Clarification requires recruitment before conception which is methodologically difficult with high attrition rates and loss of outcome numbers to nonconception/miscarriage. Few prospective studies have, therefore, been adequately powered to address these questions. We recruited 530 healthy women (mean age: 35.0 years) intending to conceive and assessed cardiac output, cardiac index, stroke volume, total peripheral resistance, mean arterial pressure, and heart rate before pregnancy. Participants were followed to completion of subsequent pregnancy with repeat longitudinal assessments. Of 356 spontaneously conceived pregnancies, 15 were affected by preeclampsia and fetal growth restriction. Women who subsequently developed preeclampsia/fetal growth restriction had lower preconception cardiac output and cardiac index while mean arterial pressure and total peripheral resistance were higher. Longitudinal trajectories for cardiac output and total peripheral resistance were similar between affected and healthy pregnancies, but the former group showed a more exaggerated fall in mean arterial pressure in the first trimester, followed by a steeper rise and a steeper fall to postpartum values. Significant relationships were observed between cardiac output, total peripheral resistance, and mean arterial pressure and gestational epoch. We conclude that in healthy women, an altered prepregnancy hemodynamic phenotype is associated with the subsequent development of preeclampsia/fetal growth restriction.