Critical six-week window to reset blood pressure after giving birth

Lowering a hypertensive mother’s blood pressure within six weeks after giving birth could significantly cut their future risk of a heart attack or stroke, according to research we've funded and published in Hypertension.

The University of Oxford researchers also found that giving women blood pressure monitors and personalised advice led to lower blood pressure in this critical six-week window, and in the four years that followed. 

Around one in ten women develop hypertension (high blood pressure) during pregnancy. This significantly increases their risk of long-term high blood pressure, which can lead to a heart attack or stroke.  

Elevated blood pressure after pregnancy can cause ‘remodelling’ of the mother’s heart and blood vessels, and so the team were interested in whether controlling high blood pressure in the six weeks after birth could help the mother’s heart and blood vessels ‘recover’ after a pregnancy complicated by high blood pressure. Acting during this period could thereby ‘reset’ a woman’s blood pressure to pre-pregnancy levels and prevent harmful changes to her heart and circulatory system from becoming permanent.

Home blood pressure monitoring

In an earlier trial, the researchers investigated whether new mothers who monitored their blood pressure at home every day for six weeks after a hypertensive pregnancy would have bigger reductions in their blood pressure, compared to new mothers who received usual care. 

They found that women who were given a device to monitor their blood pressure daily and received personalised advice from doctors on adjusting their blood pressure lowering medication in response to the readings, a process called self-management, had lower blood pressure at six weeks and six months after birth.

Long term changes 

Now, four years later, the team have followed up 61 of the women (31 received usual care and 30 were randomized to self-management) to assess the longer-term impact of monitoring their blood pressure. They found that diastolic blood pressure – your blood pressure reading at the point your heart relaxes between beats – was on average 6.8 mmHg lower in women who had self-managed than those who received usual care. 

This sustained reduction in blood pressure remained even though the women had stopped taking their blood pressure lowering medication several years earlier.

The researchers estimate that a decrease of 6.8mmHg would reduce the subsequent risk of developing heart and circulatory conditions in future by more than 30 per cent.

Supporting new mothers

Dr Sonya Babu-Narayan, our Associate Medical Director and Consultant Cardiologist, said: “High blood pressure affects one in 10 pregnancies and increases the risk that a woman will develop cardiovascular disease during her lifetime. But the opportunity to tackle this risk factor in new mothers is often missed after the birth of their child.

“This research illustrates the importance of providing the right care and support for women in the early weeks and months after giving birth to help them keep their blood pressure in a healthy range. The results are very promising and could lead to important changes in how we treat women who have had high blood pressure during pregnancy.”

Find out more about our risk factor research