Controlling Blood Pressure After Pregnancy Leads to Cardiovascular Benefits

The earlier a woman gets her blood pressure controlled after giving birth, the quicker the blood pressure will return to normal levels and the healthier the heart will be, a new study found.

The study—presented November 11, 2023, at the American Heart Association’s Scientific Sessions 2023 (AHA) in Philadelphia, Pennsylvania as a late breaker—examined postpartum women who had high blood pressure during their pregnancy. The study found the women had long-term blood pressure and cardiovascular benefits if their blood pressure was controlled for the first few weeks after delivery.

“The heart undergoes significant changes during any pregnancy to cope with the increased circulatory demands of the growing baby, and these changes are much more profound during a hypertensive pregnancy, because of the increased stress of the pregnancy,” the lead investigator,

Paul Leeson, MB, BChir, PhD, at the University of Oxford in the United Kingdom, told the American Health Association in a press release. “Women who have had uncontrolled high blood pressure during pregnancy are at significantly greater risk of complications with their heart longer term.

Leeson continued by stating a third of woman who give birth develop hypertension within 10 years of pregnancy—doubling their risk of early heart attack or stroke.

Leeson and colleagues conducted a prospective, randomized trial in the United Kingdom to see the effects of improving blood pressure control immediately following pregnancy. The participant sample included 220 new mothers who had high blood pressure during pregnancy and still needed medicine to control the blood pressure levels. Many of the women were white (80%), with an average age of 33 years. About 65% of the mothers had completed their first pregnancy, 30% had completed their second pregnancy, and 5% had completed their third pregnancy.

Half of the mothers were randomly assigned to a group that received wireless blood pressure monitors that were connected via an app. The investigators wanted daily pressure readings, so to avoid margins of human error, the blood pressure monitors automatically sent over readings to the app via Bluetooth.

On the app, participants received automated prompts, either repeating a blood pressure reading or prompting the participant to call their doctor in the trial if their blood pressure level was out of the healthy range. If the participant had to call the doctor, they were told via phone or video call how much to adjust the medication dose to ensure their blood pressure remained below 140/90 mm Hg.

The second half of mothers received the usual UK postpartum care, consisting of an office visit with a physician or midwife 5 – 10 days of delivery and another visit 6 – 8 weeks after giving birth.

“The trial suggests the timing of this second appointment may miss a critical window for early blood pressure optimization,” Leeson said in the press release. “While this visit includes a blood pressure examination and participants are likely to be on blood pressure medication until their blood pressure is back in a normal range, their blood pressure will not be as carefully monitored, and medication will not be as tightly adjusted as in the intervention group of the trial.”

The intervention group had more improved blood pressure levels 9 months after delivery—the average blood pressure was 126/mm Hg. Mothers in this group had a median treatment length of anti-hypertensive medication of 39 days, although 70% of women no longer needed high blood pressure medicine by roughly 6 weeks after giving birth. Blood pressure levels continued lowering 8 to 9 months after ending the medication. Following intervention, fewer women needed to return to the hospital in the first 3 weeks because of high blood pressure.

Meanwhile, the mothers who received usual care had mean blood pressure levels of 131/86 mm—thus higher than the intervention group.

Moreover, 90% of mothers agreed to have cardiac magnetic resonance imaging and echocardiography at 9 months postpartum. Here, the investigators found women who had stronger blood pressure control after delivery demonstrated better improvements in the structure and function of the heart, compared to women who simply received usual UK care.

Leeson concluded by saying he was surprised by the amount and the consistency of the blood pressure levels reducing in mothers receiving the intervention. He added how blood levels improved within the first or second week after pregnancy, and the blood pressure continued improving after medication was stopped.

“A 5-10 mm Hg reduction in blood pressure is typically associated with a 20% reduction in longer-term cardiovascular risk,” Leeson said. “If the reduction in blood pressure we observed at nine months is sustained long-term, this could slow progression to needing treatment for hypertension by an average of up to a decade.”

References

^{Improving Blood Pressure Control After Pregnancy Had Long-Term Cardiovascular Benefits. American Heart Association. https://newsroom.heart.org/news/improving-blood-pressure-control-after-pregnancy-had-long-term-cardiovascular-benefits. Presented at American Heart Association’s Scientific Sessions 2023, November 12, 2023.}