New Moms at Risk of Developing High Blood Pressure After Childbirth, Study Finds

Undiagnosed high blood pressure can have serious health consequences, and the condition may be more common in people post-pregnancy than previously thought.

A recent study found that the time frame for developing high blood pressure after childbirth extends beyond the typical six weeks of postpartum care. The researchers were surprised to see how common the condition was up to a year after giving birth.

“Not only was this number higher than we expected, but this time period falls out of postpartum care, which could have implications where these diagnoses are missed,” says Samantha Parker, PhD, an assistant professor of epidemiology at the Boston University School of Public Health, who led the observational study.

High blood pressure during pregnancy can cause low birth weight and preterm delivery, and can increase a pregnant person’s risk for heart attack and stroke. In people who are not pregnant, including those who have recently given birth, undetected high blood pressure can cause a host of issues, including heart attack, stroke, narrowed arteries, heart failure, kidney disease and failure, vision loss, and sexual dysfunction, according to the American Heart Association (AHA).

Higher Risk Among Moms Over 35, Black Women, and Those Who Smoked

In the study, which was published in November 2022 in the AHA journal Hypertension, researchers analyzed nearly 2,500 medical records of deliveries from 2016 to 2018 among people with no history of chronic hypertension. About 1 in 5 of those who developed high blood pressure after giving birth did so after more than six weeks after the birth. Just over 1 in 10 developed high blood pressure within the first year postpartum, long after typical postpartum care ends.

“These are people who, in our current model, would never be asked to be monitored for hypertension because they don’t fall into a high-risk group,” says Dr. Parker.

The study found that hypertension within the first year of pregnancy was more common in mothers age 35 and older and those who smoked. About 36 percent of Black mothers in the study developed high blood pressure postpartum, which aligns with previous research finding that Black Americans have the highest high blood pressure rates in the United States.

Those who delivered via cesarean section were also more likely to develop high blood pressure after birth. However, this may have been due to factors that warranted a C-section delivery rather than the surgery itself.

“C-sections are more common in people who are overweight or have diabetes, or in cases where there is fetal growth restriction, all of which can put you at risk for high blood pressure,” says Elizabeth Langen, MD, the co-director of the cardio-obstetrics program at University of Michigan Health in Ann Arbor, who was not involved in the research.

Over-the-counter pain medications like NSAIDs — including anti-inflammatory drugs such as ibuprofen (Motrin, Advil) and naproxen (Aleve, Naprosyn), which are commonly used to manage pain after a C-section — have also been reported to temporarily increase risk for high blood pressure.

According to UpToDate, NSAIDs can raise blood pressure in anyone, and the U.S. Food and Drug Administration advises against taking NSAIDs after 20 weeks of pregnancy. Acetaminophen (Tylenol) is widely accepted as safe to take during pregnancy. Although a statement published in 2021 in Nature Reviews Endocrinology warned that acetaminophen may cause birth defects if taken during pregnancy, those risks do not apply once the baby is delivered.

Pregnancy Causes Major Changes in the Body

More research is needed to better understand the long-term effects of pregnancy in people who are not currently considered high risk for conditions such as hypertension, notes Dr. Langen.

“We know there are a lot of adaptations that happen during pregnancy, including in the cardiovascular system, but we don’t yet understand the long-term consequences of these changes for people who don’t have other risks like preeclampsia,” she explains.

During pregnancy, the amount of blood circulating through the body increases by 30 to 50 percent. This means the heart needs to pump more blood each minute, causing the heart rate to increase. Labor also strains the cardiovascular system, especially during pushing, when the body undergoes abrupt changes in blood flow and pressure, according to the Mayo Clinic.

The Need for Postpartum Moms to Continue Getting Care

Langen notes that pregnancy is a time when people have more access to healthcare and see providers much more frequently. “It’s a good opportunity to recognize risk factors, like high blood pressure, so we can reduce the risk of heart disease later on in life.”

While seeking care after the six-week postpartum period isn’t possible for everyone, especially those with limited or no insurance, Langen said the new study highlights the need to seek primary care following the postpartum period. Home blood pressure monitors could be one simple way that new moms can monitor their blood pressure even after postpartum care ends.

Previous research has shown that pregnancy-related hypertension is on the rise in the United States.

A study published in May 2022 in the Journal of the American Heart Association included data from more than 51 million births in the United States between 2007 and 2019. Those researchers found that pregnancy-related high blood pressure disorders doubled during that time.

“We know that people who have hypertension during pregnancy are at a higher risk for cardiovascular disease later on, but we don’t know much about what hypertension that develops after pregnancy can lead to in the long term,” Parker says, noting that the research shows pregnancy-related morbidity could extend far beyond the initial six weeks post-birth.

The rise of virtual and at-home healthcare could provide a great opportunity for blood pressure monitoring beyond the six-week postpartum period, notes Parker.

“These findings emphasize the point that healthcare for women cannot be limited to the 40 weeks of pregnancy,” says Langen. “Once the baby is born, we need to continue to advocate for women to have access to healthcare and teach them how to monitor their blood pressure at home.”