Preeclampsia: What It Is, Symptoms, Risk Factors, Treatment & Prevention

Normal Blood Pressure In Pregnancy May Still Signal Future Hypertension Risk

A new study has found that some women who maintain blood pressure levels within the clinically normal range during pregnancy may still be at significantly higher risk of developing high blood pressure within five years of giving birth—especially if their blood pressure does not drop during the second trimester, as is typical in healthy pregnancies.

The research, published in the Journal of the American College of Cardiology: Advances, shows that about 12% of pregnant women fall into this overlooked risk category.

These women would not be flagged under current medical guidelines, as their blood pressure remains below the standard thresholds for concern. Yet, their risk of developing chronic hypertension after pregnancy was found to be nearly five times higher than women whose blood pressure followed the expected healthy pattern.

What the Study Found

Researchers followed 854 women from pregnancy through five years postpartum, using data from the MADRES cohort—a long-term health study involving primarily low-income Hispanic women in Los Angeles.

The team tracked blood pressure measurements, along with demographic, lifestyle, and health data collected periodically during pregnancy and annually after birth.

They identified three key blood pressure patterns:

Low and steady blood pressure throughout pregnancy (80.2% of women)

High early blood pressure that dipped in mid-pregnancy and then rose again (7.4%)

Slightly elevated but stable blood pressure with no mid-pregnancy dip (12.4%)

Women in the second group—those with high early pregnancy blood pressure and a second-trimester dip—were already known to be high-risk. Many of them developed complications such as preeclampsia or gestational hypertension during pregnancy. They faced a 5.44 times higher risk of developing hypertension in the years after giving birth.

But the surprising discovery was in the third group, whose blood pressure stayed slightly elevated yet still within normal limits, and did not drop in mid-pregnancy. These women had no typical warning signs during pregnancy, but their risk of future hypertension was almost as high—4.91 times greater than the group with consistently low blood pressure.

A Missed Warning Sign?

"This group of women would not be identified as high-risk using today's clinical criteria," said Dr. Shohreh Farzan, senior author and associate professor at USC's Keck School of Medicine. "Their blood pressure looked normal on paper, but the pattern of not having that expected mid-pregnancy drop was the red flag."

This finding is important because current blood pressure guidelines during pregnancy focus mainly on identifying hypertension or dangerously high readings. They don't account for patterns of change—particularly the normal physiological drop that typically occurs in the second trimester due to hormonal shifts and increased blood flow.

Dr. Zhongzheng (Jason) Niu, the study's lead author, noted that this is one of the first major studies to look at blood pressure risk between pregnancy and menopause—a critical but under-researched time in women's health.

"This period has been a blind spot in cardiovascular research," Niu said. "Our work helps fill that gap and shows that early signs of trouble can appear much earlier than previously thought."

Clinical and Public Health Implications

The study suggests that tracking blood pressure trends—not just single readings—during pregnancy could help doctors identify women at risk for long-term heart issues, even if their readings never cross into the "high" category. This could lead to early interventions, such as closer monitoring after birth, lifestyle counseling, or preventive treatments.

Given the growing awareness of women's heart health, and the American Heart Association's efforts to refine its guidelines, this research may lead to new standards for prenatal care that could help prevent chronic hypertension and related cardiovascular problems later in life.

The team is also investigating whether environmental exposures—such as air pollution or chemicals like PFAS—might contribute to these unusual blood pressure patterns. If so, it could add an important public health layer to future pregnancy care and disease prevention.

Review and Analysis

This study provides an important message: "normal" blood pressure during pregnancy isn't always a sign of low risk. By focusing on blood pressure patterns—especially the expected mid-pregnancy dip—doctors may be able to detect a group of women who are quietly at higher risk for developing long-term hypertension.

The findings are especially significant for women of color and those from underserved communities, who are more likely to face healthcare barriers and may already be at higher risk of cardiovascular disease.

As simple tools like blood pressure tracking apps become more widely available, it may soon be possible for expectant mothers and clinicians to monitor these patterns more closely, empowering more personalized and proactive care.

In short, this research challenges the assumption that "normal" always means "safe"—and provides a powerful opportunity to detect and prevent disease earlier in women's lives.

If you care about blood pressure, please read studies about blood pressure drug that may increase risk of sudden cardiac arrest, and these teas could help reduce high blood pressure.

For more information about health, please see recent studies about nutrient that could strongly lower high blood pressure, and results showing this novel antioxidant may help reverse blood vessels aging by 20 years.

The research findings can be found in JACC: Advances.

Copyright © 2025 Knowridge Science Report. All rights reserved.

Pregnancy Blood Pressure Patterns May Predict Future Hypertension Risk

New research suggests that tracking blood pressure changes during pregnancy could help predict a woman's risk of developing high blood pressure (hypertension) in the years after giving birth.

The study found that women whose blood pressure remained stable but did not dip in mid-pregnancy had a significantly higher chance of developing hypertension later—despite having blood pressure levels considered normal during pregnancy.

The research, published in the Journal of the American College of Cardiology: Advances, followed 854 women from pregnancy through five years postpartum.

Researchers mapped their blood pressure changes and found three main patterns:

Low and stable blood pressure (80.2%) – These women had no significant changes and were at the lowest risk of future hypertension.

High blood pressure with a mid-pregnancy drop (7.4%) – Their blood pressure started high, dropped in the second trimester, then rose again. These women were already considered high-risk due to conditions like preeclampsia.

Slightly elevated blood pressure with no mid-pregnancy drop (12.4%) – These women had blood pressure in the normal range but without the usual second-trimester dip. They were 4.91 times more likely to develop hypertension within five years after childbirth compared to the low-blood-pressure group.

The women in the third group would not usually be flagged as high-risk since their blood pressure remained within normal limits.

However, their increased risk suggests that simply staying within clinical guidelines isn't enough—monitoring patterns over time may be key to early detection and prevention of heart disease.

"This group of women wouldn't be identified as having a higher risk under current guidelines," said Dr. Shohreh Farzan, the study's senior author from the Keck School of Medicine at USC. "But tracking blood pressure changes during pregnancy could help us find and support them before problems arise."

A critical time for women's heart health

The study highlights a gap in medical research: the period between pregnancy and menopause. While heart disease is a leading cause of death in women, many pregnancy-related risk factors go unnoticed until much later in life.

The American Heart Association and the American College of Obstetricians and Gynecologists are now paying more attention to these long-term risks.

Lead author Dr. Zhongzheng (Jason) Niu, an assistant professor at the University at Buffalo, emphasized that simple changes in clinical practice—such as monitoring blood pressure patterns instead of just single readings—could help identify at-risk women early. Future research will explore whether environmental factors, like air pollution and chemicals, influence these blood pressure patterns.

What can be done?

Doctors may need to track blood pressure trends more closely during pregnancy and follow up with women whose pressure does not dip in the second trimester. The American Heart Association may also consider updating its guidelines for pregnancy-related hypertension risk.

Understanding these patterns could lead to earlier interventions, helping more women avoid high blood pressure and heart disease in the years after giving birth.

Vitamin And Mineral Levels In Pregnancy Linked To Blood Pressure

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Women with higher levels of essential minerals circulating in their blood during pregnancy, particularly copper and manganese, along with vitamin B12, had a lower risk of developing high blood pressure in middle age, about 20 years later, according to research presented at the American Heart Association's Epidemiology and PreventionLifestyle and Cardiometabolic Health Scientific Sessions 2025. The meeting will be held in New Orleans, March 6-9, 2025, and offers the latest science on population-based health and wellness and implications for lifestyle. According to the study authors, it is the first to explore the associations of pregnancy metal levels with women's midlife blood pressure and hypertension risk, and the full manuscript is simultaneously published today in the American Heart Association's peer-reviewed journal Hypertension.

Manganese, selenium, magnesium and copper are among the essential metals important for a healthy body because their anti-oxidation and anti-inflammatory properties may help protect against cardiovascular disease. Previous research has found that higher levels of manganese were associated with a lower risk of preeclampsia (high blood pressure during pregnancy). However, it is not known whether higher levels of essential metals during pregnancy may influence the risk of developing high blood pressure later in life. Additionally, chronic exposure to the non-essential metals lead, cadmium and arsenic is associated with an increased risk of cardiovascular disease, according to the Association's 2023 scientific statement "Contaminant Metals as Cardiovascular Risk Factors."

"People are constantly exposed to heavy metals and trace elements, and much research has shown that exposure to those metals and elements may have an impact on cardiovascular health, especially hypertension," said lead study author Mingyu Zhang, Ph.D., M.H.S., an epidemiologist and instructor in medicine at Beth Israel Deaconess Medical Center and Harvard Medical School, both in Boston. "In our study, we wanted to examine how levels of essential metals and elements during pregnancy may affect blood pressure and hypertension risk in midlife."

The researchers analyzed data from Project Viva, an ongoing, long-term study that began in 1999 of women and their children who live in eastern Massachusetts. Nearly 500 women enrolled in the study during early pregnancy, between 1999 and 2002. Researchers measured concentrations of non-essential metals (arsenic, barium, cadmium, cesium, mercury and lead), essential minerals (copper, magnesium, manganese, selenium and zinc), folate and vitamin B12 in blood samples collected during study enrollment.

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Subscribe for FREE After nearly twenty years of follow-up, researchers conducted a "midlife" study visit between 2017 and 2021 with the same study participants, who were now at a median age of 51.2 years. Researchers measured blood pressure to assess potential associations of individual metals with blood pressure and high blood pressure risk. Participants were categorized as having high blood pressure if blood pressure measures were greater than 130/80 mm Hg or if participants confirmed taking anti-hypertensive medication. In addition, the potential collective effects of all eleven metals and two micronutrients on blood pressure were analyzed.

The study found:

After researchers adjusted for sociodemographic factors, as levels of copper and manganese doubled in the blood during pregnancy, the risk of high blood pressure in midlife was 25% and 20% lower, respectively.

As blood levels of vitamin B12 doubled during pregnancy, women had an average 3.64 mm Hg lower systolic blood pressure and 2.52 mm Hg lower diastolic blood pressure almost two decades later. About 95% of the study participants had vitamin B12 levels within the normal range, the researchers noted.

Blood levels of the mixture of copper, manganese, selenium and zinc were also associated with lower blood pressure in a relationship that increased with dose. Nonessential metals did not have a significant impact on blood pressure.

"Circulating levels of these metals and minerals in blood were measured, however, the sources of exposure, such as food or dietary supplements, were not quantified so these findings should not be interpreted as recommendations," Zhang said. "Optimizing these essential metals, minerals and vitamins, particularly copper, manganese and vitamin B12, during pregnancy may offer protective benefits against hypertension in midlife, an especially critical time period for women's future cardiovascular risk in later life."

"More research including clinical trials is needed to determine the optimal dietary intake of these minerals and micronutrients," he added. The researchers hope to ultimately identify women at high risk for developing high blood pressure later in life and intervene during pregnancy, either with enhanced nutrition or supplements.

 Study details, background and design:

The analysis included 493 women enrolled in Project Viva, a prospective study examining the effects of environmental and lifestyle factors during pregnancy on the short and long-term health of women and their children.

Project Viva enrolled women in early pregnancy between 1999 and 2002. The women had a median age of 32.9 years at enrollment. Participants were followed for 18.1 years, through 2021.

72% of participants self-identified as white women; 11% were self-identified as Black women; and 17% self-identified as Hispanic or Latina, Asian or Pacific Islander, American Indian or Alaskan Native, or selected "Other" race, more than one race or "do not know."

Blood samples were collected at study enrollment and stored in freezers for subsequent analyses. The researchers accessed blood samples and analyzed them for this study in 2018. Folate and vitamin B12 were also measured in blood plasma samples during pregnancy.

Blood pressure was measured in study participants during a "midlife" (median age of 51 years) study visit between 2017 and 2021. During this visit, trained research assistants measured participants' blood pressure up to five times, at one-minute intervals. Blood pressure measurements were then averaged.

The analyses were adjusted for maternal age at study enrollment, pre-pregnancy body mass index, race and ethnicity, education, household income, parity (the number of pregnancies carried to term), use of anti-hypertensive medication, DASH diet score in early pregnancy and multivitamin intake.

The study's limitations include that it was an observational study, meaning other confounding factors that were not measured in the study may have affected the results; the researchers only included a subset of the original Project Viva participants; and there were demographic differences between participants included and excluded. In addition, the researchers did not have measurements for metal levels between delivery and midlife; and participants were predominantly white women who resided in Eastern Massachusetts, which may limit the generalizability of the study's findings.

Reference: Zhang M, Aris IM, Cardenas A, et al. Pregnancy metal mixtures and blood pressure and hypertension in mid-life: A prospective U.S. Cohort study. Hypertension. 2025. Doi: 10.1161/HYPERTENSIONAHA.124.23980

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