Study finds link between pregnancy mineral levels and lower blood pressure in midlife

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 Prevention | Lifestyle 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. 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."

Mingyu Zhang, Ph.D., M.H.S., lead study author, epidemiologist and instructor in medicine at Beth Israel Deaconess Medical Center and Harvard Medical School, Boston

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.

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.