Women in the highest quintile for pre-conception calcium intakes were 24% less likely to experience hypertensive disorders during pregnancy compared with those in the lowest quintile, a study suggests.

For zinc, participants in the highest quartile for pre-conception intakes were 38% less likely to experience hypertensive disorders during pregnancy than those with the lowest intakes. 

The findings underscore the importance of getting the right nutrition before conceiving, not just during pregnancy itself, the scientists explained.

“Our findings underscore the significance of preconception dietary intake of calcium and zinc in potentially reducing the risk of hypertensive disorders of pregnancy,” said Dr Liping Lu, who conducted the research as a postdoctoral research scientist at Columbia University and is now an assistant professor at Indiana’s Ball State University.

“Higher intakes of zinc and calcium before conception, derived from diet and supplements, are both associated with a lower risk of hypertensive disorders during pregnancy.”

High blood pressure: A common disorder of pregnancy

Hypertension, or high blood pressure, is one of the most common disorders of pregnancy and can harm both the pregnant person and the developing foetus.

Because of the potential adverse effects of antihypertensive medications during pregnancy, research has explored how to prevent dangerous hypertension-related disorders – such as pre-eclampsia – through modifiable factors like nutrition.

While many people begin focusing on nutrition after becoming pregnant, nutritional status before conception is just as important, since it can often take time for the body to correct deficiencies, warned the scientists.

“The health of women during the preconception period is strongly linked to the pregnancy outcome,” Lu said. “Adequate nutrient or mineral stores in the body prior to conception can ensure optimal nutrient status for conception and support the early stages of foetal growth and development.”

Higher calcium and zinc intakes linked to lower likelihood of hypertension

The team conducted two separate studies using data from more than 7,700 pregnant women across the US who provided information about their health and diet through participation in the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be.

One study focused on calcium; the other, zinc. The researchers analysed the association between pre-conception intakes of each mineral and rates of hypertensive disorders of pregnancy after accounting for demographics, lifestyle, and health factors that are linked with a risk of hypertension.

The results, which were presented earlier this month at NUTRITION 2024, the annual meeting of the American Society for Nutrition, showed that people in the highest quintile for pre-conception calcium intake were 24% less likely to experience hypertensive disorders during pregnancy compared with those in the lowest quintile.

For zinc, participants were divided into quartiles and those with the highest pre-conception intakes were 38% less likely to experience hypertensive disorders during pregnancy than those with the lowest intakes. 

Calcium and zinc recommendations vary between countries

As these were observational studies, Lu admitted that the results do not prove causation. However, they align with findings from other studies that have linked higher intakes of both minerals with a lower risk of hypertension-related diseases outside of pregnancy.

Calcium and zinc are both known to play important roles in metabolic processes related to maintaining the health of blood vessels, providing a plausible biological explanation for their role in the prevention of blood pressure disorders.

Maternal calcium needs are no different to those of non-pregnant women in the same age group, as calcium uptake becomes more efficient during this period. Recommended calcium intakes for pregnant women vary between countries, from 900 to 1,200 mg/day. A dietary intake of 1,200 mg/day of calcium is recommended by the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO).

Zinc contributes to normal growth and development during pregnancy and, as such, a higher intake is recommended during this time, according to the European Food Safety Authority (EFSA).

“Additional PRIs [population reference intakes] for pregnancy and lactation were estimated to be 1.6 mg/day and 2.9 mg/day, respectively,” it said.