Early life environment associated with higher risk of hypertension in children

Where a mother lives and the temperature outside while she is pregnant, among other environmental factors, can impact whether her child is prehypertensive or hypertensive during childhood, according to a new study published in the Journal of the American College of Cardiology.

Exposure to negative lifestyle factors in pregnancy, such as obesity, physical inactivity, poor diet, and alcohol and tobacco consumption have long been established as heart disease risk factors for mothers. Only in recent years have studies begun to link these risk factors to prehypertensive status in children and their likelihood of developing hypertension, or high blood pressure, later in life.

The study included data from a total of 1,277 mother-child pairs from the Human Early-Life Exposome (HELIX) project, which pooled data of six European birth cohorts from the United Kingdom, France, Spain, Lithuania, Norway, and Greece. The selected children were between the ages of 6 to 11 years old, had stored blood and urine samples available and had no prior health problems. At the time of the examination, 10 percent of the children could be classified as prehypertensive or hypertensive, according to the study abstract.

Researchers evaluated a total of 89 prenatal maternal exposures and 128 postnatal child exposures. Of these, four broader environmental factors were determined to influence blood pressure status in children, built environment or where the mother was living during pregnancy, outdoor temperature, fish intake, and exposure to chemicals.

Mothers who lived in a walkable environment with access to green spaces, shops, restaurants, and public transportation during pregnancy were associated with normal blood pressure in their children. Alternatively, the mothers who did not live in an urban or highly walkable environment had higher blood pressure. The researchers hypothesized that the lower blood pressure that resulted from living in an urban setting was due to the higher amount of physical activity during pregnancy.

Exposure to a higher outdoor temperature during the time of the blood pressure assessment was associated with lower diastolic blood pressure in children. Outdoor temperature has been proven in previous studies to be a known environmental factor to affect blood pressure in both adults and children.

Both low and high fish intake during pregnancy were associated with an increase in blood pressure in children. While the omega-3 fatty acids found in fish are beneficial for overall cardiovascular health, fish contaminated by chemicals or metals could reduce any positive effects of omega-3 fatty acids, researchers said.

Exposure to bisphenol-A (BPA) concentrations, a chemical found in various consumer plastics, during pregnancy resulted in higher blood pressure in children, as did exposure to perfluorooctanoate (PFOA) concentrations, a chemical found in cosmetics, household cleaners, or clothing. Children who had been exposed to copper during childhood also had a higher blood pressure.

This study has several limitations, including exposure misclassification and the small sample size given the large number of exposures investigated. While the present study remains at risk of false positives or negatives, it highlights that environmental exposures early in life have potentially important effects on blood pressure in children.