The number of children with high blood pressure has doubled in the last two decades, an increase that “should raise alarm bells,” according to researchers.

An exhaustive global review published in the medical journalThe Lancet Childhood & Adolescent Healthexamined medical data from 443,914 children aged 18 and younger, and found that between 2000 and 2020, the percentage of children with high blood pressure went from 3% to 6%. That’s an estimated 114 million children.

And 8.2% of children in the study had prehypertension — meaning their blood pressure was high, but not high enough to be diagnosed as high blood pressure.

“The nearly twofold increase in childhood high blood pressure over 20 years should raise alarm bells for healthcare providers and caregivers,” study author Prof. Igor Rudan, Director of the Centre for Global Health Research at The Usher Institute, University of Edinburgh, said in a press release. “But the good news is that we can take steps now, such as improving screening and prevention efforts, to help control high blood pressure in children and reduce the risks of additional health complications in the future.”

The rise in high blood pressure has been linked to a number of factors, like an increase in sedentary lifestyles or environmental pollutants. However, researchers are pointing to one primary cause: “This sharp rise in high blood pressure among children is deeply concerning and largely driven by increasing childhood obesity — an entirely preventable condition,” Prof. Steve Turner, president of the Royal College of Paediatrics and Child Health, toldThe Guardianabout the study. “These findings mirror what paediatricians are seeing on the frontline. Children are presenting not only with hypertension, but also other serious conditions linked to obesity such as type 2 diabetes — once unheard of in children — asthma and mental health problems.”

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The Lancetstudy found that approximately 19% of children with obesity had high blood pressure, compared to 2.4% of children who were in healthy weight ranges.

Children with high blood pressure are likely to continue having this condition well into adulthood, Mayo Clinic says, which puts them at increased risk of having heart failure or a heart attack, a stroke, or kidney disease. The medical institution says the causes of childhood obesity, along with obesity, are a diet high in cholesterol or sodium, a sedentary lifestyle, and family history of high blood pressure.