The risk factors for high blood pressure are well established and understood for adults. While children share these risk factors, the contribution that each factor makes on the overall risk is less clear. A significant amount of research - both clinical and laboratory - has been aimed at trying to figure out how risk factors contribute to the overall risk profile in children. Special interest has been given to the topics outlined below.
Body Weight and Body Mass Index
Body weight and body mass index are strongly linked with the risk of hypertension in children. Increasing body weight is a reliable signal indicating increased risk of developing high blood pressure. One study of elementary and middle school children found that only 2% of children with a body mass index (BMI) below the 5th percentile developed high blood pressure, compared with about 12% of children with a BMI in the 95th percentile. In other words, increasing body weight leads to increasing blood pressure.Socio-Economic Factors
There is evidence that adults from low socio-economic backgrounds have an increased risk of health problems, including high blood pressure. Many studies also have found this trend in the pediatric population. One study found that, across all ages (<18) and body weights, children from lower socio-economic households had a dramatically increased risk of developing high blood pressure. While the risk was higher for minority ethnic groups, the trend still applied when the data was adjusted for racial background. The reasons for this increased risk are an intense focus of ongoing study, and a number of theories, including decreased access health care resources, have been examined as possible causes.Ethnicity
In adults, there is a strong link between ethnic background and the risk of high blood pressure. While these trends are well established in adults, they have not been definitively established in children. One famous study - known as the Bogalusa Heart Study - seemed to show different blood pressure risk trends between black and white children, but several later studies have been unable to replicate the results, showing no risk difference between the two groups. Initial data examining children from Asian populations seemed to show that they were at increased risk (exactly the opposite of the adult trend). While this data has been replicated by other studies, it is inconsistent, and not considered conclusive.Family History
As in adults, family history appears to play a strong role in a child's risk of developing high blood pressure. In clinical studies, children with hypertension were about 350% more likely to have parents with hypertension compared to children with normal blood pressure. Some researchers have estimated that about 70% of the cases of high blood pressure in a family are a direct result of genetics. Reinforcing the role of genetics in family history is the observation that no link has ever been observed between the blood pressures of parents and their adopted children.Breastfeeding
Two studies involving more than 15,000 children have found that children who are breastfed appear to have a lower risk of developing high blood pressure early in life. On average, these children had systolic blood pressures that were about 1.2 mmHg lower than bottle fed children. Diastolic pressure was also lower, but systolic pressure continued to show a decreasing trend for as long as breast feeding continued. No long-term studies have been done to track these reductions out into adolescence or adulthood, but data from older children suggests the effect may be temporary.
