The current study investigated the association of maternal and paternal risk clusters with the incidence of HTN in school-aged children over a 13-year follow-up. Our results indicate cardio-metabolic risk factors as the most important variable distinguishing parental risk clusters in both parents. Furthermore, another finding was the significant prognostic values of maternal risk clusters to predict HTN in their children, which was not supported by our data regarding the paternal risk cluster. In addition, boys compared to girls and children with higher BMI were more likely to be hypertensive in future.
In the current study regarding socio-demographic characteristics of parents, only employment status in fathers and age in both parents played important roles, a result consistent with previous data, suggesting the influential effect of family socioeconomic status (SES) defined as parental employment and family income on children’s general health and risk of CVD development in adulthood [34-36]. Accordingly, previous findings in Iran showed that moderate and low familial economic status could increase the incidence of HTN in school-aged children . The Young Finns Study tracking BP in children for 30 years until adulthood also indicated the contribution of parental occupation status in elevation of offspring’s BP . A potential explanation might be that parental unemployment and low income could result in both mental and physical risk factors such as anxiety, depression and obesity which could result in increased BP in their children [35, 38].
According to current findings, in both parents, the most important factors in distinguishing high and low parental risk clusters were essentially cardio-metabolic risk factors including MetS, HTN and weight status while physical activity was the least significant one. Most previous studies attempting to unveil the impact of parental cardio-metabolic risk factors in association with childhood HTN, have considered these factors separately and underscored the importance of family history of HTN and parental weight status in increasing risk of HTN in their children [7, 12, 39-41]. Even in Iran, HTN and obesity of parents were found to be potential risk factors resulting in elevated BP in children . Most existing studies have not considered the synergic effects of parental cardio-metabolic cluster on the BP level of their young offspring. However, in line with our findings, a cohort study in Japan revealed that clustering of maternal history of cardio-metabolic disorders including HTN, diabetes and dyslipidemia makes individuals more susceptible to clustering of these disorders in the future . Meanwhile, another study in Germany referred to the interrelation of parental HTN, obesity and smoking status as a combination of risk factors which could predispose children to HTN .
In the current study, only the maternal risk cluster appeared to have prognostic value in predicting HTN incidence in children not the paternal one. The association between maternal HTN and weight status and children’s BP level has been documented previously . However, limited data exist supporting the role of maternal cardio-metabolic characteristics as a risk cluster to predict offspring’s HTN; among those existing studies, a cohort study in Japan revealed that CVD outcomes including HTN in adult offspring were strongly influenced by the synergic effect of maternal cardio-metabolic history but not paternal history of these disorders . In Iran, the Isfahan Cohort Study also emphasizes the significance of screening maternal cerebrovascular diseases including HTN, diabetes, hyperlipidemia and obesity in the development of these risk factors in female children . A combination of interrelated mechanisms including environmental, genetic and epigenetic factors may elucidate the prognostic value of maternal cardio-metabolic risk clusters in association with offspring’s HTN incidence . Previous data suggest that healthy children of hypertensive mothers, compared to those without family history of HTN tend to have higher insulin levels which could explain the common pathway for developing CVD in those children . Meanwhile, mitochondrial DNA-mediated inheritance could be a genetic explanation of maternal role in transmitting cardio-metabolic phenotypes including HTN to their children . Greater shared environment with mothers resulting in similar lifestyles and behaviors, including dietary habits may also contribute to these components as well .
In line with previous data, male children and those with high BMI in this study appeared to be at greater risk of developing HTN in future. The predisposing role of gender in children to sustain high BP has been proposed in previous studies, implicating the higher incidence of HTN in male children [8, 10]. A systematic review on the prevalence of HTN in 122053 adolescents, consistent with the current findings, also demonstrated that besides the methodological difference in studies, male adolescents have higher odds of high BP, especially in low- and middle-income countries . Although most previous studies in Iran indicate higher BP incidence in boys [17, 47, 48], a few found only slightly significant difference or even contradictory results [18, 49]. The correlation between obesity and HTN in children is well established in literature which is in line with current findings [8, 50]. Studies from different parts of Iran have also documented the influential impact of high BMI on increasing BP in this age group [17, 18, 21, 48].
Among strengths of the current study, the large sample size, its longitudinal nature accompanied by long-term follow-up, and data collection for both parents are of significance. Some limitations of this study should also be mentioned. In this study, parental nutrition- and family income information were unavailable and were not included in the study analysis. Also, conducting the current study on an urban population could reduce the generalizability of the current findings, for which further research in suburban and rural areas are recommended.
In conclusion, the current results underscore the prognostic value of maternal risk cluster in predicting the incidence of HTN in their offspring. Highlighting this finding will be valuable for health policy makers to identify the most vulnerable children for HTN and designing preventive strategies.