Birth weight, gestational age, and blood pressure: Early life management strategy and population health perspective

Abstract

The incidence of hypertension (HTN) is rising worldwide with an estimated prevalence of 22%, 7.5 million deaths (12.8%). It is a major risk factor for coronary heart diseases and hemorrhagic strokes. In Oman, the crude prevalence of HTN was 33.1%, whereas the age-adjusted prevalence was 38.3%. Among Gulf Cooperation Countries, 47.2% of the individuals were hypertensive, and women were more likely to have HTN than men. Similarly, the prevalence of low-birth-weight (LBW) is also rising globally with the more prevalent incidence in developing countries reaching almost a rate just lower than 20.0/100 births. In Oman, the prevalence of LBW was 4.2% in 1980, which doubled (8.1%) in 2000 and has shown a slow but steady increase reaching 10.2% in 2013. LBW term is the most commonly used surrogate measure of intrauterine growth retardation and has been related to increased cardiovascular mortality, due to increased risk of cardiovascular risk factors, including blood pressure (BP), diabetes, cholesterol level, and other risk factors. The epidemiologic evidence clearly points to an inverse association between birth weight and many hemodynamic cardiovascular risk markers. Possible mechanisms operating in fetal life that might determine BP include the structural development of resistance arteries, the setting of hormone levels, and nephron endowment. Retarded fetal growth leads to permanently reduced cell numbers in the kidney. Patients with high BP had almost 50% less number of glomeruli compared to that of the normotensive individuals, and subsequent accelerated growth may lead to excessive metabolic demand on this limited cell mass. It is not merely a reduced nephron number that is responsible for HTN, but compensatory maladaptive changes that occur internally when nephrogenesis is compromised. The likelihood of an adverse outcome is greatly amplified in those born with LBW who later develop obesity or an increased ponderal index.