A pproximately 14.9 million babies (11% of all infants born) worldwide are born preterm (<37 weeks) every year.1 Adults born preterm with very low birth weight (VLBW; <1500 g) or very (<32 weeks) or early (<34 weeks) preterm have higher blood pressure (BP) 2-6 and higher rates of hypertension compared with their peers born at term. There is some evidence of a continuous relationship between shorter length of gestation and higher BP. 7,8 Although most studies have relied on office-measured BP, we are aware of 5 studies that used 24-hour ambulatory BP (ABP) in adults born preterm. Those studies show either elevated BP 9-13 or hypertension, 9 and all are limited to adults born preterm at VLBW or very or extremely (<28 weeks) preterm, comprising the extreme 1% to 1.5% of newborns. Although 24-hour ABP predicts cardiovascular events better than office-measured BP, 14,15 it has not been studied across the entire range of preterm births.In addition to mean BP levels, previous studies have highlighted BP variability as a key factor underlying the progression of organ damage 16 and triggering vascular events. 15 It is also correlated with the development of hypertensive left ventricular hypertrophy. 17 BP variability is studied less often in adults born preterm. We hypothesized that preterm birth, across its entire range, is associated with elevated levels and larger variability of ABP in young adults. MethodsThis study is part of the ESTER (Preterm Birth and Early Life Programming of Adult Health and Disease) study, 18 a case-cohort study with subjects recruited through Northern Finland Birth Cohort Abstract-Adults born preterm have higher blood pressure (BP) than those born at term. Most studies have focused on preterm birth, and few have assessed BP variability, an independent risk factor of cardiovascular disease. We studied the association of preterm birth with 24-hour ambulatory BP, measured by an oscillometric device, in 42 young adults born early preterm (<34 weeks), 72 born late preterm (34-36 weeks), and 103 controls (≥37 weeks). Sleep was confirmed with accelerometry in 72.4% of subjects. The 24-hour systolic BP of adults born early preterm was 5.5 mm Hg higher (95% confidence interval, 1.9-9.3), awake systolic BP was 6.4 mm Hg higher (95% confidence interval, 2.8-10.1), and sleeping systolic BP was 2.9 mm Hg higher (95% confidence interval 0.3-7.5) when adjusted for age, sex, and use of accelerometry. The differences remained similar when adjusted for height, body mass index, physical activity, smoking, parental education, maternal body mass index, smoking during pregnancy, and gestational diabetes mellitus and attenuated slightly when adjusted for maternal hypertensive pregnancy disorders. Adults born early preterm also had higher BP variability as indicated by higher individual standard deviations of systolic BP and diastolic BP. Although our results were consistent with a dose-response relationship between shorter gestation and higher BP, the difference between the late preterm and term groups was not ...

Objective To evaluate cardiac autonomic function in adults born preterm. Study design We studied the association between prematurity and cardiac autonomic function using heart rate variability measurements in 600 adults (mean age of 23.3 years) from a geographically based cohort in Northern Finland. There were 117 young adults born early preterm (<34 weeks), 207 born late preterm (34-36 weeks), and 276 born at term ($37 weeks, controls). Autonomic function was analyzed by calculating time and frequency domain heart rate variability measurements using linear regression.Results Compared with controls, the mean difference in root mean square of successive differences (indicating cardiac vagal activity) was À12.0% (95% CI À22.2%, À0.5%, adjusted for sex, age, source cohort, and season P = .04) for the early preterm group and À7.8% (À16.8%, 2.0%, P = .12) for the late preterm group. Mean differences with controls in low frequency power (indicating cardiac vagal activity, including some sympathetic-and baroreflexmediated effects) were À13.6% (À26.7%, 1.8%, P = .08) for the early preterm group and À16.4% (À27.0%, À4.3%, P = .01) for the late preterm group. Mean differences in high frequency power (quantifying cardiac vagal modulation in respiratory frequency) were À19.2% (À36.6%, 2.9%, P = .09) for the early preterm group and À13.8% (À29.4%, 5.3%, P = .15) for the late preterm group. Differences were attenuated when controlled for body mass index and physical activity.Conclusions Our results suggest altered autonomic regulatory control in adults born preterm, including those born late preterm. Altered autonomic regulatory control may contribute to increased cardiovascular risk in adults born preterm. (J Pediatr 2019;-:1-8).