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Sleep: A Window Into Autonomic Control in Children Born Preterm and Growth Restricted
Stephanie R Yiallourou1,2, Euan M Wallace1,3, Christie Whatley4
1The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.
Insights
Children born preterm with fetal growth restriction (FGR) show altered heart structure, while preterm birth alone affects autonomic control. These early changes may increase future cardiovascular disease risk through distinct pathways.
Area of Science:
- Pediatric cardiology
- Neonatology
- Autonomic nervous system research
Background:
- Preterm birth and fetal growth restriction (FGR) are linked to adult hypertension.
- The underlying mechanisms for this increased cardiovascular risk are not fully understood.
- Investigating early life factors is crucial for understanding long-term health outcomes.
Purpose of the Study:
- To assess autonomic control and cardiovascular structure/function in children born preterm with FGR.
- To compare these parameters with children born preterm (AGA) and term-born controls.
- To elucidate potential mechanisms linking early life adversity to later cardiovascular disease.
Main Methods:
- Polysomnography with continuous noninvasive blood pressure monitoring was used during sleep.
- Heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity were analyzed.
- Echocardiography and vascular compliance measurements were performed; urinary catecholamines were assessed.
Main Results:
- Preterm AGA children exhibited increased parasympathetic activation and respiratory-related blood pressure changes during sleep.
- Children born preterm with FGR had smaller cardiac dimensions (left ventricular length, aorta, outflow tract).
- Vascular compliance was positively correlated with gestational age in preterm FGR children.
Conclusions:
- FGR combined with preterm birth impacts cardiac structure, not autonomic control, in children.
- Preterm birth alone affects autonomic control without altering heart structure.
- These distinct early-life alterations may contribute differently to future cardiovascular disease risk.
Study Objectives:
Preterm birth and fetal growth restriction (FGR) are both associated with risk of hypertension in adulthood. Mechanisms leading to this pathology are unclear. In children aged 5-12 years, who were born preterm and FGR, we used sleep as a tool to assess autonomic control with assessment of cardiovascular structure and function.
Methods:
Eighteen children born preterm and FGR, 15 children born preterm with appropriate birth weights for gestational age (AGA), and 20 AGA term-born children were studied. Children underwent overnight polysomnography with the addition of continuous noninvasive blood pressure (Finometer™). Spectral measures of heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity were assessed and overnight urinary catecholamine levels measured. Echocardiographic studies (Vivid7, GE Healthcare) were performed and vascular compliance assessed (Miller Instruments™). Statistical comparisons were adjusted for age and body size.
Results:
Compared to term children, preterm AGA children had increased high frequency HRV (p < .05) and BPV (p < .05) during sleep, reflecting increased parasympathetic activation and blood pressure changes related to respiration. Preterm FGR children had smaller left ventricular lengths, ascending aorta, and left ventricular outflow tract diameter (p < .05 for all) and vascular compliance was positively correlated with gestational age (r2 = 0.93, p < .05).
Conclusions:
FGR combined with preterm birth did not alter autonomic control but altered heart structure in children. In contrast, preterm birth alone altered autonomic control but had no change in heart structure. These changes in children born preterm and FGR may contribute, in part, to increased risk of cardiovascular disease later in life but by different mechanisms.