Yiallourou S., Witcomb N., Sands S. et al (2012). "The development of autonomic cardiovascular control is altered by preterm birth". Early Human Development, 89(3):145-152 Details
Customer Study Highlights
The first 6 months of infancy are an important developmental phase for maturation of autonomic innervation of the heart in healthy full-term babies. This also holds true for pre-term babies. However, it has been shown that, compared to age-matched full-term babies, babies born prematurely show signs of impaired autonomic cardiovascular control, which researchers suggest may be an important risk factor in sudden infant death syndrome (SIDS).
Using heart rate variability (HRV) and blood pressure variability (BPV) analyses, researchers at Monash and Harvard Universities further investigated suppressed maturation of autonomic cardiovascular control in pre-term infants. Of the 56 infants tested, 25 were pre-term (born at 28-32 weeks of gestational age, GA) and 31 were born full-term (38-42 weeks GA). Daytime sleep data were acquired using a 16 channel PowerLab and a Finapres Finometer device was used to record blood pressure.
The results showed that, at 5-6 months of age, pre-term infants had reduced total HRV power (0.04-1.5 Hz), indicating lower overall autonomic regulatory influence on heart rate. This was observed in both HRV frequency bands: LF, 0.04-0.15 Hz (“mixed parasympathetic & sympathetic drive”) and HF, 0.15-0.4 Hz (“parasympathetic”). Pre-term infants also showed lower LF BPV power at 2-4 weeks indicating reduced sympathetic vasomotor activity, although this reached parity with full-terms by 5-6 months of term-corrected age. HF BPV on the other hand didn’t: pre-terms showed 2-fold higher HF BPV power at 5-6 months of age compared to full-terms.
Impaired maturation of autonomic cardiovascular regulation in pre-terms poses an increased risk of SIDS, likely due to dampened blood pressure responses leading to uncompensated hypotension and difficulty to arouse from sleep. However, the authors comment that the low parasympathetic activity in preterm infants may resolve at older ages, as another study has shown normalization by 2–3 years term-corrected age in preterm infants.