by Will Boggs, MD

Last Updated: 2008-12-01 14:34:26 -0400 (Reuters Health)

Preterm-born infants have persistently lowered blood pressure during sleep that may be related to their increased risk of sudden infant death syndrome (SIDS), according to a report in the December issue of Pediatrics.

"Preterm infants are at increased risk for SIDS and so it is particularly important that parents follow all the safe sleeping guidelines," Dr. Rosemary S. C. Horne told Reuters Health.

Dr. Horne and colleagues from Monash University, Melbourne, Victoria, Australia, had previously demonstrated in healthy term infants that there was a fall in blood pressure at 2 to 3 months of age, the age when the SIDS risk is highest.

They investigated whether 25 prematurely born infants would exhibit altered blood pressure and heart rate patterns during sleep when compared with 20 age-matched term-born infants.

At 2 to 4 weeks and 2 to 3 months corrected age, sleep state had no effect on heart rate in term or preterm infants, the authors report, although heart rate was significantly lower in quiet sleep compared with active sleep at 5 to 6 months corrected age.

In contrast, the researchers note, average and systolic blood pressure was significantly lower in preterm infants than in term infants during quiet sleep and active sleep at 2 to 3 months corrected age. Diastolic pressure was also significantly lower in the preterm infants at 2 to 3 months and 5 to 6 months corrected age.

Compared with term infants, preterm infants had significantly lower respiratory rates during active sleep (because of a greater frequency of apneas and period breathing) at 2 to 4 weeks and 2 to 3 months corrected age.

"We have recently completed studies in these same infants using head up tilts to assess cardiovascular control and found that this is also impaired in preterm infants," Dr. Horne added. "We will also analyze baroreflex sensitivity and heart rate variability in these infants."

Pediatrics 2008;122:e1242-e1248.