Scientists from Monash University, Melbourne have shown that infants born prematurely have lower blood pressure during sleep in the first six months of life, compared to healthy, full-term infants. 

Scientists at the Ritchie Centre for Baby Health Research, Monash Institute of Medical Research, believe this may be one reason premature infants are at an increased risk of Sudden Infant Death Syndrome (SIDS), which causes about 2,500 deaths per year in the United States and thousands more throughout the world..

Chief Investigator, Associate Professor Rosemary Horne, said that previous studies have shown that prematurely-born babies are at a significantly increased risk of SIDS; approximately 20 percent of all SIDS cases occur in preterm babies, though preterm babies comprise only 8-10 percent of infants born.

"It has been hypothesised that the underlying mechanism of SIDS involves a fall in blood pressure during sleep combined with a failure of the baby to arouse from sleep which would normally restore blood pressure," Associate Professor Horne said. 

"Our study has now provided evidence as to why preterm babies are at a higher risk for SIDS."

The study monitored the blood pressure of 25 preterm and 20 full-term infants at two to four weeks; two to three months and five to six months. Blood pressure was lower during sleep in the preterm infant group at all ages studied, but was lowest in the two to three month age group, when the risk of SIDS is highest. 

"Our recommendation is that additional research needs to be undertaken to determine whether preterm infants also have impaired cardiovascular control, as this may also contribute to the higher rate of SIDS in preterm infants, particularly when sleeping face down/on the stomach," said Associate Professor Horne. 

"Parents of both term and preterm infants should follow the advice of SIDS and Kids for infant safe sleeping practices and always sleep their infant on his/her back, keep their baby away from cigarette smoke and ensure that the baby's head cannot be covered by bedding," she said.