Cardiovascular Consequences of Preterm Birth in the First Year of Life

The definition of a premature infant includes any infant born less than 37 completed weeks of gestation (Beck et al., 2009). This can be further divided into extremely, early and late preterm birth with those infants being born before 26 weeks of gestation being regarded as extremely preterm, between 26 and 34 weeks of gestation regarded as early preterm and those born between 34 and 37 weeks regarded as late preterm (Thilo and Rosenberg, 2010). Due to their reduced gestation, preterm infants are often born with a low birth weight (LBW) defined as a birth weight of less than 2500g, preterm infants are frequently also categorised as very low birth weight (VLBW), defined as less than 1500g and extremely low birth weight (ELBW), defined as less than 1000g (WHO, 2007). The worldwide rate of preterm birth is estimated to be 9.6% of all births, a total of almost 13 million births annually (Beck et al., 2009). Rates of premature birth vary between countries, but are around 10.6% in the USA, 6.2% in Europe and 6.4% in Australia (Beck et al., 2009). Despite a slight decrease in the last 4 years, the number of preterm births has been steadily increasing with a rise of greater than 30% over the past 30 years (Thilo and Rosenberg, 2010). This is due to a combination of factors including changing obstetric practices with a shift towards earlier delivery via either induction of labour or caesarean section and an increase in the number of multiple births (Thilo and Rosenberg, 2010). With improvements in neonatal intensive care techniques, the percentage of infants surviving premature birth has increased dramatically over the last two decades however, premature birth still has a significant impact on infant health and is associated with numerous neonatal problems both in the short and long term (Saigal et al., 2008). This review will focus on the problems associated with the cardiovascular system and its control during the first year of life.