vors who are “normal” divided by all live births. Generally, “normal” means no major cerebral palsy, mental retardation, or severe sensory impairment (i.e., no neurosensory impairment). As a concept, intact survival is most useful at the limit of viability, when the mortality rate is so high. Two recent regional studies have reported survival without major disability: 0 to 0.7 percent for those with gestational ages of less than 23 weeks, 6 percent to 35 percent for those with gestational ages of 23 weeks, 13 to 42 percent for those with gestational ages of 24 weeks, and 31 to 56 percent for those with gestational ages of 25 weeks (Doyle, 2001; Wood et al., 2000). This concept of survival without disability may be useful for discussions with prospective parents as they face the impending delivery of their infant at less than 26 weeks gestation (see Appendix C).
The rates of mortality (discussed in Chapter 10) and neurodevelopmental disability for moderately preterm infants; that is, those born between 32 and 36 weeks gestation or those weighing 1,500 to 2,499 grams at birth, are higher than those for infants born fullterm (although they are lower than those for infants born more prematurely). Although children born between 32 and 36 weeks of gestation constitute only about 8 to 9 percent of all births, they account for 16 to 20 percent of children with CP (Hagberg et al., 1996; MacGillivray and Campbell, 1995). Children born late preterm (or near term) have also been reported to have more developmental delays of infant milestones (those born at 33 to 36 weeks gestation) and more difficulty with hyperactivity, fine motor skills, mathematics, speaking, reading, and writing (those born at 32 to 35 weeks gestation) (Hediger et al., 2002; Huddy et al., 2001).
Authors of studies of the outcomes for children born preterm have struggled with how to convey the full range of outcomes. Although the majority have focused on cognitive outcomes and clinical diagnoses of neurodevelopmental disabilities, some have taken a more practical approach and have described what survivors of preterm birth have been able to do.
The acquisition of motor and adaptive milestones is a means of conveying the functional abilities of a toddler. Wood and colleagues (2000) found that at 30 months from term 90 percent of preterm infants born at less than 26 weeks gestation could walk, 97 percent could sit, 96 percent could feed themselves with their hands, and 6 percent could speak. In a similar study of children weighing less than 1,000 grams at birth, at 18 months from term 93 percent could sit, 83 percent could walk, and 86 percent could feed