The answer is mixed, according to an article in Disability Scoop, "Despite Advances, Many Preemies Still Face Severe Disabilities" by Michelle Diament, 12/11/12.
Neither one of my sons' disabilities were caused by prematurity. Although they both survived because of care given to them in intensive care neonatal nurseries, that care was not enough to spare them from lives with profound mental and physical disabilities.
After Danny was born in 1976, I used to see photographs and news stories about premature infants and others who had survived and thrived after overcoming extremely difficult circumstances at the time of birth. I noticed one day at the hospital where Danny was born - I think we were making one of our treks to see his orthopedic surgeon - a bulletin board full of photographs from a recent reunion of "graduates" from the neonatal intensive care unit. Hmm?, I thought. We weren't invited. (You see how petty I can be when it comes to a perceived insult to a child of mine.)
Among the children at the reunion, not one was in a wheelchair. One wore glasses but otherwise there were no visible signs that any of them had significant disabilities. In the crowd I hung out with, mostly parents whose children were similar to Danny, many of those children had done time in the same neonatal intensive care nursery. I have no idea if there was any deliberate plot to exclude children like mine from the reunion party - maybe their parents were too tired or just didn't feel like celebrating. But since then, I have always been somewhat skeptical about claims that we are making tremendous progress in preventing and treating severe disabilities.
The Disability Scoop article sites two British studies. One concludes that, "Survival of babies born between 22 and 25 weeks’ gestation has increased since 1995 but the pattern of major neonatal morbidity [the incidence or prevalence of disease in a population] and the proportion of survivors affected are unchanged. These observations reflect an important increase in the number of preterm survivors at risk of later health problems." Another, in comparing outcomes between 1995 and 2006, concludes that "At follow-up the findings are mixed: there is some evidence of improvement in the proportion of babies who survive without disability, an improvement in developmental scores, and a reduction in associated neuromorbidity (seizures and shunted hydrocephalus), but no change in the rate of severe impairment."
Overall, there are more preemies who survive without any disability, and good for them, but the proportion of those with severe disability has remained the same.