WEDNESDAY, May 16 (HealthDay News) -- Babies born early and underweight have a greater chance of developing insulin resistance, glucose intolerance and high blood pressure when they become young adults than normal-weight babies, a new study says.
These factors can put a person at higher risk for heart disease and other health problems.
"Most small premature infants live healthy lives as adults," said study lead author Dr. Eero Kajantie, a pediatrician and senior researcher at the National Public Health Institute in Helsinki, Finland. "However, our findings indicate that they might be at a higher-than-average risk of common late-life disorders such as type 2 (adult) diabetes or cardiovascular disease."
The goods news is that the risk of developing these problems can be reduced with a healthy lifestyle, one that incorporates physical activity and a healthy diet and maintaining a normal weight, Kajantie added.
Kajantie's study is published in the May 17 issue of the New England Journal of Medicine.
Researchers have already established a link between small size at birth and glucose-regulation problems later in life. There is also a known association between preterm birth with very low birth weight and insulin resistance in childhood.
And research has shown that full-term babies with low birth weight have a higher risk of health problems such as hypertension, cardiovascular disease and type 2 diabetes when they reach young adulthood.
The question is whether insulin resistance, and therefore an elevated risk for various diseases, persists into adulthood in babies born premature and underweight.
The issue is a highly relevant one, given that advances in neonatal intensive care have drastically changed the prognosis for very-low-birth-weight infants. According to an accompanying editorial in the journal, in 1960, a baby born weighing 1,000 grams (2.2 pounds) had a 95 percent risk of dying. Today, that same child has as 95 percent chance of surviving.
As the new study noted, the first generation of infants who benefited from these improvements is now entering adulthood.
For the study, the researchers performed standard oral glucose tolerance tests in 163 young adults aged 18 to 27 who had been underweight at birth. They also performed the same tests in 169 people who had been born at term and at normal size. All participants also had blood pressure and blood lipid levels measured.
Body composition was measured in 150 adults who had been very-low-birth-weight babies and in 136 "normal" people.
The adults born with very low birth weights had a 6.7 percent increase in two-hour glucose concentration, a 16.7 percent increase in fasting insulin concentration, a 40 percent increase in two-hour insulin concentration, an 18.9 percent increase in the insulin-resistance index and an increase of 4.8 mm Hg in systolic blood pressure.
"We would simply encourage former preterm infants to follow a healthy lifestyle," Kajantie said. "It is important that, in particular, doctors following up adults would be aware of their patient's birth history. Preterm birth/very low birth weight may serve as an additional risk factor when deciding, for example, whether a workup of glucose tolerance or diabetes is needed in an individual patient."
And researchers should continue following the issue, Kajantie said.
"Further research is certainly needed, for example, to establish specific guidelines for follow-up of children/adults with very low birth weight," Kajantie said. "Moreover, this study actually tells us about infants who were treated at a neonatal intensive care unit over 20 years ago (1978 to 1985). There have been considerable developments in neonatal intensive care after that period."
Stanford University's Lucile Packard Children's Hospital has more on very low birth weight babies.
SOURCES: Eero Kajantie, M.D., Ph.D., pediatrician, senior researcher, National Public Health Institute, Helsinki, Finland; May 17, 2007, New England Journal of Medicine