Babies born very early or with very low birth weights — only a couple pounds — are known to have a higher likelihood of disability. But they may be just fine over the long term.
A recent study found that adults who had very low birth weights had a similar quality of life as adults born with a normal birth weight.
Those with very low birth weights did tend to have lower rates of education and higher rates of some social or mental disabilities compared to those with normal birth weights.
However, the adults with low birth weights were no more likely to have mental health concerns and were less likely to be involved in criminal behavior compared to adults with normal birth weights.
Overall, those with disabilities tended to be adults who had already been diagnosed with a disability in early childhood.
This study, led by Brian A. Darlow, MD, of the Department of Pediatrics at the University of Otago Christchurch in New Zealand, aimed to learn whether children born with a very low birth weight were at any higher risk for long-term social or health difficulties.
The researchers interviewed 230 adults, aged 22 to 23, who had been born with a very low birth weight (less than 3.3 pounds). As a group, their average birth weight had been an average of 2.5 pounds.
These adults' health, levels of education, financial situations and social networks were compared to those of 69 adults of the same age who had been born with average birth weights (an overall average of 8 pounds).
Both groups had similar ratios of men and women, different ethnicities and different geographic home regions.
Those with very low birth weights were part of a larger group of 413 babies followed from birth. About a third of that group had been born before 28 weeks of pregnancy, about a third weighed less than 2.2 pounds, and a little over half had been given steroids before birth.
When these children were 7 and 8 years old, the 298 still surviving children were assessed for neurodevelopment disabilities.
About 5 percent had severe disability, 5 percent had moderate disability and 15 percent had mild disability (mainly an IQ significantly below the average).
At that time, the children with low birth weights also had poorer school achievement and higher rates of behavioral problems than children born with average birth weights.
In the current study, those same children, now adults, were 12 pounds lighter and 1.7 inches shorter, on average, than the adults who had been born with normal birth weights.
In addition, 13 percent fewer adults from the very low birth weight group had gone to college and 16 percent fewer had finished a university degree compared to those with average birth weights.
Also, 24 percent more of the very low birth weight adults had relied on welfare and 21 percent more had few or no friends compared to the adults with normal birth weights.
Twenty percent more adults born with low birth weights had wheezed in the previous year compared to adults with average birth weights.
Yet most of the adults with low birth weights who had poorer social, educational or physical outcomes were those who had previously already been identified as having disabilities when they were young children.
In fact, the adults with very low birth weights rated their overall quality of life and ability to function with very similar ratings to those of adults with average birth weights.
Rates of substance abuse and mental health were not substantially different between the two groups, and a higher percentage of the adults with normal birth weights had been involved in criminal behavior compared to those with very low birth weights.
"Despite some evidence of health, educational, and social difficulties, former very low birth weight young adults obtained similar scores across many aspects of health and social functioning as their same age peers, with some differences largely confined to those with previous disability," the researchers wrote.
Andre Hall, MD, an OBGYN at Birth and Women's Care, PA in Fayetteville, NC, said that birth weights are often the greatest predictor of future health of children.
"This is one of the main reasons medical providers work so diligently to get a woman to full term," he said. "Historically, babies born early and at very low birth weight had no chance of survival."
But progress in healthcare has changed that, he said.
"Now with the advent of advanced medical care, we are able to save more and more of these smaller babies," Dr. Hall said. "Smaller babies used to almost universally have disabilities that would be lifelong. Much of this, too, has now changed in that if these small babies are able to get beyond the early critical period without significant disabilities, they often will lead normal, healthy adult lives."
But it is still hard to know how well each individual child will fare, he said.
"We are still unable to predict which low birth weight baby will ultimately be normal and which will be hampered by lifelong pain and suffering," Dr. Hall said. "As a result, physicians and patients must continue to work together to reach the goal of full term for each and every baby."
This study was published November 18 in the journal Pediatrics. The research was funded by the New Zealand Child Health Research Foundation (Cure Kids). The authors reported no potential conflicts of interest.