As Very-Low-Birth-Weight Babies Grow
Jan. 16, 2002 -- Each year in the U.S., about 40,000 infants are born weighing less than 3.3 lbs. As a group, these very-low-birth-weight babies face increased risk of a myriad of physical and developmental problems. But doctors don't really know how things usually turn out for these kids.
Now researchers who followed a group of very-low-birth-weight babies from infancy to adulthood may have some answers. Not surprisingly, educational and health disadvantages persisted through childhood and adolescence. But those born at very low weights were no more likely to engage in risk-taking behaviors like using alcohol or drugs.
"This is a very encouraging finding, because our hypothesis was that these children might be more susceptible to peer pressure, risk taking and criminal behavior," lead author Maureen Hack, MB, of the University Hospitals of Cleveland, tells WebMD. "Risk taking in children is associated with lower intelligence, academic performance, and frustration."
Approximately 1% of babies in the U.S. weigh less than 3.3 lbs. at birth. That puts them into the category of having a "very low" birth weight. Those weighing less than 2.2 lbs. at birth, or 1 kilogram, are considered to be at an "extremely low" birth-weight.
Before the era of neonatal intensive care units, few very-low-birth-weight infants survived. Today, babies who weigh as little as a pound and developed in the uterus for as little as 26 weeks have been known to survive. (Doctors usually consider a full-term pregnancy to last 36 to 38 weeks.)
In this study, reported in the Jan. 17 issue of TheNew England Journal of Medicine, Hack and colleagues revisited a group of very-low-birth-weight subjects born between 1977 and 1979 as they reached their 20s. The 242 study participants had an average weight of 2.6 lbs. at birth, after pregnancies lasting an average of just under 30 weeks. They were compared to a group of 233 people from the same inner-city population in Cleveland who were born at a normal birth weight.
Fewer low-birth-weight young adults graduated from high school, compared to the normal-birth-weight group (74% vs. 83%). And very-low-birth-weight men were significantly less likely to be enrolled in colleges or universities than their normal-birth-weight counterparts (30% vs. 53%). This was not true of women, however.