Low birth weight matters later, too

Premature babies weighing less than 1.5 kilograms–about 3 pounds, 5 ounces–at birth grow up to have lower achievement scores on standard tests and are less likely to go to college than are full-term babies weighing more than twice as much, a study finds. On the other hand, these premature infants tend to be less mischief-prone as they grow, researchers report in the Jan. 17 New England Journal of Medicine.

Scientists tracked 242 babies who on average were born 7 weeks premature and weighed 1.18 kg at birth. The researchers compared the group’s progress at age 20 with that of 233 people who were born full-term and who averaged 3.28 kg at birth. All the babies were born in the late 1970s in inner-city Cleveland.

Although socioeconomic status was similar for all the babies, fewer in the low-birth-weight group were enrolled in four-year colleges. They also scored lower on IQ tests.

Even so, the young adults born prematurely were significantly less likely to use illicit drugs or to have broken laws other than traffic violations by the time they were interviewed. This result could stem from closer parenting of these children, speculates study coauthor Maureen Hack, a neonatologist at Case Western Reserve University in Cleveland.

The educational and risk-taking differences emerged even after researchers took medical problems into account, Hack says. The premature babies developed more neurological problems, cerebral palsy, and other chronic illnesses than the others did.