MONDAY, Feb. 25, 2013 (HealthDay News) -- Most babies who are slow to put on weight in their first 9 months of life achieve a normal weight range by the time they're 13 years old, but tend to be lighter and shorter than many of their peers, according to a new study.
U.K. researchers looked at data from about 11,500 children in a long-term study of infants born in England in 1991 and 1992, and found that 507 were slow to put on weight before the age of 8 weeks and 480 were slow to gain weight between 8 weeks and 9 months. Thirty children belonged in both groups.
Infants in the earlier group (before 8 weeks) had almost caught up to the weight of their peers by age 2, while those in the later group continued to gain weight slowly until they were 7 years old, and then had a "spurt" between 7 and 10 years. But at age 13, the children in the late group remained considerably lighter and shorter than those in the early group and other children.
Compared to other children at age 13, those in the late group were an average of 12 pounds lighter and 1.6 inches shorter, and those in the early group were 5.5 pounds lighter and 1.3 inches shorter, according to the study published Feb. 25 in the journal Pediatrics.
"The reason the early group caught up more quickly may be because those infants had obvious feeding difficulties and were more readily identified at the 8-week check, resulting in early treatment leading to a more rapid recovery," study lead author Alan Emond, a professor at the University of Bristol, said in a university news release.
"Those children who showed slow weight gain later in infancy took longer to recover, because of the longer period of slow growth and because their parents were smaller and lighter, too," he said.
"Overall, parents can be reassured that well babies showing slow weight gain in the first year do eventually recover to within the normal range, but at 13 years tend to be lighter and smaller than many of their peers," Emond concluded.
The Nemours Foundation has more about children's growth.