Babies who are slow to gain weight in the first months of their lives generally catch up with their peers by age 13, a new study has found.

Researchers said the results would reassure parents whose babies fail to put on weight quickly. Study by the University of Bristol shows that most babies who are slow to put on weight in the first nine months of life have caught up to within the normal range by the age of 13.

There are significant differences in the pattern of 'catchup', depending on the infant's age when the slow weight gain occurs.

New findings, published in the journal Pediatrics, are based on data from 11,499 participants of the 90s, and provide the most conclusive and reassuring evidence for parents that, with the right care, many infants who fail to put on weight quickly in the first 9 months will catch up over time.