Multi-suckling systems aim to improve animal welfare, but in these systems, a large variation is seen in piglet growth rate. This study investigated relationships between birthweight and growth rate, and other piglet traits in this system, and studied if specific traits are indicative of the ability of catch-up growth in low birthweight piglets. We found that birthweight was positively related with survival, growth rate, the number of sucklings, milk intake and feed intake, and with skin lesion scores. Irrespective of birthweight, fast-growing piglets tended to eat more feed, were present less often at teats of alien sows, and had more skin lesions. Our study provides little insight into the piglet traits that affect catchup growth in a multi-suckling environment, but it confirms the effects of piglet birthweight on survival and body weight gain, which is related to increased milk and feed intake.