In view of the forthcoming UK ban on stall and tether housing for sows, the long-term consequences of housing pregnant pigs in alternative systems were assessed. The objective of the study was to examine the effects of two indoor group-housing systems on measures of the welfare of pregnant pigs, and to compare pigs housed in these systems with pigs housed in stalls. The study followed 63 female pigs from early life until their fourth pregnancy. A longitudinal experimental design was used to obtain information on how the pigs responded to their initial introduction to the three housing systems (during the first pregnancy), and how they adjusted to the systems over time (in the fourth pregnancy).