Housing of lactating sows raises ongoing animal welfare concerns. The study aimed to examine whether farrowing pen design affects sow behaviour and piglet safety. We predict that sows will use lying-down supports more before crate opening and that increased space after crate opening will not increase piglet trapping. Nineteen sows were observed in temporary farrowing crates, with behaviours recorded at three time points and analysed using mixed models. Sows reduced their use of supports after crate opening, lying-down events lasted longer when supports were used, and piglet trapping was rare. Providing sows with more space allows natural behaviour without compromising piglet safety.