The objective of the study was to determine the effect of parity on sow reproduction traits and the effect of litter size on piglet losses from the birth to weaning. Sows from two herds (N=301) was monitored during their four parities. The number of total born, born alive, stillborn, weaned piglets were monitored and percentage of piglet losses was calculated from obtained data. The lowest number of total born piglets was found in parity 1 (15.92 ± 3.38), the highest number of total born piglets was found in parity 4 (23.67 ± 3.13). There were also found statistically significant differences (P