The number of the healthy weaning piglets provided per sow per year is a determinant for profits available in swine production. Maternal diets supplementing with fish oil could change the fatty acid profile of the reproductive tissues, embryo and fetal tissues, and was observed to play a critical role in improving litter size of farrowing, enhancing the growth performance of suckling piglets and promoting the health status of sows and neonatal piglets. In conclusion, it is necessary to fortify 1%～2% fish oil in the maternal diet during gestation and lactation to enhance the reproductive performance of the sow.［Chinese Journal of Animal Nutrition, 2010，22（2）:251-258］