Difficulty childbirth: Because of the large head size in some strains of cats, such as: Siamese and Persian, and here it is necessary to differentiate between fetal obstruction caused by the large size of the head, and between the hardship of the pregnant mother, which results from the inability of the mother to remove fetuses of the same size Normal, due to the occurrence of uterine insufficiency resulting from weakness in the uterine muscles and its inability to further contract and contract to expel the fetuses in their normal size, due to the long period of labor in the mother, or because of the low levels of the hormone oxytocin, which stimulates the uterine muscles to contract to push the fetus out.