Transfer usually refers to IVF, while window period usually refers to the period when the embryo is transferred to the uterine lining, which can be clarified by menstrual cycle projection or ultrasound examination. 1. Menstruation projection: It is crucial to find the window period for transfer. Missing the window period may lead to obstruction of embryo implantation or even retardation of fetal development. Therefore, it is necessary to determine the time of ovulation according to the menstrual cycle to determine the window period for transfer. 2. Ultrasound: This is also a way to determine the window period for implantation. The thickness of the endometrium can be checked by ultrasound to determine whether it is suitable for embryo implantation. The window period for transfer can be determined by a professional physician, and it is recommended that women should maintain a good state of mind, regular work and rest habits, and at the same time have sufficient nutrition, avoid picky eating.