From the beginning of development to maturity, the egg needs to go through five periods: the initiating follicle, the pre-sinus follicle, the sinus follicle, the pre-ovulatory follicle and ovulation, so the time needed for these five periods is 85 days, that is, it takes 85 days for the egg to develop from the beginning to the time it is expelled from the body. This is the reason why you should start taking oral folic acid 3 months before you prepare for pregnancy, and you should quit smoking and drinking, that is, you should change your bad habits from the beginning of follicle development, and then you can get a normal follicle to have a normal pregnancy.