Why fertilization only takes place in fallopian tube?

Other places too: Normal pregnancies start with conception in fallopian tube. Then the embryo develops over a few days to mature enough to stick to the endometrium in the uterine cavity. If mature enough then it will attach and grow. If fertilization occured in the uterine cavity, then the embryo would fall out of the uterus. Ivf allows for outside fertilization. Fertilization outside tube yields ectopic pregnancy.