The chances of getting pregnant in one fallopian tube are around 50%, which is lower than the chances of getting pregnant in both fallopian tubes. Normally, in women of childbearing age, the ovaries ovulate once a month. Most ovarian ovulation occurs on one side of the ovary one month, and on the other side of the ovary the next month, which is an alternating ovulation. When one side of the fallopian tube is removed, or there is a blockage of the fallopian tube, only one side of the fallopian tube is open, so only after this side of the ovary ovulation, by the umbrella end of the fallopian tube to pick up the egg, the woman during this period of coitus to be able to get pregnant. In rare cases, if the ovary ovulation, need to reach the other side of the umbrella of the fallopian tube to pick up the egg, the egg and sperm combined to develop into a fertilized egg is less likely, and it is also easy to lead to the occurrence of ectopic pregnancy.