CBSE Class 9 Answered
A fallopian tube blockage typically prevents successful passage of the egg to the sperm, or the fertilized egg to the uterus.
If one or both fallopian tubes are blocked, the egg cannot reach the uterus, and the sperm cannot reach the egg, preventing fertilization and pregnancy.
It's also possible for the tube not to be blocked totally, but only partially. This can increase the risk of a tubal pregnancy, or ectopic pregnancy.
If only one fallopian tube is blocked, but the other is clear, it may still be possible for the sperm and ovum to meet and achieve pregnancy. It depends on how well the ovary on the side of the clear tube is functioning, and also what caused the blocked tube in the first place. (Also, since ovulation takes place on different sides from month to month, when the ovary on the blocked side ovulates, pregnancy cannot be achieved. So it may take longer to get pregnant.)