There are many couples out there who find it difficult to conceive a baby. In a normal pregnancy, a male sperm cell fertilizes an egg cell from a woman. After fertilization, the fertilized egg gets attached to the wall of the uterus and starts to develop into a baby. But in some cases sperm cells? fail to fertilize the egg and the embryo will not be formed and pregnancy will not be happening. Well, there are many reasons behind this problem.