Between the 11th to 18th day of Menstrual Cycle the growing egg (follicle) ruptures (ovulation) and a matured ovum (Oocyte) comes out from the ovary; then entered into the fallopian tube. For pregnancy to occur, a sperm must unite with the egg in the fallopian tube within this time. After intercourse sperms are deposited in vagina, the active sperms ascend through cervical canal, uterine cavity and enters in the fallopian tube. The fertilized egg (embryo) moves into the uterus after few days. In the uterus the embryo is implanted to the uterine lining and begins a nine-month process of growth.