And how long after sex does implantation in the uterus occur?

Pregnancy . Fertilization of an egg by sperm occurs in the fallopian tube, usually within 24hrs after ovulation. The fertilized egg than travels down the rest of the tube towards the uterus where implantation occurs. This is usually 5-7 days after fertilization (sex). A sensitive pregnancy test will become positive at this time, before a woman may even know she is pregnant!