Sperm count for IVF. Technician using a light microscope to count the healthy sperm cells in a sample of a man's semen. This is being done to assess the man's fertility in preparation for IVF (in vitro fertilisation). Healthy semen usually contains between 20-30 million motile sperm cells in every millilitre. IVF is used when a couple cannot conceive naturally. Sperm from the father is introduced to the mother's egg cells (ova) in a laboratory. If fertilisation is successful, one or more developing embryos are then placed into the mother's uterus, and a normal pregnancy will follow.