Sperm are produced inside the man's testicles and released through the penis during ejaculation. Sperm are about a hundred times smaller than the female egg and have three parts €“ a head containing the genes, a middle section that provides energy and a tail for swimming. On average, sperm can live for five days inside a woman's body, but in the correct conditions, they may live longer. Therefore, if a couple has intercourse in the days immediately before ovulation, the sperm will have time to travel up the oviduct and be ready when the egg is released from the ovary. Home tests that identify when the woman is ovulating allow couples to plan intercourse to maximise their chances of conception.