<B>Ovulation Factor</B> Problems with ovulation are common causes of infertility, accounting for approximately 25% of all infertility cases. Ovulation involves the release of a mature egg from one of the ovaries. After ovulation, the ovary produces the hormone progesterone. Before the onset of menstruation, progesterone transforms the lining of the uterus into a receptive environment for the implantation and nurturing of the fertilized egg.