"It is known that pills which contain only progestin alter the cervical mucus. They also interfere with implantation by affecting the endometrium and suppressing ovulation in some patients by reducing the presence of follicle-stimulating hormone (FSH). This mechanism is confirmed by the United States Food and Drug Administration (FDA), which stated that "Progestin-only contraceptives are known to alter the cervical mucus, exert a progestinal effect on the endometrium, interfering with implantation, and, in some patients, suppress ovulation." The manufacturers of the minipills also acknowledge this mode of action. For example, Syntex Laboratory spokesman Russ Wilks announced that its progestin-only Pill "... did not interfere with ovulation ... It seems to affect the endometrium so that a fertilized egg cannot be implanted.""