... corpus luteum and the placenta primarily produces them and some secondary sources in smaller amounts can be found in the liver, adrenal glands and breasts. Although oestrogen is present in both male and females, it is found to be significantly higher in women and is involved in controlling the menstrual cycle. As does progesterone, oestrogen also affects all aspects of the pregnancy and is particularly important in maintaining the health of the genital track, the reproductive organs and the breasts. Throughout pregnancy gradually the levels of progesterone in the blood fall and the levels of oestrogen rise. It is this process that brings about parturition as the oestrogen helps the uterine to contract & progesterone inhibits it. It is thought that miscarriage or premature births can be a result of insufficient levels of progesterone. As in most biological control systems the release and control mechanism for managing these hormones is known ...

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