To use progesterone cream effectively, apply it to a fatty area of the body. But don't overdo it; too much progesterone can harm your chances of conceiving.

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It's no secret that hormones play a major role in both the female and male reproductive systems. But one in particular -- progesterone -- is known as the "hormone of pregnancy" because of its part in regulating menstruation and ovulation [sources: Bowen; MSN]. If a woman has abnormally low levels of progesterone, it may be difficult -- even impossible -- for her to become pregnant. Adequate levels, on the other hand, can help a fertilized egg survive.

Fortunately, there are ways to increase progesterone. But first you will want to have a doctor test your current levels to ensure there really is a shortage of the hormone. If low progesterone is determined to be a probable culprit of your infertility, your doctor may prescribe progesterone.

Synthetic progesterone, known as progestogen, is available in many formulations, including pills, gels and suppositories. But because progestogen is associated with numerous side effects, some women opt to take a bioidentical version of natural progesterone, which is normally offered in an over-the-counter (OTC) skin cream.

There is a debate as to how effective natural progesterone cream is at promoting fertility. Experts doubt that creams absorb into the skin well enough to get into the system [source: Jelovsek]. Some, on the other hand, worry that natural progesterone creams allow too much of the hormone into the body [source: Hermann, et. al]. In addition, OTC formulations aren't pharmaceutical grade or FDA regulated [source: DiLeo].

Despite some misgivings among the medical community, there are fertility clinics that recommend natural progesterone cream for certain patients. And, ideally, the cream -- although OTC -- should be used only with guidance of a physician.

On the next page, learn more about how natural progesterone can lead to conception.