Progesterone cream primer: pushed aside for years by its headline-grabbing cousin estrogen, progesterone is finally getting the attention it deserves.(SUPPLEMENTS: ESSENTIAL FOR WOMEN)

Hormones can be a woman's best friends--or her worst enemies. Throughout life, the key to hormone harmony lies in balance, particularly as we age. During perimenopause, estrogen and progesterone production typically begin to fall, paving the way for menopause. But trouble starts because progesterone frequently plummets while estrogen production simply slows. The result: estrogen dominance, a condition that can lead to weight gain, fatigue, mood swings and bloating, as well as increased risk of heart disease, osteoporosis and certain cancers.

For many women, the key to correcting estrogen dominance is simple--applications of low-dose progesterone cream. Erika Schwartz, MD, author of The 30-Day Natural Hormone Plan, frequently recommends progesterone cream to her patients, often with "remarkable" results.

Hormone Dilemma

Progesterone cream, a member of the "bioidentical" hormone family, is gaining popularity as women search for alternatives to the conventional medical management of menopause, hormone replacement therapy (HRT). A controversial practice for more than 30 years, HRT relies mostly on pharmaceutically developed synthetic hormones. In 2002, researchers called an early halt to the Women's Health Initiative, a study examining risks and benefits of HRT. The reason: an increased risk of stroke, heart disease and breast cancer among participants.

Media coverage about these dangers left many women in medical limbo. Whether they were concerned about long-term risks or simply hoping to ease the discomforts of hot flashes, low libido and insomnia, women found they had few choices in conventional medicine. The search led many women to bioidentical hormones, and progesterone cream in particular.

Making Sense of Molecules

Bioidentical hormones, made of soy and yam extracts, are perfect molecular matches with the hormones the body produces, while synthetic supplements are essentially foreign substances. The structure of something as small as a molecule might not seem all that important, but our bodies notice. The mismatched molecules of synthetic progesterone, known as progestin, have been linked to migraines, depression, breast cancer, birth defects and an increased risk of stroke.