Progesterone Research Network        

Your Information Source on Bio-Identical Natural Progesterone

Questions? Call (877) 880-0170                                                                                                                         

Articles on HRT & Synthetic Hormones

History of HRT (Hormone Replacement Therapy)

1942 – Premarin (a synthetic estrogen ) is patented and sold as a treatment for menopause. Premarin is derived from PREgnant MAre’s uRINe and is an equine (horse) derived hormone

1966 – In the book, Feminine Forever, estrogen was recommended as a “cure” for the “tragedy of menopause” The author stated that women on estrogen therapy “will be much more pleasant to live with and will not be dull and unattractive.” Women began to ask their doctors for estrogen supplementation and Premarin sales escalated.

1969 – In the book Everything You Always Wanted To Know About Sex By David Reuben, M.D, estrogen was again promoted as a menopausal cure all. In the book, Dr. Reuben said,  “Without estrogen a woman comes as close as she can to being a man” and  “To many women, menopause marks the end of their useful life”.Women raced to their doctors to get the prescription. Premarin was the prescribed estrogen.

1975 – NEW ENGLAND JOURNAL OF MEDICINE published two hormone studies showing: Women who took menopausal estrogen alone without progesterone had four or more times greater risk of endometrial cancer. In women with 7 or more years of use à 14 times greater risk Doctors now began to give Provera (a progestin) along with estrogen.

1976 – 1st study (a small one) showed breast cancer may be increased in estrogen users. Subsequent studies showed increased health risks

1979 – Estrogen sales plummet

1985 – In an effort to regain estrogen sales, a new campaign was begun to promote estrogen for prevention of bone loss

1986 – Heart disease: The Framingham Heart Study conducted on 240,000 women reported that postmenopausal estrogen users had 50% more heart disease and twice as much cerebrovascular disease Conclusion: There was no coronary benefit from estrogen use.

1987 – Postmenopausal Estrogen Progestin Interventions Trial (PEPI) studies were begun to study hormone effect

1989 – Swedish study published in New England Journal of Medicine showed estrogen replacement therapy (ERT) caused a slight increase in breast cancer. With combination Hormone Replacement Therapy, breast cancer risk more than doubled.

1990 – PEPI Trial Completed. Showed HRT reduced some risks (LDL) but increased other triglycerides PEPI study was the first major study in the U.S. that compared natural micronized progesterone as one of its therapies. Investigators found that the natural progesterone protected the endometrium and did NOT negatively affect triglycerides

1994 - National Institutes of Health (NIH) authorizers Women’s Health Initiative. 25,000 women are involved and study will follow them for 8 ½ years and look at the long term effects of synthetic hormone replacement therapy (Premarin and Prempro)

1995 – American Journal of Obstetrics & Gynecology published an article stating that not only long-term but short-term use of Premarin had a 40% risk of acquiring breast cancer

1995 – Nurse’s Health Study: Women taking synthetic estrogen alone had a 36% increase risk of breast cancer, those on synthetic estrogen plus progestin had a 50% increase; those on progestins alone had a 240% increase risk.

1998 – HERS Study (Heart and Estrogen-Progestin Replacement Study (HER) show HRT did not help women who already had a heart attack and may cause more heat attacks and strokes in that group. Natural progesterone was not studied or offered as a choice.

2000 – WHI (Women’s Health Initiative) – study participants taking HRT are told women are experiencing heart attack and strokes and offered the chance to drop out. The NIH allowed the study to continue, apparently in hopes that the trend would diminish over time.

2001 – Women's Health Initiative is on-going 6 million women were using HRT 45 million prescriptions for Premarin were written 21.4 million were written for Prempro Premarin sales reach 2.04 billion dollars

2002 – July 9, 2002, the WHI HRT study is abruptly stopped with an enormous amount of media coverage. The participants had increased risks of breast cancer, heart disease, stroke and blood clots. Doctors urged to prescribe HRT only for short term relief

2020 – 60 million women will be in or through menopause. They are looking for a safe alternative to HRT.


Dr. John Lee’s research led him to state that progesterone protected against coronary artery spasm, and breast cancer. Progestins (synthetic) do not. His conclusion was that progesterone supplementation after menopause is far more effective in preventing coronary heart disease death than Estrogen alone or estrogen plus progestin. He also recommended natural progesterone for other symptoms of peri-menopause and menopause.