Natural Progesterone = Less HRT Bleeding
May Add to HRT Benefits, Lessen HRT Dangers
Nov. 1, 2002 -- Hormone replacement therapy (HRT) with a natural hormone leads to less bleeding than HRT with a synthetic version, a clinical trial shows. And study data suggest that the natural product may also have more benefits and fewer risks.
Estrogen replacement by itself increases the risk of uterine cancer. That's why most women on HRT add another hormone -- progesterone -- which eliminates this risk. The most widely used form of progesterone is MPA, a synthetic version of the hormone. But there's also MP (micronized progesterone), which is chemically identical to the natural hormone.
From 1987 to 1993, the PEPI study compared HRT with horse-derived estrogen (Premarin) in combination with MP or different regimens of MPA. A new analysis of the study data appears in the November issue of the Journal of Obstetrics and Gynecology.
"During the first six months, when many women stop taking HRT because of bleeding problems, we found that estrogen plus MP caused significantly less bleeding than the other combinations using MPA," senior study author Robert D. Langer, MD, MPH, University of California, San Diego, says in a news release.
A more recent study, the Women's Health Initiative, found that a Premarin/MPA combination slightly increased breast cancer risk but took away some of the heart-protective effect of estrogen alone. The PEPI data suggests that MP does not block this benefit of estrogen.
"We also believe that the form of HRT with the least bleeding -- estrogen plus MP -- may be the form less likely to cause the increased health risks associated with estrogen plus MPA," Langer says.
The current study was supported by a grant from Solvay Pharmaceuticals, maker of a brand of MP capsules called Prometrium.