Using Progesterone to Prevent Miscarriages

A Closer Look at This Controversial Topic

Chances are you may have heard of progesterone, particularly if you have had recurrent miscarriages. Progesterone is a hormone associated with pregnancy and the menstrual cycle.

Levels of progesterone rise every month after ovulation, preparing the lining of the uterus for pregnancy. In a non-pregnant menstrual cycle, progesterone levels rise after ovulation and fall just before a woman gets her menstrual period. When pregnancy occurs, the progesterone level should remain elevated. The ovaries produce the majority of progesterone through most of the first trimester. Eventually, by about the tenth week of pregnancy, the placenta takes over production of the hormone.

Because progesterone plays a role in maintaining the uterine lining, some researchers have theorized that having low progesterone before a miscarriage might actually play a role in causing the miscarriage. But whether supplementing progesterone actually prevents miscarriage is a matter of debate.

Current Research

A 2012 statement from the American Society for Reproductive Medicine suggested that for women with sporadic miscarriages, progesterone is not useful. However, for women who have had recurrent (three or more) miscarriages, progesterone supplementation may be helpful. Women using reproductive technologies such as IVF may also be prescribed progesterone supplements.

In 2013, a review of 13 scientific studies also concluded that "for women with unexplained recurrent miscarriages, supplementation with progestogen therapy probably reduces the rate of miscarriage in subsequent pregnancies."

However, a randomized study of over 800 pregnant women, published in 2015, found that treatment with progesterone "did not result in a significantly higher rate of live births among women with a history of unexplained recurrent miscarriages." And another randomized study, this one of over 4,000 women who experienced bleeding in early pregnancy (not necessarily recurrent miscarriage), similarly showed no fewer miscarriages among women who took progesterone. This research was published in 2019.

What Is the Controversy?

Low progesterone in pregnancy is definitely associated with miscarriage. Understanding why is the issue. On one hand, too-low levels could theoretically cause miscarriage if the uterus is not ready to support a pregnancy, perhaps because the ovaries have problems producing enough progesterone for some reason.

On the other hand, many doctors believe that low progesterone merely means that a miscarriage is impending for other reasons. With this line of thinking, the low levels are the first sign that the body is preparing to miscarry a pregnancy that has already failed (for example, due to chromosomal abnormalities in the developing baby), and progesterone supplementation is useless.

Right now, no one knows the correct answer, and the subject tends to be a matter of hearty debate.

Pros of Progesterone Therapy

Individual physicians may have clinical experience seeing women have recurrent miscarriages and then have successful pregnancies after progesterone supplementation, and so they might be strong believers in the idea that it actually does work.

Some physicians use progesterone supplements only in women who have already tested as having low progesterone. Physicians who use this approach may feel that the existing studies have not adequately screened patients, as many studies on progesterone currently have not differentiated women with low progesterone levels from women who have had miscarriages for other reasons. Again, they may have clinical experience seeing women with low progesterone levels end up carrying a baby to term after supplementation, so they believe that it works.

Given that the body naturally produces progesterone during pregnancy, and many supplements have a chemical makeup identical to the progesterone produced in the body, many physicians feel that supplementing women who have low levels is unlikely to do any harm.

Cons of Progesterone Therapy

Physicians who do not prescribe progesterone supplements may feel hesitant to prescribe any drug without a clear indication that it works—and they have a good historical ground to stand on. In the 1950s through the 1970s, physicians prescribed a drug called DES to pregnant women with the idea that it would prevent miscarriage—the drug later turned out to cause numerous reproductive abnormalities in children.

Although most physicians feel progesterone supplements are probably safe, it's impossible to say whether in 10 or 20 years a study might uncover risks to using artificial progesterone supplementation during pregnancy. Physicians may wait for clear guidelines before proceeding.

Physicians may also feel that, until scientific evidence demonstrates a clear benefit, it is more likely that the low progesterone merely means an impending miscarriage, and that prescribing progesterone when a pregnancy is already destined to miscarry can delay the onset of the bleeding.

In discussing anecdotal evidence in which progesterone seems to work, doctors who reject progesterone supplements may point to the idea that women with recurrent miscarriages tend to have a high success rate even without treatment—so in an uncontrolled setting, it is just as likely that a woman supplemented with progesterone would have had a successful pregnancy even without treatment.

Current Practice

Physicians have different opinions on progesterone, so you will find some who prescribe it to every woman who has had recurrent miscarriages, others who prescribe it only to women who have low levels of progesterone, and still others who never use progesterone supplements (except for patients using artificial reproduction methods).

It is true that no one really knows whether or not progesterone supplements work, and that no amount of progesterone is going to make a difference in the ultimate outcome of women who have miscarriages due to chromosomal abnormalities or similar causes.

A Word From Verywell

Progesterone supplements are probably safe. No one has found evidence that they can cause harm. If your physician is advising you to use progesterone, be sure to discuss any concerns you may have and take both sides into account before making your decision. Similarly, if your physician is not offering to prescribe progesterone, be sure to consider the reasons behind that stance before making a decision about your future care.

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