A recent study in the UK found that taking progesterone supplements during pregnancy is associated with a decreased risk of miscarriage, at least in some cases. To Teresa Kenney, a women’s health nurse practitioner in Omaha, the study came as no surprise.
That’s because the Pope Paul VI Institute for the Study of Human Reproduction, where Kenney works, has been using progesterone to support and maintain pregnancies for decades.
“The research that we’ve done here has identified progesterone as a significant factor in pregnancies who are at risk for miscarriage or premature labor. We’ve been using it here for three decades safely and effectively, and our outcomes are very good with that,” Kenney told CNA.
She noted that progesterone is routinely used during the in-vitro fertilization process to maintain and support pregnancy, but is not used regularly during typical pregnancies.
“Doctors for years have known how important it is. But in routine pregnancy, it’s really not the standard of care to look at progesterone levels,” she said. “The only time it’s usually done would be in a higher risk situation,” such as when a woman has a history of miscarriages or is bleeding during pregnancy.
The research trial out of the University of Birmingham was conducted on 4,000 pregnant women who had experienced bleeding in early pregnancy – a symptom that can be, but is not always, associated with early miscarriage.
Half of the women were given progesterone supplements and the other half received a placebo. Those who took the progesterone saw a 15% increase in live births.
The study, published in the New England Journal of Medicine, noted that not all the women benefited from progesterone. The greatest benefits appeared to be experienced among women who had previously had three or more miscarriages.
The head of the study told the BBC that he hoped the new data would be used to update national guidelines. Currently, monitoring and supplementing progesterone is not part of standard prenatal care in the U.S. or UK.
Research on progesterone in pregnancy dates back to the ‘40s and ‘50s, Kenney said. Scientists know that progesterone supports the uterine lining to provide a healthy environment for the developing baby.
Dr. Thomas Hilgers, founder and director of the Pope Paul VI Institute, contributed to the existing research on the subject throughout the late 1980s-90s, she said.
“He was trying to look at those high-risk people and figure out what made them high-risk for potentially miscarrying a pregnancy,” she explained. Using the Creighton model of fertility care, a method of fertility awareness and tracking that he had developed, he began to find patterns of abnormality, such as luteal phase deficiency, ovulation problems, and follicular cyst problems, Kenney said. Much of this research was done on women before they became pregnant.
“He found that those patients actually had abnormal progesterone levels” in many cases, Kenney said. “And he surmised that if you treated those patients, you could reduce the risk of miscarriage.”
Hilgers was also able to identify and treat other complications that can contribute to increased risk of miscarriage, such as endometriosis and polycystic ovarian syndrome (PCOS).
His second main area of research was in establishing what constitute normal levels of progesterone throughout pregnancy, Kenney continued.
“He looked at thousands of pregnant women who carried out very, very healthy normal pregnancies, and he looked at their progesterone levels in each week of pregnancy, all the way through the third trimester, to establish a normal range of progesterone levels in pregnancy.”
Hilgers then compared these to pregnancies that were not normal – for example, those that ended in miscarriage or experienced premature labor, placental complications, or fetal distress. He found that pregnancies experiencing poorer outcomes often had lower than normal progesterone levels.
“And so in practice, what we do here at Pope Paul VI Institute is to treat those pregnancies that have lower than normal progesterone in pregnancy, and we reduce the risk of poor outcomes,” Kenney said.
Dr. Kathleen Raviele, an OB-GYN and former president of the Catholic Medical Association, said that if a woman has undergone a miscarriage – particularly very early in pregnancy – she recommends that her progesterone levels be tested following ovulation during a normal cycle. If numbers are low, she recommends supplementing progesterone.
“That seems to be the most effective at preventing subsequent miscarriages if progesterone deficiency is the problem,” she told CNA.
Kenney and Raviele both stressed that there can be many reasons for miscarriage, and progesterone does not solve all problems. Somewhere between 10-25% of pregnancies result in a miscarriage, according to the National Institutes of Health.
“Fifty percent of miscarriages happen because the baby has a chromosomal problem,” Raviele said. “There are also structural problems with a woman’s uterus that can cause miscarriages, infection in the mother, other problems such as diabetes and thyroid disease.”
However, for those patients who do experience low progesterone, offering a simple solution that allows them to carry a healthy pregnancy can be “so healing” for them, she said.
She recalled one woman who came to her after having six consecutive miscarriages. Raviele tested her and found that the woman had a progesterone deficiency. The woman was given supplemental progesterone and had two healthy babies.
“It’s such an easy thing to do, if that’s what the problem is,” Raviele said.
While hundreds of doctors have been trained in Hilgers’ methods, the FDA has never approved the use of progesterone in pregnancy for the prevention of miscarriage. As a result, it is not part of the standard of care followed by most doctors in the majority of pregnancies.
And even if a doctor does decide to test for progesterone in pregnancy, the reference range that is generally used by laboratories is much broader than that established by Hilgers, Kenney said.
“So what we see as suboptimal progesterone is not always what a traditional lab will. We have a lower threshold for treatment because our research has proven that there is a tighter window that progesterone levels should be in pregnancy.”
Raviele said that in her experience, “treatment with progesterone in early pregnancy is very often regional. There are different parts of the country where it’s used frequently, like in the Southeast, and then there are other parts of the country where they don’t have any confidence that progesterone is making a difference.”
But some concerns that are attributed to the use of progesterone are actually the result of the form used and the timing of administering it, she said.
Synthetic progesterone is associated with certain types of birth defects. But the form used by Kenney and Raviele is bioidentical – it perfectly matches the progesterone made by the woman’s body herself, and it does not carry the same risks associated with synthetic versions.
Timing is also important, Raviele said. Beginning progesterone after a woman has already started to show signs that she is miscarrying is not as effective as beginning to supplement with progesterone right after ovulation. Early supplementation can help the baby grow properly and stay implanted in the uterus.
Kenney said that new study out of Birmingham is a hopeful sign. While Hilgers and his colleagues have collected data from thousands of women, there is also a need for randomized, controlled trials, with publications in peer-reviewed medical journals.
“That’s why it’s so important that research get done, and that more evidence like [the Birmingham study] comes out.”
Part of the problem, she said, is that “people have not had a strong interest in the natural physiology – what’s happening in the woman’s body, either in pregnancy or just in the menstrual cycle. So the research has become kind of stagnant in this area.”
“Having a miscarriage is devastating to women. Having repeat miscarriages is more devastating, for women to go through it over and over again,” she added. “So having the ability to say that science has proven that progesterone can decrease your risk of losing a pregnancy is very pro-woman, and we should be investigating this further.”
Kenney said the new study also supports the science behind the abortion pill reversal.
The abortion pill is actually a two-pill regimen. The first blocks progesterone in the woman’s body, and the second, taken 24 hours later, induces contractions to expel the fetus.
Some women experience regret after taking the first pill. Doctors including Hilgers have found that giving women a high dose of progesterone can sometimes override the effects of the initial drug, leading to a normal pregnancy with no increase for health complications.
Critics have argued that the procedure is experimental and lacks scientific basis. However, Kenney said, the new U.K. study “gives validity to the fact that progesterone is the main hormone that supports pregnancy.”
“A medical abortion is just a forced miscarriage. It makes absolute scientific sense that progesterone is the hormone that should be given when you give [women] a medication that basically blocks their progesterone,” she said.
“It’s frustrating to me that these pro-abortion people are saying that this science is completely bogus, when we have studies like this [Birmingham study] that prove the absolute essential nature of progesterone to support and maintain pregnancy.”