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Can low progesterone cause miscarriages?

Can low progesterone cause miscarriages?

Chanel Dubofsky | June 15, 2021 | Getting Pregnant
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Hormones play an important role in pregnancy. It's your hormones, after all, that dictate the regularity of your menstrual cycle, including ovulation, the release of an egg from an ovary. After that egg is released, your body prepares for the possibility of it being fertilized by a sperm and producing an embryo, and therefore, a pregnancy. The hormone that's produced to support that pregnancy? Progesterone (1). 

Progesterone's many jobs

Progesterone triggers the endometrium that's the mucous membrane lining the uterus to thicken so that if the egg is fertilized, it can implant and develop (2). Progesterone prevents the contraction of the uterine muscles that could expel a pregnancy. It also suppresses your immune system so it doesn't reject the pregnancy, which may be recognized as a foreign invader. In later stages of pregnancy, progesterone continues to press pause on ovulation and encourages milk production for breastfeeding. That's a lot of heavy lifting for one hormone! 

Progesterone levels fluctuate throughout your menstrual cycle. They often remain low (1.5 ng/mL) during the follicular stage, the time between the first day of your period and ovulation (3). After you ovulate, your progesterone levels go up and stay up for about 5 days, then go back down. Progesterone levels also rise from week 9 of pregnancy until week 32. 

Indications of low progesterone include long or heavy periods, spotting before your period, irregular menstrual cycles, and short menstrual cycles (4). Because progesterone plays such an enormous role in sustaining pregnancy, many people don't know they have low progesterone levels until they have trouble getting pregnant (irregular periods make it difficult to track ovulation), or they've had multiple miscarriages. 

Does low progesterone cause miscarriage?

Science actually doesn't know that answer yet. Researchers and doctors still have more to learn about progesterone and its exact role in miscarriages. Being low in progesterone doesn't mean you're guaranteed to have a miscarriage and it's actually not entirely known if low progesterone leads to miscarriage, or if miscarriages caused the low progesterone levels (5). 

"We know that successful pregnancies tend to have higher levels of progesterone and abnormal pregnancies tend to have lower levels, but there is no cut-off point that we can use to determine whether a pregnancy will result in a healthy live-born infant," says Dr.  Thomas Molinaro, a reproductive endocrinologist at the RMA Network in New Jersey. 

"Abnormal pregnancies may turn out to be miscarriages or tubal (ectopic) pregnancies." 

Dr. Amy Beckly, PhD advises that if you're having trouble conceiving, you've had a pregnancy loss, or you have a family history of pregnancy loss, you should consider getting your levels checked. Dr. Beckly endured several miscarriages and years of infertility before confirming that she indeed had a progesterone problem — specifically luteal phase defect, which occurs when your body doesn't produce enough progesterone to thicken the endometrium and maintain pregnancy. (6)

Does spotting and bleeding during early pregnancy mean I have low progesterone?

Light bleeding and/or spotting happens to 15-25% of women in the first trimester. This can be due implantation bleeding (when the fertilized egg implants in the uterus) and/or because the cervix may bleed more easily due to developing more blood vessels during this time (7). This type of bleeding (light bleeding and/or spotting) early in pregnancy is common and in most cases, typically nothing is wrong, according to the American College of Obstetricians and Gynecologists (8). Regardless, you should let your healthcare provider know immediately and keep track of any type of bleeding. 

If you previously experienced a miscarriage, or are worried about the possiblity of a miscarriage, Beckly says it perfectly: “Just because [bleeding] happens doesn't mean you have to accept it. Doctors are experts in medicine, but you are an expert on yourself." (Click here to read how Amanda identified low progesterone and saved her pregnancy with Kindara.) If you're bleeding, Beckley recommends getting blood tests to evaluate both your HCG (that's the pregnancy hormone, which should be doubling every 48 hours) and progesterone levels, to make sure they aren't falling. 

"You need to have the right amount of progesterone before ovulation, so it can prepare the uterus to receive the embryo," says Dr. Beckley. A blood test can check your levels of progesterone, but because your progesterone levels fluctuate throughout the day, and throughout your cycle, "a single blood draw isn't a good diagnostic measure," she points out (8).

You can bring those results to your doctor so you can discuss your next move together. Since progesterone levels change throughout pregnancy you may need to be retested several times (9). The more information you have, the more informed your doctor will be to treat your individual situation. 

How is low progesterone treated?

"Progesterone is typically given as a vaginal suppository or an intramuscular injection in order to achieve the levels that would promote a pregnancy," says Molinaro. 

While some doctors will prescribe progesterone supplements to patients whether or not they're low in order to ensure that the pregnancy is supported, others hesitate to do so because they're skeptical of their efficacy. A 2016 study suggested that live birth rates increased by only 2% when given progesterone supplements, but the progesterone was administered after the embryo was already implanted and the pregnancy confirmed. 

Since progesterone is needed to prepare the uterus for implantation, it is thought to be  basically too late for the supplement to be impactful (10). However, in a 2017 study of the effects of progesterone on recurrent pregnancy loss, progesterone was given at the start of the luteal phase before fertilization occurred, and the live birth rate was 17% (11). 

To treat low progesterone effectively, it's important to know why it's happening. If you have an underlying condition like polycystic ovary syndrome (PCOS) or hypothyroidism, both of which can cause low progesterone, it needs to be addressed. Otherwise, says Beckley, "Supplements are just a band-aid." 

References +

Progesterone and Progestins. (2019, October). Retrieved October 7, 2020 from https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/progesterone


What Does Progesterone Do? (10 October 2020). Retrieved October 11, 2020 from https://proovtest.com/blogs/blog/what-does-progesterone-do


Common misconceptions about progesterone after ovulation. (04 April, 2020). Retrieved October 11, 2020 from https://proovtest.com/blogs/blog/misconceptions-progesterone


Progesterone 101. (27 May 2019). Retrieved October 7, 2020 from https://helloclue.com/articles/cycle-a-z/progesterone-101


Pilot Evaluation of a New Urine Progesterone Test to Confirm Ovulation in Women Using a Fertility Monitor. (Published online 2019 Jul 2). Retrieved October 11, 2020 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6614355/


Bleeding During Pregnancy. (2019 September). Retrieved October 11, 2020 from https://www.acog.org/patient-resources/faqs/pregnancy/bleeding-during-pregnancy


How Does Low Progesterone Affect Pregnancy? (07 April, 2020). Retrieved October 14, 2020 from https://www.whattoexpect.com/pregnancy/your-health/low-progesterone-pregnancy/

9 Efficacy of progesterone supplementation during early pregnancy in cows: A meta-analysis. (2016 May). Retrieved October 11, 2020 from



Luteal start vaginal micronized progesterone improves pregnancy success in women with recurrent pregnancy loss. ( 2017 January 09). Retrieved October 11, 2020 from https://www.fertstert.org/article/S0015-0282(16)63029-7/fulltext


Progesterone Test. (n.d.). Retrieved October 19, 2020 from https://medlineplus.gov/lab-tests/progesterone-test/

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