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3 Potential Causes of Miscarriage


**Trigger Warning: This blog discusses miscarriage and pregnancy loss.**


If you’re trying to conceive, you may be wondering what you can do to increase your chances of a healthy, full-term pregnancy. This is a big topic, and you should always discuss your particular risk factors with your healthcare provider. 

However, there are a few common causes of miscarriage and pre-term birth that you can take action on, before you conceive, so we’ve partnered with Juno Bio to dive into your options.

Miscarriage – let’s talk about it

A miscarriage is the loss of a pregnancy before the 20th week of gestation. 80% of miscarriages occur during the first trimester. Miscarriage is incredibly common, even if it isn’t talked about all that much. It’s estimated that over one-quarter of pregnancies end in miscarriage. Fortunately, women can usually go on to have a successful pregnancy following a previous miscarriage.

Most miscarriages are caused by chromosomal abnormalities, and aren’t the result of anything the parents did or didn’t do. If you’re trying to reduce your risk of miscarriage, though, and for peace of mind when TTC, there are a few common causes of miscarriage that you CAN do something about now. 

1. Vaginal dysbiosis and infection

One common cause of miscarriage is infection caused by imbalance (dysbiosis) in your vaginal microbiome, or the community of microbes naturally living in your vagina. A healthy vaginal microbiome is typically dominated by a type of good bacteria called Lactobacillus, and it protects you against infections. 

It is a carefully balanced ecosystem - when the balance is disrupted it can lead to infections like bacterial vaginosis (BV). This is definitely something to keep an eye on, as preventable infection accounts for up to 15% of early miscarriages (before 12 weeks) and 66% of late miscarriages (12 weeks or later). The majority of late miscarriages are caused by harmful microbes ascending from the vagina through the cervical canal into the uterus. Here the microbes can infect the amniotic fluid and the developing fetus. 

Many bacteria associated with miscarriage can be found in the vagina without causing symptoms. For example, bacterial vaginosis (BV), characterized by low levels of Lactobacillus and high levels of other anaerobic bacteria, can increase your miscarriage risk but is often asymptomatic. Since treatment of asymptomatic BV in pregnant women isn’t usually recommended due to the possible effects of antibiotics on the baby, it’s worth checking on before you get pregnant so it can be treated if needed. 

Chronic endometritis (CE; infection of the uterine lining) is another infection associated with miscarriage, and successful treatment of CE with antibiotics has been shown to improve pregnancy outcomes in cases of multiple miscarriages. However, it too is often asymptomatic or overlooked due to mild symptoms.

You may be wondering, if these infections can be asymptomatic, how would I know about them? If you are planning a pregnancy it is great to check on your vaginal microbiome to rule out dysbiosis as a potential risk factor for adverse pregnancy outcomes. Fortunately, vaginal microbiome testing can be easy and cost-effective. 

Juno Bio provides a simple, non-invasive vaginal microbiome test that you can take from the comfort of your own at home. You can buy a single test kit with $20 off using this link, or you can subscribe for a discounted test every three months. For more information about the vaginal microbiome and its importance in over 30 female health conditions, check out the Juno Bio websiteJunoBio provides a simple, non-invasive microbiome test that you can take from the comfort of home.

If you do happen to have vaginal dysbiosis, it’s wise to test regularly to see the effect that your treatments are having. It’s a carefully balanced ecosystem and there are many ways your microbiome can respond to treatment. Not only that, treatments that were not intended to act on your microbiome can still impact your vaginal flora. Regular testing allows you to track recovery and adjust treatments accordingly.

2. Viral Infections

Another common preventable cause of miscarriage is viral infection. While you can’t prevent exposure to every virus, there are a few viral infections that increase risk of miscarriage that can be easily screened for (or your immunity can be tested). These include: 

  • Rubella: A flu-like illness, usually with a rash, that has severe complications in pregnancy. While rubella is extremely rare in the US, it is more common in some parts of the world and puts pregnant women at very high risk of miscarriage.
  • HIV (human immunodeficiency virus): Even in asymptomatic HIV+ individuals, risk of miscarriage was over 50% according to one study. It’s important to be screened for HIV, and if you are HIV+, talk to your doctor about your TTC plans. 
  • Hepatitis B and C: Viruses that cause liver disease and may increase risk of miscarriage especially in chronic infections, although some studies are contradictory.

Simple blood tests can screen for the presence of these viruses in your system, as well as test your immunity level. While people in the US are wildly vaccinated against many of these viruses, immunity can decrease over time and it’s worth checking. Many doctors already include screening for these viruses in the workup once you get pregnant, but if you’re TTC, it’s a good idea to ask to have that done before you’re actually pregnant so that if you need to be revaccinated or treated, you can be. 

3. Low progesterone or hormonal imbalance

Hormones are involved in all parts of the TTC journey, and preventing miscarriage is no exception. Progesterone in particular is important in successful implantation and healthy pregnancy, and there are many reasons you may have low progesterone or other hormonal issues impacting the health of a pregnancy. 

Progesterone is the hormone that rises in the second half of the cycle after ovulation, and is responsible for preparing the uterine lining for the implantation of a new embryo. If progesterone levels are not sufficient, you may have challenges getting pregnant at all, but even if you do, low progesterone production can cause failed implantation or early miscarriage. 

Low progesterone can cause many symptoms including short menstrual cycles, mood swings, and spotting, but for some women the only symptom may be difficulty getting pregnant or early miscarriage. There’s hope, though, as studies have shown that progesterone supplementation can reduce the risk of miscarriage in many women. 

Even if you aren’t having symptoms of low progesterone, you can easily test progesterone during the implantation window to ensure that you’re giving a new embryo the best chance of successfully implanting and reducing risk of early miscarriage. As an added bonus, testing progesterone will help determine if you’re ovulating successfully, which is a must when TTC! 

There are two main ways to test progesterone – you can have a blood draw done at your doctor’s office, or you can test pregnanediol glucuronide (PdG), a metabolite of progesterone found in urine. PdG testing with Proov Confirm can be done easily at home, and tests PdG during days 7-10 after ovulation, not just a single day like a blood draw.

Testing PdG with Proov checks for successful ovulation, meaning PdG levels remained elevated for the entire 7-10 day window after ovulation. A recent clinical study showed that elevated and sustained PdG levels during the implantation window increases pregnancy rates by over 75%.

If you discover that you have low progesterone, you have a few options to try to improve your levels naturally. These include: 

  • Diet and nutrition: Malnutrition or an unhealthy diet can impact hormone levels, so try reducing sugar and processed foods, and stick to lean protein, healthy fats, and lots of greens to promote hormonal balance. You can also try Seed cycling, or adding certain seeds to your diet during the different phases of your cycle.
  • Herbal supplements: Herbal supplements such as maca, vitex, and ashwagandha support progesterone production and hormonal balance. Proov Pro is a great way to add these into your routine.

If you have tried these methods and are still experiencing low progesterone levels, consult your medical provider or consider trying Proov Path to Pregnancy. You may be a good candidate for prescription-strength progesterone support and help get to the cause of your low progesterone. 

Overall, while the majority of miscarriages unfortunately aren’t preventable, you can reduce your risk by testing your vaginal microbiome, screening for viral infections and immunity, and testing PdG levels. We know it can feel like a lot, so Proov and Juno Bio are in your corner for your TTC journey!

Written by: Ruth Richards. Ruth is a computational biologist at Juno Bio where she leads the development of their metagenomics discovery platform.

3 potential causes of miscarriage

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