Can BV Cause Miscarriage?

Written by Kathleen Morrison
Medically Reviewed by Andrea Sleeth WHNP-BC, MSCP

Key takeaways

• Bacterial vaginosis is associated with an increased risk of pregnancy complications, including miscarriage in the first and second trimesters.
• Women with bacterial vaginosis may have a higher risk of early pregnancy loss compared to women with normal vaginal flora.
• BV is treatable, and screening and treatment early in pregnancy may help reduce the risk of complications.
• Symptoms of bacterial vaginosis include unusual vaginal discharge with a fishy odor, though many cases are asymptomatic.
• If you're pregnant or trying to conceive, talking to a healthcare provider about BV screening can help support healthy pregnancies.

If you're pregnant (or trying to conceive) and dealing with bacterial vaginosis, you might be wondering: Can BV actually cause miscarriage?

It's a totally valid concern, and honestly, one that doesn't get talked about nearly enough.

Here's what you need to know: bacterial vaginosis is one of the most common genital tract infections among women of reproductive age, and research suggests it may be linked to pregnancy loss and other obstetric complications.

But before you spiral, let's break down what the science actually says, what symptoms to look for, treatment options to consider, and how to protect yourself and your pregnancy.

Wisp treatment options are available only after consultation with a licensed medical professional. You should consult with your healthcare provider before starting a new supplement or treatment regimen. Individual results may vary.

*Wisp does not provide BV treatment during pregnancy. If you’re pregnant or think you might be, an in-person health care provider or OB-GYN is the best next step.

What is bacterial vaginosis (BV)?

Bacterial vaginosis (BV) happens when the natural balance of bacteria in your vagina gets disrupted. Think of your vaginal microbiome like a garden where good bacteria keep everything healthy by maintaining an acidic environment.

When harmful bacteria multiply too quickly, they overtake the lactobacillus bacteria (the good ones), creating a bacterial imbalance that leads to BV.

Bacterial vaginosis and pregnancy risks: How are they interlinked?

Your vaginal environment isn’t fixed. It shifts throughout your menstrual cycle and across different life stages.

Pregnancy is one of the biggest hormonal changes your body goes through, hormonally speaking, so it makes sense that your vaginal balance can shift too.

During pregnancy, rising estrogen levels can change vaginal pH. When that environment becomes less acidic, it’s easier for harmful bacteria to grow, increasing the likelihood of developing bacterial vaginosis (BV).

Why your vaginal microbiome matters (a lot)

Your vaginal microbiome is usually doing the most behind the scenes. Healthy bacteria produce lactic acid and hydrogen peroxide, which:

• keep the vaginal environment healthy and acidic
• help block harmful bacteria from multiplying
• protect against bacteria moving upward into the uterus

When BV disrupts this balance, that protection weakens.

What happens when BV disrupts the balance?

When BV is present, a cascade of changes can occur:

• The vaginal environment becomes less acidic
• Harmful bacteria multiply more easily
• Inflammation may develop in the genital tract
• Inflammatory substances like prostaglandins may be released, potentially leading to cervical changes

This is where BV becomes more than “just” a vaginal infection.

Can BV increase the risk of miscarriage?

Research suggests bacterial vaginosis is associated with an increased risk of miscarriage.

This is likely due to reduced protective Lactobacillus species and an overgrowth of anaerobic bacteria, including Gardnerella vaginalis.

Overall, BV is associated with an approximately 2–3-fold increased risk of spontaneous abortion.

And, while G. vaginalis (overgrowth of bad bacteria) is a major component of BV, the increased risk does not appear to be driven by high levels of G. vaginalis alone.

Instead, the association is linked to overall vaginal dysbiosis and the body’s inflammatory response.

What research points to most consistently is this:

• The loss of protective Lactobacillus species is a stronger and more reliable predictor of pregnancy loss
• This imbalance may contribute to cervical changes, rather than any single pathogenic bacteria acting on its own

The point is, it’s the ecosystem shift (not one bad actor) that matters most.

Timing and its role in BV-related risks during pregnancy

Timing can matter when it comes to BV during pregnancy, but the pattern isn’t always straightforward.

Some research suggests the risk of certain complications may be higher if BV happens in the first trimester, while other studies have also found a possible increased risk during the second trimester.

In women with previous preterm delivery or other risk factors for preterm birth, early-pregnancy BV detection is associated with elevated preterm birth and late miscarriage risk.

At the same time, plenty of women with BV go on to have totally healthy pregnancies, especially when it’s caught and treated early.

That said, major clinical guidelines don’t recommend routine BV screening if you’re low-risk and not having symptoms, either before or during pregnancy.

The wise move? Listen to your body and loop in your healthcare provider if anything feels off, so they can check it out and treat it if needed.

BV complications during pregnancy: beyond miscarriage

The risks associated with bacterial vaginosis in pregnancy extend beyond the risk of miscarriage. These include:

• Preterm birth: BV has been linked to premature birth (delivery before 37 weeks). The infection may trigger an inflammatory response that could lead to early labor.
• Low birth weight: Babies born to women with untreated BV may have a higher risk of low birth weight, which can affect fetal development.
• Premature rupture of membranes: When BV bacteria produce enzymes that weaken the amniotic sac, your water can break too early—before 20 weeks or later in pregnancy.
• Pelvic inflammatory disease: Untreated vaginal infections can sometimes lead to more serious infections affecting the reproductive organs.
• Increased STI risk: The vaginal inflammation from BV can make you more susceptible to sexually transmitted infections, including chlamydia.

These potential complications are one of the common causes of why paying attention to your vaginal health during pregnancy matters so much.

When BV poses the greatest risk

First and second-trimester BV pose the highest overall risk for miscarriage. During these crucial weeks, your baby's major organs form and the placenta establishes itself.

Women with BV early in pregnancy may face not only increased miscarriage risk but also higher chances of complications that manifest later.

Certain risk factors may amplify the effects of BV during pregnancy, including:

• a history of preterm birth
• smoking (which alters vaginal pH)
• diabetes
  

How is BV treated during pregnancy to reduce miscarriage risk?

Here's the good news: bacterial vaginosis is highly treatable, and treating BV early may help reduce the risk of pregnancy complications.

The standard treatment for bacterial vaginosis involves a course of antibiotics that are considered safe during pregnancy.

Your provider may prescribe:

• Metronidazole: This can be prescribed as an oral medication or vaginal gel. Metronidazole can effectively help eliminate harmful bacteria while maintaining a strong safety profile during pregnancy.
• Clindamycin: Another antibiotic option is clindamycin. It is particularly useful as a vaginal cream for pregnant women experiencing nausea.

Treatment typically lasts 7 days, and it's important to complete your full course of antibiotics even if symptoms improve.

Your healthcare provider will determine the best prescription based on how many weeks pregnant you are and your overall health history.

Side effects you should know about

While both metronidazole and clindamycin are highly effective for tackling bad vaginal bacteria causing BV, they come with side effects (that are usually mild and temporary).

Metronidazole:

• Upset stomach or cramps, nausea and vomiting, and loss of appetite can occur (more typical with oral dosing)
• A metallic or unpleasant taste in the mouth and dry mouth
• Diarrhea can happen
• Rare but more serious effects can include allergic reactions, severe stomach pain, or blurred vision. Seek care promptly if these show up

Important precaution: Avoid alcohol while taking metronidazole, as it can cause a disulfiram-like reaction. This may include flushing, nausea, vomiting, headache, rapid heartbeat, and shortness of breath.

Clindamycin:

• Vaginal irritation/burning/itching
• Mild GI effects can occur (nausea, abdominal discomfort)
• Risk of C. difficile–associated diarrhea, a potentially serious intestinal infection linked to antibiotic use. Symptoms may include persistent watery diarrhea, abdominal cramping, or fever. Seek medical care promptly if these occur.
• Allergic reactions (hives, swelling, breathing difficulty)

This is not a complete list of risks and side effects, and others may occur. If symptoms worsen or you notice signs of an allergic reaction, contact a provider right away.

Supporting your vaginal health before and during pregnancy

Taking proactive steps can significantly help support a healthy vaginal environment:

• Skip the douches and scented products: Your vagina is self-cleaning. Harsh soaps can disrupt your natural bacterial balance.
• Wear breathable underwear: Cotton helps keep things dry and reduces environments where BV-causing bacteria flourish.
• Practice safe sex: Using condoms can help maintain vaginal pH balance.
• Stay on top of symptoms: If you notice any unusual vaginal discharge or odor, don't wait to get checked out.
• Consider probiotics: Probiotics can help support vaginal health, though they shouldn't replace treatment for active infection.

If you're trying to conceive, getting tested 3-6 months before pregnancy allows time for BV treatment if needed, plus time to confirm the infection has cleared.

Your vaginal health, your call (especially during pregnancy)

Here's the thing: bacterial vaginosis is incredibly common, and it doesn't have to derail your pregnancy plans.

The key is awareness, early detection, and treatment when needed.

If you're experiencing symptoms or just want peace of mind, it's worth getting checked out, especially if you're pregnant or trying to conceive.

Wisp makes it easy to get the care you need for bacterial vaginosis without the awkward in-person waiting room experience—for people who are not pregnant or actively trying to conceive.*

Not sure what's going on? Our symptoms quiz can help you figure out your next steps.

*Wisp does not provide BV treatment during pregnancy. If you’re pregnant or think you might be, an in-person health care provider or OB-GYN is the best next step.

This blog post is for informational and educational purposes only and should not be taken as professional advice. Always consult with a qualified professional before making any decisions based on the information provided here.