This article rounds up the research on the relationship between bacterial vaginosis and fertility. Learn about the symptoms, risk factors, diagnostic methods and treatments available for this condition.

What is bacterial vaginosis, and is it a cause of infertility? In this article, we round up the research to help you make sense of the relationship between this condition and fertility.

Introduction

Many factors play a role in fertility. One of these is the genital microbiota, or the collection of microbes or flora in the genital tract. In particular, the female genital microbiome is associated with fertility, and disturbances in it are sometimes related to infertility.

Bacterial vaginosis (BV) is characterised by a disturbance of the vaginal microbiome. In this article, we will take you through what BV is, its diagnosis and treatment, and how it might impact fertility and attempts to conceive.

Definition

Bacterial vaginosis is the most common genital tract infection among women of reproductive age. While its prevalence is found to vary by study and by geographical location, one estimate is that 1 in 4 women of reproductive age around the world has the condition. Many women will thus be affected by BV during their lifetimes.

BV results from an imbalance of vaginal flora, with too little of the lactobacilli that are usually dominant in a healthy vagina. At the same time, there is an overgrowth of opportunistic bacteria such as Gardnerella vaginalis, which can have harmful effects, including the symptoms that characterise BV. In addition, there is an increased risk of sexually transmitted infections, such as HIV, chlamydia, gonorrhea, and human papillomavirus (HPV) with BV; this is thought to be related to the alterations in pH level that accompany the condition.

Symptoms

In about half of all cases, women with BV experience symptoms, including

  • A foul, 'fishy' odour
  • Itching of the vagina or vulva
  • Unusual vaginal discharge that may be grey or white and thin or watery
  • Burning with urination

The other half of affected women do not experience any symptoms.

Risk Factors

Despite many years of research, the cause of BV remains challenging to pin down. Researchers have, however, been able to identify some risk factors related to BV:

  • Increased number of sex partners and certain sexual practices, including non-coital sexual practices
  • Lack of genital hygiene or infrequent change of underwear
  • Douching or washing the vagina. It is possible, however, that douching does not cause BV but that women opt for douching in response to symptoms of BV that they experience.
  • Recent use of broad-spectrum antibiotics, which can affect vaginal flora, reducing the number of lactobacilli
  • Sexually transmitted diseases, or STDs
  • Cigarette smoking
  • Certain contraceptive methods, such as disposable intra-uterine devices
  • Stress

It has also been found that oral contraceptives may protect against BV.

Diagnosis

Two main methods have been traditionally used to diagnose BV. One of these, known as Amsel’s criteria, involves checking for the following:

  • Watery or milky discharge characteristic of BV;
  • Higher-than-normal vaginal PH;
  • 'Fishy' odour when a sample of discharge is combined with a 10% potassium hydroxide solution (known as a positive 'whiff test'); and
  • Whether a sample obtained via vaginal swab reveals so-called 'clue cells' when examined under a microscope.

By contrast, the Nugent score relies on a laboratory test known as a gram stain. While the Nugent score is considered the best or 'gold-standard' technique and is often used in research settings, it is also a more complex technique, so the Amsel criteria are more often used for diagnoses in clinical settings. In addition, new molecular tests, such as those based on polymer chain reaction (PCR) technology, are also increasingly being used.

Medical Treatment

It’s important to treat bacterial vaginosis for a few reasons. To begin with, BV can come with bothersome symptoms. Apart from this, BV is associated with specific fertility and pregnancy complications, such as very early loss of pregnancy (also called a preclinical pregnancy loss) and preterm delivery, as we discuss further below. It also increases the risk of contracting sexually transmitted diseases (STDs), including HIV, gonorrhea, chlamydia trachomatis, and herpes. In addition, it is associated with pelvic inflammatory disease (PID) and vaginal yeast infections. These conditions can have a negative impact on health and fertility.

Treatment of bacterial vaginosis is typically done with antibiotics, such as metronidazole or clindamycin, which are either taken by mouth or used in the preparation (such as a cream or gel) that can be inserted into the vagina.

Due to a lack of structured studies and conflicting findings, it is difficult to definitively say that these treatments are safe for pregnancy or breastfeeding. Therefore, if you are pregnant, planning to get pregnant, or breastfeeding, it is best to consult your fertility specialist prior to beginning this antibiotic treatment.

While treatment tends to be effective, with most cases of BV resolving after antibiotics, a challenge is that BV tends to recur. Within one year after effective treatment of BV, up to 50% of women will have the condition again. Although there are no studies yet to prove this, not taking all doses of antibiotic treatment is a possible contributor to this recurrence.

Another factor could involve a 'biofilm' that BV-associated bacteria can form, protecting the harmful bacteria from the antibiotics. It is also thought that sexual partners of either sex may be able to reinfect individuals who have been treated effectively: studies show that the microbiome of the penis and male urethra can show changes that correspond to those in BV. Whether male partners of women with BV should also be treated has not yielded convincing evidence and is still being investigated.

Probiotics are also sometimes used to prevent BV from recurring. Similar to the antibiotics for BV, these can be taken by mouth or intravaginally. They may be helpful because while antibiotic treatment works to eliminate the harmful bacteria that characterise BV, it can also reduce the levels of lactobacilli, the bacteria that generally dominate the vaginal microbiome and help to ensure its health. Probiotics containing lactobacilli can thus help to restore the average balance of vaginal flora. They can be started at the same time as antibiotics or after antibiotic treatment. Studies on probiotics as supplemental treatment are promising. Still, they have also tended to be minor and to differ in terms of which probiotic is used and in what timeframe.

Lifestyle Treatment

Several lifestyle factors may also help to prevent bacterial vaginosis from occurring or recurring. These include avoiding douching, which is not recommended even for women without BV, changing underwear frequently, and wearing breathable underwear made of cotton to reduce moisture and the growth of harmful bacteria. Avoiding smoking may also reduce the risk of BV. Lastly, condom use is also recommended to prevent reacquiring the condition from a partner.

Impact on Fertility

The scientific evidence gathered so far shows that bacterial vaginosis is more common in infertile women compared to women without fertility problems. In particular, BV is associated with tubal infertility, in which an egg and sperm cannot meet due to blockage of the fallopian tubes. However, there is also some evidence that BV may also be related to idiopathic fertility (infertility that has no known cause). A 2013 meta-analysis combining the evidence from 12 studies with a total of 3,229 patients found that women experiencing infertility were significantly more likely to have BV than pregnant women. Despite this finding, BV was not associated with decreased overall conception rates and was not found to impact conception via in vitro fertilisation (IVF).

The above meta-analysis also combined the available evidence on pregnancy loss with BV. Based on five studies, it was found that women with BV were significantly more likely than women without BV to experience 'preclinical' pregnancy loss (defined as that which occurred before the pregnancy could be detected by either a missing period or an ultrasound). By contrast, no significant association was found between BV and pregnancy loss in the first trimester.

Lastly, there is evidence that bacterial vaginosis is also linked to preterm birth and low birth weight before 37 weeks of gestation. It is unclear whether treating BV with antibiotics helps reduce this risk.

Also important to consider is that BV is associated with certain sexually transmitted diseases, postpartum endometritis (an inflammation of the uterine lining), and pelvic inflammatory disease (PID), which can have their own, often harmful, impact on fertility. It may also be the case that BV can affect male fertility. However, the evidence regarding this is not yet sufficiently strong.

Given the above evidence that bacterial vaginosis impacts fertility, women experiencing infertility may wonder if they should be tested for BV, even without symptoms. Similarly, pregnant women may become concerned about the association with preterm delivery. Current guidelines recommend that only women experiencing symptoms of BV should be tested. However, you should talk with your care provider or fertility specialist if you are concerned about this topic.

Commonly Asked Questions

If I have bacterial vaginosis, will it go away on its own?

In some cases, BV does resolve on its own. Often, however, individuals will be prescribed either oral or intravaginal antibiotics to help clear the vaginal infection.

How can I prevent bacterial vaginosis from returning if I’ve had it?

Suppose you are prescribed antibiotic treatment for BV. In that case, you should take all days and doses, even if you experience relief from your symptoms, before the treatment is finished.

You can also consider lifestyle changes, like wearing breathable cotton underwear, washing the genital area with mild, fragrance-free soap, and using condoms.

Lastly, ask your healthcare provider about probiotics to prevent BV from recurring.

Is bacterial vaginosis a sexually transmitted infection? Can I get it from my partner?

It’s important to note that BV is not an STI: the primary method of contracting it is not through a partner. However, researchers have indicated that the microorganisms involved in BV can be carried by male partners, who may also reinfect women following treatment.

Should my partner be treated if I have bacterial vaginosis?

The answer to this question is unclear due to mixed evidence in the past and ongoing research. Currently, there are no guidelines for treating the partners of women with BV.

Takeaway

Bacterial vaginosis (BV) is a common genital tract infection among women of reproductive age. Women with BV may have symptoms, such as unusual discharge, odour, or itching, or they may be asymptomatic. Typically only women with symptoms are tested and treated. Treatment of BV, usually based on antibiotics, is generally quite effective, but a challenge is that the condition can recur. Lifestyle changes and probiotics may help prevent this recurrence.

Research shows that more women with infertility are found to have BV and that preclinical loss of pregnancy and preterm delivery is more likely to occur in women with BV. However, BV does not seem to affect the overall chances of conception. Research is still being conducted into various aspects of bacterial vaginosis and its treatment, such as whether the male partners of women with BV should also be treated.

At Cada, our caring team puts individuals at the centre of their fertility care. Would you like to discuss this issue or other issues concerning reproductive health and fertility? Please get in touch with us so that we can figure out how best to help you. Reserve your spot for a free consultation today.