Bacterial Vaginosis (BV) is a common vaginal infection that often raises concerns, particularly during pregnancy. This article provides clear, evidence-based information on bacterial vaginosis, its characteristics, and its relationship with first-trimester miscarriage. Understanding this condition is important for pregnant individuals and those planning conception.
Understanding Bacterial Vaginosis
Bacterial vaginosis is a prevalent vaginal infection resulting from an imbalance in the natural bacterial environment of the vagina. A healthy vagina typically contains a balance of various bacteria, with lactobacilli usually dominating. When other bacteria, such as anaerobes, overgrow and outnumber the beneficial lactobacilli, BV can develop. This shift disrupts the vagina’s natural chemistry and pH balance.
While BV is not considered a sexually transmitted infection (STI), it is more common in sexually active individuals. Symptoms, when present, can include a thin, off-white, gray, or greenish vaginal discharge, a strong “fishy” odor that may be more noticeable after sex, and sometimes vaginal itching or a burning sensation during urination. However, up to 84% of individuals with BV may not experience any symptoms, making it an asymptomatic condition for many.
BV and First Trimester Miscarriage
Most first-trimester miscarriages, accounting for about half to two-thirds of cases, occur due to chromosomal abnormalities in the developing fetus. These genetic issues prevent the embryo from developing properly and are largely beyond a person’s control.
Regarding BV, some studies suggest a potential link between untreated BV and an increased risk of adverse pregnancy outcomes, such as late miscarriage or preterm birth. However, the evidence specifically for a direct causal link between BV and first-trimester miscarriage is less conclusive and can vary across research. For example, one study involving women undergoing in vitro fertilization found a significantly increased risk of first-trimester miscarriage in those with BV, suggesting a twofold higher risk compared to those with normal vaginal flora.
Conversely, other studies have found no statistically significant relationship between BV and first-trimester miscarriage. While BV can be a risk factor for certain pregnancy complications, its direct impact on very early pregnancy loss is not universally established as a primary cause. The overall risk, if any, is generally considered low, but diagnosing and treating BV during pregnancy remains important for overall maternal and fetal health.
Diagnosis and Treatment of BV in Pregnancy
Diagnosing bacterial vaginosis during pregnancy typically involves a healthcare provider’s examination and laboratory tests. A physical exam may reveal characteristic vaginal discharge. The provider can take a vaginal swab to analyze the fluid microscopically for “clue cells,” which are vaginal cells covered in bacteria, a hallmark sign of BV.
Additional diagnostic steps often include testing the vaginal pH, as a pH of 4.5 or higher can indicate BV, and performing a “whiff test,” where a fishy odor is detected after adding a specific solution to the vaginal discharge. Once diagnosed, BV is primarily treated with antibiotics, which are generally considered safe and effective during pregnancy. Common antibiotic options include oral or vaginal forms of metronidazole or clindamycin.
It is important to complete the full course of prescribed medication, even if symptoms improve or disappear, to ensure the infection is fully cleared. While some sources indicate caution with metronidazole in the first trimester, the Centers for Disease Control and Prevention (CDC) recommends treatment for symptomatic pregnant individuals with BV. For pregnant individuals at high risk for preterm delivery, screening and treatment for BV are also often recommended.
Preventive Measures for BV
Several measures can help maintain vaginal health and potentially reduce the risk of developing BV or its recurrence.
Avoid douching, as it can disrupt the natural balance of bacteria in the vagina and increase the risk of infection. The vagina is naturally self-cleaning and does not require internal washing.
Use mild, unscented soaps for external genital hygiene and avoid perfumed products, such as scented tampons, sprays, or bubble baths.
Wear breathable underwear, preferably cotton, to reduce moisture buildup.
Practice safe sex, including consistent condom use and limiting the number of sexual partners.
Wipe from front to back after using the toilet to prevent the transfer of bacteria from the anus to the vagina.