Vaginitis is extremely common. Its symptoms account for millions of physician visits each year. Moreover, common infectious forms of vaginitis are associated with several public health issues. Notably, pregnant women with some forms of vaginitis are at increased risk of premature labor and preterm delivery. Certain vaginal infections also increase susceptibility to sexually transmitted infections, including HIV.
NICHD research aims to better understand the various types of vaginitis. Researchers are investigating the biological and behavioral factors that contribute to the development of these various types of vaginitis. Researchers aim to clarify the role of vaginal infections in adverse pregnancy and other health outcomes and to explore protective factors and interventions that might preserve vaginal health and prevent morbidities.
The long-term objectives of NICHD research related to vaginitis are to reduce rates of vaginitis and the burden of bothersome symptoms and associated adverse health outcomes. To this end, NICHD-supported studies focus on the following:
Epidemiology of Vaginitis
NICHD research efforts aim to identify and to understand behavioral and biological factors that increase susceptibility to vaginitis and contribute to its remission. Studies also are looking at the various aspects of the association between vaginal infections and pregnancy complications.
Pathogenesis and Microbiology
The normal vaginal microenvironment is dominated by several Lactobacillus species that protect against overgrowth of endogenous bacteria and infectious pathogens. NICHD scientists are studying the vaginal flora, the protective actions of these Lactobacilli, and the mechanisms by which flora imbalances occur and infections arise.
Scientists supported by the NICHD are pursuing formative research for the development of interventions to protect against vaginitis.
Through its intramural and extramural organizational units, the NICHD conducts and supports a broad range of research on vaginitis and related conditions. Brief descriptions of this research are included below.
Institute Activities and Advances
Bacterial Vaginosis (BV)
NICHD researchers within the Division of Population Health Research (DiPHR) are using previously and newly collected data to study various aspects of abnormal genital tract flora. The project's purpose is to explore various aspects of the association between BV and pregnancy outcome and to understand the various behavioral and biological factors associated with the acquisition, maintenance, and remission of BV.
Previously collected data sets include the Vaginal Infections and Prematurity Study (1984–1989), in which approximately 14,000 pregnant women had detailed genital tract microbiological evaluations done at 23 to 26 weeks' gestation, answered detailed questionnaires, and had a variety of pregnancy outcomes assessed.
Newly collected data include the Longitudinal Study of Vaginal Flora, in which 3,620 nonpregnant women underwent quarterly study visits for 1 year. These visits included vaginal Gram stains, limited cultures, and detailed questioning regarding a variety of behavioral factors.
Investigating the Links between BV and Vitamin D
Researchers supported by the NICHD Pregnancy and Perinatology Branch (PPB) are exploring the idea that vitamin D deficiency is a significant risk factor for development of BV in healthy adult women. A link between vitamin D deficiency and increased risk of BV might help to explain racial disparities in the prevalence of BV. Identifying risk factors for BV that potentially could be modified may provide an opportunity to reduce its prevalence and associated morbidities. (Source: NIH RePORTER, 1K23HD065844-01A1)
Lactobacillus and Its Phages in BV
This joint U.S.-India study, also supported by PPB, investigated risk factors for BV among reproductive age women in Mysore, India, and sought to identify and to characterize Lactobacillus and Lactobacillus phages among this population. This study, the first of its kind ever to be conducted in India, will lay the foundation to test the hypothesis that bacteriophage might be responsible for causing BV. (Source: NIH RePORTER, 5R03HD055117-02)
Effects of Aspirin in Gestation and Reproduction (EAGeR) Study
The association between BV and anovulation, implantation failure, and pregnancy loss will be explored as part of the EAGeR Study, which is a multisite, randomized placebo-controlled clinical trial under the purview of the NICHD’s DIPHR. The study is designed to evaluate the effect of daily low-dose aspirin on live-birth rates and has numerous secondary objectives.
Oral & Vaginal Microbes, Human Genotype, and Preterm Birth
This project, which is supported by the NICHD PPB, aims to understand the role of microbes in the vaginal and oral cavities in triggering preterm birth and how this role may be modified by human genotype and known behavioral risk factors. Investigators will explore the joint effects of vaginal and oral microbes on preterm birth. (Source: NIH RePORTER, 5R01HD038098-07)
Investigating How Genital Mucus Secretions Trap Pathogens
Researchers supported by the Contraception Research Branch (CRB) also seek to clarify how mucus secretions from women with healthy vaginal flora help protect against pathogens and how abnormal mucus secretions caused by BV increase susceptibility to a broad range of viral, bacterial, and protozoal pathogens. Among the study goals, the protective roles of lactic acid and lactate anions will be investigated. The results may support the development of vaginal products and microbicides that reinforce the protective effects of lactic acid. (Source: NIH RePORTER, 5R01HD062844-03)
Vaginal Ring for Preventing Bacterial Vaginosis
Other researchers supported by NICHD CRB are developing a prototype vaginal ring that releases lactic acid to prevent BV ("BVP-Ring"). The project builds on research findings that lactic acid potentially inactivates a broad range of bacteria associated with BV. The ring will release lactic acid at a rate comparable to that produced by healthy Lactobacilli and thus will not make the vaginal environment too acidic. Researchers anticipate the ring to be useful for women with frequent episodes of symptomatic BV and for preventing BV during pregnancy. (Source: NIH RePORTER, 1R41HD066938-01)
Molecular Pathways of Inflammatory and Immune Responses to Trichomoniasis vaginalis
Researchers supported by NICHD CRB have made significant contributions to understanding immune evasion mechanisms exploited by T. vaginalis. Specifically, their research has focused on lipophosphoglycan, the main cell surface glycoconjugate of the parasite, and its role in triggering the vaginal mucosal inflammatory response. (Source: NIH RePORTER, 5R21HD054451-02; PMID: 18604640)
Other Activities and Advances
The PPB-supported Maternal-Fetal Medicine Units (MFMU) Network clinical trial, conducted in 1996–2000, screened approximately 30,000 women for BV and trichomoniasis. Those who were positive were randomized to treatment with metronidazole or placebo. This research contributed to the U.S. Preventive Services Task Force recommendation not to screen pregnant women for BV.