Understanding sexually transmitted infections, congenital infections, reproductive microbiology, maternal immunity, vaccination, and the importance of identifying preventable risks before conception.
When preparing for pregnancy, prospective parents often focus on reproductive hormones, nutrition, physical fitness, and metabolic health.
But another important dimension of reproductive health deserves attention: the relationship between infectious diseases, immune function, and human reproduction.
Could an infection that produces no noticeable symptoms affect someone's ability to conceive?
Can an infection acquired during pregnancy influence placental function or fetal development?
Why are some infections routinely screened for before or during pregnancy while others are not?
And how does the growing science of the reproductive microbiome change our understanding of maternal and infant health?
These questions are central to comprehensive preconception care.
In 2008, Coonrod and colleagues published The Clinical Content of Preconception Care: Infectious Diseases in Preconception Care in the American Journal of Obstetrics & Gynecology.
The authors examined a broad range of infections relevant to reproductive health, including HIV, hepatitis C, tuberculosis, toxoplasmosis, cytomegalovirus, chlamydia, gonorrhea, syphilis, herpes simplex virus, bacterial vaginosis, periodontal disease, and several other conditions.
Their objective was not to recommend testing every prospective parent for every possible infection.
Instead, they asked a more clinically meaningful question:
Which infections can be identified or addressed before conception in ways that meaningfully improve reproductive health or pregnancy outcomes?
Nearly two decades later, research published in JAMA, The New England Journal of Medicine, and Nature Portfolio journals has substantially expanded our understanding.
Advances in antiviral therapy, diagnostic testing, vaccination, and microbiome science have changed how clinicians approach several infections.
However, the central principle remains unchanged.
More testing is not always better healthcare.
Effective preconception care requires distinguishing infections that warrant early screening and treatment from conditions that are better addressed during pregnancy or only when specific clinical indications exist.
1. Why Infectious Disease Screening Matters Before Pregnancy
Infectious diseases can influence reproductive health through several different mechanisms.
Some infections directly affect reproductive tissues.
Others may cause systemic illness or complications during pregnancy.
Certain pathogens can cross the placenta or be transmitted during delivery, potentially affecting the developing fetus or newborn.
The consequences differ considerably depending on the organism involved.
For example, untreated chlamydia or gonorrhea can contribute to pelvic inflammatory disease and damage to reproductive structures.
Syphilis can cross the placenta and cause severe fetal complications.
HIV can be transmitted during pregnancy, childbirth, or breastfeeding, although effective treatment can dramatically reduce transmission risk.
Other infections, such as group B streptococcal colonization, are usually managed through screening and preventive treatment later in pregnancy rather than before conception.
Therefore, infectious disease screening should be guided by several considerations.
Can the infection affect fertility or reproductive health?
Is the infection likely to be asymptomatic?
Is an accurate screening test available?
Does detecting and treating the infection before conception improve a meaningful clinical outcome?
And is there a better time to perform the test?
These questions provide a more useful framework than indiscriminate infectious disease panels.
2. The Reproductive Immune System: Protection and Biological Regulation
The reproductive system must perform several functions that create unique immunological demands.
It must defend against potentially harmful microorganisms.
It must also support reproductive processes such as ovulation, fertilization, implantation, placentation, and pregnancy.
Immune cells and inflammatory mediators participate in many of these processes.
For example, localized inflammatory signaling contributes to normal ovulation.
Immune cells within the endometrium participate in tissue remodeling and the regulation of the uterine environment.
During pregnancy, maternal immune responses interact with placental tissues and fetal development.
However, the immune system does not simply become suppressed during pregnancy.
Instead, immune activity is regulated in ways that vary across tissues and stages of gestation.
Some immune pathways are essential for protecting against infection.
Others participate in supporting pregnancy.
This complexity explains why generalized claims about boosting immunity or suppressing inflammation are usually inappropriate.
An effective immune response depends on the specific biological challenge and tissue involved.
Excessive inflammation may be harmful in some circumstances.
Insufficient immune defense may also be harmful.
The objective is not maximal immune activity.
It is appropriately regulated immune function.
3. Chlamydia: Why an Infection Without Symptoms Can Affect Fertility
Chlamydia is caused by the bacterium Chlamydia trachomatis.
It is one of the most common bacterial sexually transmitted infections.
Many affected individuals experience no noticeable symptoms.
When symptoms occur, they may include abnormal vaginal discharge, urinary discomfort, pelvic pain, or bleeding between menstrual periods.
However, the absence of symptoms does not rule out infection.
Untreated chlamydia can spread to the upper reproductive tract and contribute to pelvic inflammatory disease.
Pelvic inflammatory disease may cause inflammation and damage involving the uterus, fallopian tubes, and surrounding tissues.
In some cases, resulting tubal damage can increase the risk of infertility or ectopic pregnancy.
Ectopic pregnancy occurs when implantation takes place outside the normal uterine cavity, most commonly within a fallopian tube.
This can be a medical emergency.
Because infection may be asymptomatic, screening is an important preventive strategy.
4. What Does JAMA Recommend for Chlamydia Screening?
In 2021, the U.S. Preventive Services Task Force published updated recommendations in JAMA concerning screening for chlamydia and gonorrhea.
The Task Force recommends screening sexually active women aged 24 years or younger and women aged 25 years or older who are at increased risk.
This recommendation applies to both pregnant and nonpregnant women.
Risk factors may include a new sexual partner, multiple sexual partners, a partner with a sexually transmitted infection, or other relevant circumstances.
Screening generally involves nucleic acid amplification testing, commonly abbreviated NAAT.
These tests detect genetic material from the organism.
Appropriate specimen options may include vaginal swabs or urine, depending on the clinical situation.
Treatment with recommended antibiotics can eliminate the infection.
However, treatment does not necessarily reverse reproductive damage that has already occurred.
This is one reason timely detection matters.
When an infection is identified, partner evaluation and treatment are also important for reducing reinfection.
The evidence supports targeted screening and treatment, not routine testing of everyone regardless of clinical circumstances.
5. Gonorrhea: Reproductive Health and Antibiotic Resistance
Gonorrhea is caused by Neisseria gonorrhoeae.
Like chlamydia, it can be present without obvious symptoms.
Untreated infection may contribute to cervicitis, pelvic inflammatory disease, tubal damage, and infertility.
Gonorrhea can also cause complications during pregnancy and may be transmitted to the newborn during delivery.
One important development since the 2008 AJOG publication is the continued evolution of antimicrobial resistance.
Neisseria gonorrhoeae has developed resistance to several antibiotics previously used for treatment.
Consequently, recommended treatment regimens have changed over time.
This makes appropriate diagnosis and guideline-directed treatment particularly important.
Patients should not attempt to treat suspected gonorrhea using leftover antibiotics or unverified antimicrobial supplements.
Clinical management should follow current recommendations and include partner management when indicated.
For individuals planning pregnancy, identifying and treating gonorrhea before conception can prevent ongoing infection and reduce the risk of certain complications.
6. Syphilis: A Preventable Cause of Serious Pregnancy Complications
Syphilis is caused by the bacterium Treponema pallidum.
The infection can progress through several stages and may remain asymptomatic for extended periods.
During pregnancy, untreated syphilis can cross the placenta and infect the fetus.
Congenital syphilis can cause miscarriage, stillbirth, premature birth, neonatal death, and serious developmental or organ-related complications.
This is particularly important because effective treatment is available.
Penicillin remains the established treatment for syphilis during pregnancy.
Timely diagnosis and treatment can prevent many cases of congenital infection.
However, syphilis remains a significant public health concern in the United States.
The 2008 AJOG paper described a period during which congenital syphilis rates had previously declined.
That situation has changed.
7. The Resurgence of Congenital Syphilis
In May 2025, the USPSTF reaffirmed its recommendation for universal syphilis screening during pregnancy in JAMA.
The recommendation carries an A grade, indicating high certainty of substantial net benefit.
The Task Force reported that the United States recorded 3,882 cases of congenital syphilis in 2023.
This included 279 congenital syphilis-related stillbirths and neonatal or infant deaths.
The number represented the highest reported burden in more than three decades.
The CDC has estimated that approximately 9 in 10 congenital syphilis cases may be preventable through timely testing and appropriate treatment.
These findings demonstrate why evidence-based screening is so important.
ACOG recommends syphilis screening at the first prenatal visit, again during the third trimester, and at birth.
A preconception visit provides an additional opportunity to identify infection before pregnancy.
However, a negative test before conception does not replace screening during pregnancy.
New infections can occur.
Preventive care therefore requires appropriate testing at the recommended times.
8. HIV: A Major Example of Scientific Progress in Reproductive Medicine
Few areas of reproductive infectious disease management have changed as dramatically as HIV.
HIV attacks components of the immune system and can lead to progressive immunodeficiency when untreated.
Historically, HIV infection presented substantial concerns for prospective parents because of the risk of transmission during pregnancy, delivery, and breastfeeding.
However, modern antiretroviral therapy has transformed prognosis and reproductive planning.
When individuals with HIV receive effective treatment and maintain viral suppression, the risk of perinatal transmission can become extremely low.
For a person living with HIV who wishes to become pregnant, preconception care can include reviewing antiretroviral therapy, viral load, general health, and the treatment plan for pregnancy.
Importantly, HIV infection does not automatically mean that someone should avoid pregnancy.
With appropriate medical care, many people living with HIV can conceive and have children who do not acquire the infection.
9. HIV Treatment, Viral Suppression, and Reproductive Planning
A central objective of HIV treatment is maintaining viral suppression.
This means reducing the amount of circulating HIV to levels that are very low or below the detection limit of standard laboratory tests.
For sexual transmission, sustained viral suppression supports the well-established principle known as Undetectable = Untransmittable, or U=U.
However, guidance concerning pregnancy and infant feeding requires separate consideration because the routes and consequences of transmission differ.
Current U.S. perinatal HIV guidance emphasizes effective antiretroviral treatment, regular viral-load monitoring, and individualized obstetric management.
Treatment should be established before conception when possible.
Medication regimens may require review to ensure they are appropriate for pregnancy.
Infant-feeding counseling has also evolved since 2008.
Current U.S. guidance supports patient-centered shared decision-making concerning feeding options for individuals with HIV who maintain viral suppression.
Formula feeding or pasteurized donor human milk eliminates the risk of postnatal HIV transmission through breastfeeding.
Breastfeeding with sustained maternal viral suppression carries a very low risk, but not zero risk, and requires appropriate specialist guidance.
These developments illustrate how scientific progress can expand reproductive options while maintaining careful risk assessment.
10. Hepatitis C: Why the Original 2008 Recommendations Have Changed
Hepatitis C is a viral infection that primarily affects the liver.
Many individuals experience no symptoms during the early stages.
Untreated chronic infection can lead to liver inflammation, fibrosis, cirrhosis, and other complications over time.
Hepatitis C can also be transmitted from a pregnant individual to the infant.
In 2008, the AJOG article described hepatitis C treatment using interferon-based regimens and recommended screening primarily according to risk factors.
This is one of the most important areas requiring modernization.
Highly effective direct-acting antiviral medications have since transformed hepatitis C treatment.
Many treatment regimens can cure the infection in more than 95% of appropriately selected patients.
Consequently, identifying hepatitis C before conception creates an opportunity to consider curative treatment before pregnancy.
11. Universal Hepatitis C Screening and Treatment Before Pregnancy
Current CDC guidance recommends hepatitis C screening for all adults at least once and during each pregnancy.
A positive hepatitis C antibody test is followed by an RNA test to determine whether active infection is present.
This distinction matters because antibodies may remain detectable after a previous infection has cleared or been successfully treated.
For individuals planning pregnancy, identification of active hepatitis C can lead to specialist evaluation.
When feasible, treatment before conception can eliminate active maternal infection and therefore remove the associated risk of transmission from that infection during a future pregnancy.
However, hepatitis C treatment during pregnancy remains an evolving area.
Direct-acting antiviral therapy has not yet become a universally recommended routine treatment during pregnancy.
Clinical decisions depend on available safety evidence and specialist assessment.
Patients receiving treatment should discuss pregnancy planning with the prescribing clinician rather than assuming that every medication is appropriate during gestation.
12. Hepatitis B: An Essential Addition to Modern Preconception Care
Although the 2008 article emphasized hepatitis C, hepatitis B deserves significant attention in contemporary reproductive healthcare.
Hepatitis B can cause acute or chronic liver infection.
Chronic infection may remain asymptomatic for years.
The virus can be transmitted from a mother to her infant during childbirth.
However, effective prevention strategies are available.
These include maternal screening, appropriate antiviral treatment in selected pregnancies, and neonatal immunization.
Current CDC recommendations include screening all adults for hepatitis B at least once using a three-part laboratory panel.
This panel includes hepatitis B surface antigen, surface antibody, and core antibody.
The results help distinguish active infection, immunity from vaccination, and previous natural infection.
Pregnant individuals should also undergo hepatitis B surface antigen screening during each pregnancy.
For an individual known to have chronic hepatitis B, pregnancy planning may include specialist evaluation, viral-load assessment, and treatment decisions.
Neonatal preventive measures are especially important when maternal hepatitis B infection is present.
13. Tuberculosis: When Preconception Screening Is Appropriate
Tuberculosis is caused by Mycobacterium tuberculosis.
Infection can be latent or active.
Latent tuberculosis infection means the organism is present without symptoms or evidence of active disease.
However, latent infection can progress to active tuberculosis in some circumstances.
Active tuberculosis during pregnancy can create significant health risks for the mother and infant.
Screening before pregnancy may be appropriate for individuals with relevant exposure histories or other risk factors.
These can include close contact with someone who has infectious tuberculosis, residence in or travel from regions with higher prevalence, or certain medical conditions affecting immune function.
Testing may involve an interferon-gamma release assay or a tuberculin skin test.
A positive screening result requires evaluation to distinguish latent infection from active disease.
Treatment decisions should be individualized.
Not everyone needs routine tuberculosis screening solely because pregnancy is being planned.
The appropriate strategy depends on risk.
14. Cytomegalovirus: One of the Most Important Congenital Infections
Cytomegalovirus, commonly abbreviated CMV, is a member of the herpesvirus family.
Many infections are asymptomatic or produce mild symptoms.
However, infection during pregnancy can sometimes result in transmission to the developing fetus.
Congenital CMV is an important cause of sensorineural hearing loss and can be associated with additional neurological and developmental complications.
Risk depends partly on the circumstances of maternal infection.
Primary infection during pregnancy can present a greater risk of fetal transmission or certain complications than some nonprimary infections.
However, congenital CMV can occur after either primary or nonprimary maternal infection.
The original AJOG paper emphasized prevention through appropriate hygiene.
This remains relevant.
But more recent studies have investigated whether interventions can prevent congenital transmission after maternal infection.
15. What NEJM Research Reveals About CMV Treatment
In 2021, researchers published A Trial of Hyperimmune Globulin to Prevent Congenital Cytomegalovirus Infection in The New England Journal of Medicine.
The randomized, placebo-controlled study evaluated pregnant women with primary CMV infection diagnosed before 24 weeks of gestation.
Participants received either CMV hyperimmune globulin or placebo.
The trial was stopped early for futility.
The primary outcome occurred in approximately 22.7% of the hyperimmune globulin group and 19.4% of the placebo group.
The investigators did not demonstrate a reduction in congenital CMV infection.
This finding is important because plausible biological interventions do not always produce clinical benefits.
Researchers have also investigated high-dose valacyclovir in selected maternal CMV infections.
Some studies have reported promising results.
However, ACOG does not currently recommend routine use of valacyclovir for congenital CMV prevention outside research protocols because evidence and safety considerations remain insufficient for routine application.
Similarly, universal maternal CMV serologic screening is not currently recommended in routine U.S. prenatal care.
For suspected maternal CMV infection, specialist evaluation is important.
16. Reducing CMV Exposure: Practical Prevention Without Excessive Anxiety
CMV can spread through bodily fluids, including saliva and urine.
Young children may shed CMV without obvious illness.
Consequently, individuals who regularly care for infants or toddlers may encounter relevant exposures.
Reasonable prevention practices include washing hands after changing diapers or handling bodily fluids.
Avoiding unnecessary sharing of eating utensils, drinks, or toothbrushes with young children can also reduce exposure opportunities.
These recommendations do not mean that parents should avoid ordinary physical affection with their children.
The objective is practical hygiene, not social isolation.
The effectiveness of individual behavioral strategies in preventing congenital CMV has not been established with the same certainty as vaccination for vaccine-preventable infections.
Nevertheless, appropriate hygiene remains a reasonable preventive measure.
17. Toxoplasmosis: Food Safety, Soil, and Animal Exposure
Toxoplasmosis is caused by the parasite Toxoplasma gondii.
Infection can occur through ingestion of contaminated food or water, undercooked meat, or contact with infectious material in soil or cat feces.
Primary maternal infection during pregnancy can sometimes result in congenital toxoplasmosis.
Potential complications include neurological or visual abnormalities.
However, the risk of transmission and severity of disease vary according to gestational timing.
The original AJOG paper recommended education concerning food preparation, soil exposure, and cat litter.
These principles remain useful.
Practical measures include cooking meat appropriately, washing produce, cleaning food-preparation surfaces, and using gloves during gardening.
Individuals who handle cat litter should use appropriate hygiene precautions.
However, owning a cat does not automatically create an unacceptable pregnancy risk.
Routine universal toxoplasmosis screening before pregnancy is not recommended in the United States.
Testing is generally based on specific clinical circumstances.
18. Listeria: Why Food Safety Matters During Pregnancy
Listeriosis is caused by Listeria monocytogenes.
This bacterium can contaminate food and is particularly concerning during pregnancy because infection can contribute to miscarriage, stillbirth, preterm birth, or neonatal infection.
One unusual characteristic of Listeria is its ability to grow at refrigerator temperatures.
Consequently, refrigeration alone does not eliminate risk.
Current food-safety recommendations emphasize avoiding unpasteurized dairy products and appropriately handling ready-to-eat foods that may carry increased risk.
Certain deli meats and similar products may require reheating until steaming hot.
Food safety should also include appropriate storage temperatures, avoidance of cross-contamination, and attention to recalls.
However, not every refrigerated food carries the same risk.
The goal is informed food selection and preparation rather than eliminating large categories of nutritious foods without reason.
19. Parvovirus B19: Why Exposure During Pregnancy Can Matter
Parvovirus B19 causes fifth disease, an infection often associated with a characteristic facial rash in children.
Many adults have already developed immunity from previous exposure.
However, infection during pregnancy can occasionally affect fetal red blood cell production.
In severe cases, this can lead to fetal anemia and hydrops fetalis.
The original AJOG paper discussed these risks and noted that universal preconception immunity screening had not demonstrated clinical benefit.
That distinction remains important.
Routine testing of all prospective parents for parvovirus B19 is not generally indicated.
However, known exposure during pregnancy may justify clinical evaluation.
Management depends on the timing of exposure, laboratory findings, and fetal assessment.
Specialist care may be needed in selected cases.
20. Malaria and Travel-Related Infections
Travel can introduce infectious risks that differ considerably according to destination.
Malaria is one important example.
Infection during pregnancy can increase the risk of severe maternal illness, anemia, fetal growth restriction, and other complications.
Individuals planning pregnancy who expect to travel to areas where malaria occurs should discuss their itinerary with a qualified travel-medicine professional.
Preventive recommendations may include mosquito avoidance strategies and appropriate chemoprophylaxis.
Medication selection depends on the destination, local resistance patterns, pregnancy status, and other clinical factors.
Other travel-related infections may also be relevant, including Zika virus in regions with current or past transmission concerns.
Recommendations concerning conception timing after possible Zika exposure depend on current public health guidance and the exposure circumstances.
Because travel-related infectious risks change over time, individualized assessment using current recommendations is essential.
21. Herpes Simplex Virus: Understanding Transmission Risk
Herpes simplex virus type 1 and type 2 can cause oral or genital infections.
Once acquired, the virus establishes lifelong latency.
Antiviral medications can reduce symptoms and viral shedding but do not eliminate latent infection.
The primary obstetric concern is neonatal herpes, which can be severe.
Transmission risk is particularly important when maternal genital herpes is newly acquired near the time of delivery.
For individuals with known genital herpes, preconception counseling can address transmission prevention and pregnancy management.
During pregnancy, suppressive antiviral therapy may be recommended beginning around 36 weeks for selected patients.
Cesarean delivery may be indicated when active genital lesions or prodromal symptoms are present during labor.
However, routine HSV antibody screening of all asymptomatic prospective parents is not recommended.
Testing should be guided by clinical history and circumstances.
22. The Vaginal Microbiome: A New Frontier in Reproductive Medicine
One of the most significant scientific developments since 2008 is the ability to examine microbial communities using molecular sequencing technologies.
The vaginal microbiome contains microorganisms that interact with local tissues, mucosal barriers, and immune signaling.
In many reproductive-age women, Lactobacillus species are prominent members of the vaginal microbial community.
These bacteria can contribute to vaginal acidity through the production of lactic acid.
An acidic environment can help limit the growth of some potentially harmful microorganisms.
However, vaginal microbial communities vary among individuals and across time.
Not every variation represents disease.
Similarly, the presence of a particular bacterial species does not automatically imply an infection requiring treatment.
Researchers are increasingly interested in whether microbial patterns are associated with fertility, implantation, pregnancy complications, or preterm birth.
23. Bacterial Vaginosis: More Than a Simple Infection
Bacterial vaginosis, or BV, is a condition involving changes in vaginal microbial communities.
It commonly involves reduced dominance of certain Lactobacillus species and increased abundance of diverse anaerobic bacteria.
Symptoms may include abnormal vaginal discharge or odor.
However, some individuals have no symptoms.
BV has been associated with pelvic inflammatory disease, acquisition of certain sexually transmitted infections, and adverse pregnancy outcomes.
The original AJOG paper highlighted associations between bacterial vaginosis and preterm birth.
However, the authors also recognized that observational associations did not establish that routine screening and treatment would improve outcomes.
This distinction remains crucial.
A microbial pattern may be statistically associated with increased risk while treatment directed at that pattern fails to prevent the outcome.
This is one reason the microbiome deserves careful scientific interpretation.
24. What Does Modern Microbiome Research Show About Preterm Birth?
A 2025 study published in npj Biofilms and Microbiomes, Vaginal Host Immune-Microbiome-Metabolite Interactions Associated With Spontaneous Preterm Birth, investigated microbial, inflammatory, and metabolic characteristics during pregnancy.
Researchers analyzed vaginal samples collected at two gestational periods from women who subsequently delivered either preterm or at term.
They identified differences involving microbial composition, metabolites, and inflammatory signaling.
For example, certain samples from pregnancies ending in preterm delivery showed greater abundance of Gardnerella vaginalis and differences in selected metabolites.
The findings support the hypothesis that vaginal microbial communities interact with local immune and metabolic processes relevant to pregnancy.
However, this was a relatively small observational study.
The findings do not establish that the bacteria caused preterm delivery.
Nor do they demonstrate that treating the identified microbial patterns would prevent prematurity.
In addition, microbial patterns may vary across populations, and findings from one cohort may not generalize to all women.
The research is scientifically promising, but its routine clinical application remains uncertain.
25. Should Everyone Get a Vaginal Microbiome Test Before Pregnancy?
Despite growing interest in vaginal microbiome sequencing, routine comprehensive microbiome testing is not an established requirement of preconception care.
Commercial panels may identify numerous bacterial species and report relative abundances.
However, clinical usefulness depends on whether those measurements reliably predict meaningful outcomes and support effective interventions.
For example, a report showing reduced relative abundance of a particular Lactobacillus species does not automatically establish that a patient requires antibiotics or probiotics.
Likewise, broad efforts to eliminate bacteria described as unfavorable may disrupt normal microbial communities.
For symptomatic bacterial vaginosis, established diagnostic methods and appropriate treatment remain important.
However, the USPSTF recommends against screening asymptomatic pregnant individuals who are not at increased risk of preterm birth solely to prevent preterm delivery.
For asymptomatic individuals at increased risk, available evidence remains insufficient to determine whether screening provides a net benefit.
These recommendations concern pregnancy, but they also illustrate why routine microbiome screening before conception should not be adopted without evidence.
26. What About Vaginal Probiotics and Microbiome Restoration?
Probiotics are live microorganisms administered with the intention of providing a health benefit.
Some products contain Lactobacillus species associated with vaginal microbial communities.
Researchers are investigating whether selected probiotics or microbiome-directed interventions can reduce bacterial vaginosis recurrence or improve reproductive outcomes.
However, effects are often strain-specific and depend on the condition being treated.
A supplement containing one Lactobacillus species should not be assumed equivalent to another product.
Furthermore, changing microbial composition does not automatically demonstrate improved fertility, implantation, or reduced preterm birth.
At present, routine probiotic treatment for all prospective parents as a strategy to prevent pregnancy complications is not supported by sufficiently strong evidence.
Patients with recurrent symptoms may benefit from appropriate gynecologic evaluation rather than self-directed antimicrobial or probiotic protocols.
27. Periodontal Disease: Can Oral Health Influence Pregnancy?
Periodontal disease involves inflammation and destruction of tissues supporting the teeth.
It can include changes in oral microbial communities and host inflammatory responses.
Observational studies have associated periodontal disease with certain adverse pregnancy outcomes, including preterm birth.
The original AJOG paper discussed the possibility that inflammatory signaling originating in the oral cavity might influence maternal or fetal physiology.
However, it also recognized that treatment studies had produced inconsistent results.
Subsequent research has continued to distinguish two separate questions.
Does periodontal treatment improve oral health?
And does periodontal treatment prevent obstetric complications?
The first question has a clearer answer.
Appropriate periodontal treatment can improve oral health and manage gum disease.
The second remains less certain.
Evidence has not established that routine periodontal treatment prevents preterm birth.
Nevertheless, maintaining oral health is beneficial in its own right.
A preconception dental evaluation may therefore be appropriate, particularly for individuals with untreated dental disease.
28. Group B Streptococcus: Why Timing of Screening Matters
Group B streptococcus, or GBS, can colonize the gastrointestinal and genital tracts without causing symptoms.
During childbirth, the organism may be transmitted to the infant.
In some cases, neonatal infection can cause sepsis, pneumonia, or meningitis.
Preventive strategies have significantly reduced early-onset GBS disease.
However, GBS colonization can change over time.
This is why screening before pregnancy is generally not useful for predicting colonization at delivery.
Current obstetric guidance recommends universal vaginal–rectal screening at approximately 36–37 weeks of gestation in most pregnancies.
When indicated, antibiotics administered during labor can reduce the risk of neonatal transmission.
The appropriate management differs for individuals with GBS bacteriuria during pregnancy or a previous infant affected by invasive GBS disease.
The key principle is that some infections are best addressed at a particular stage of pregnancy.
Preconception testing is not necessarily beneficial simply because an organism can influence newborn health.
29. Asymptomatic Bacteriuria: Another Example of Appropriate Timing
Asymptomatic bacteriuria occurs when bacteria are present in the urine without the typical symptoms of a urinary tract infection.
During pregnancy, untreated bacteriuria can increase the risk of kidney infection.
Screening and appropriate treatment during pregnancy can reduce the risk of pyelonephritis.
However, routine screening and treatment of asymptomatic bacteriuria before pregnancy in otherwise healthy nonpregnant adults are not generally recommended.
The benefit depends on the clinical population.
This distinction is important because unnecessary antibiotic treatment can cause adverse effects and contribute to antimicrobial resistance.
The objective is to treat clinically meaningful infections when evidence demonstrates benefit.
It is not to eliminate every detectable microorganism.
30. Vaccination: One of the Strongest Tools in Preconception Infectious Disease Prevention
Vaccination is an essential component of infectious disease prevention.
Unlike some investigational microbiome interventions, vaccines have substantial evidence supporting prevention of particular infections and complications.
Preconception care provides an opportunity to review immunization records and identify needed vaccines.
For example, rubella infection during early pregnancy can cause congenital rubella syndrome.
Individuals without evidence of immunity may benefit from vaccination before conception.
The measles–mumps–rubella vaccine is a live attenuated vaccine and is not administered during pregnancy.
Varicella vaccination is another important preconception consideration for susceptible individuals.
Because the vaccine is live attenuated, it is also contraindicated during pregnancy.
Pregnancy should generally be avoided for one month after either MMR or varicella vaccination.
Other vaccines, such as hepatitis B vaccination, can be administered during pregnancy when indicated.
Vaccination planning should therefore distinguish vaccines that need to be completed before pregnancy from those recommended during pregnancy.
31. Maternal Vaccination and Protection of the Newborn
A major development in reproductive immunology is the use of maternal vaccination to protect infants after birth.
Antibodies generated following vaccination can cross the placenta, providing a degree of passive protection to the newborn.
A 2023 randomized trial published in The New England Journal of Medicine, Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, evaluated vaccination against respiratory syncytial virus.
The investigators enrolled more than 7,000 pregnant participants.
Maternal vaccination reduced medically attended severe RSV-associated lower respiratory tract illness among infants.
Vaccine efficacy against this outcome was approximately 81.8% within the first 90 days after birth and 69.4% within the first 180 days.
These results supported the development of maternal RSV immunization strategies.
Current U.S. recommendations involve administering the appropriate maternal RSV vaccine during a defined gestational window and season, with infant monoclonal antibody protection serving as an alternative in many circumstances.
This is an important example of maternal immune protection extending beyond pregnancy.
However, vaccine selection and timing should follow current recommendations and individual clinical circumstances.
32. Why Preconception Care Should Include Both Partners
Infectious disease prevention is not exclusively a maternal responsibility.
Both prospective parents can influence reproductive infection risk.
For example, untreated sexually transmitted infections can be transmitted between partners.
Reinfection may occur when one individual is treated but their partner remains infected.
Preconception care should therefore consider sexual health, relevant screening, and appropriate treatment for both individuals.
Partners may also contribute to infection prevention through vaccination and other preventive measures.
However, testing should remain clinically appropriate.
A positive infection test does not automatically establish when or from whom an infection was acquired.
Some infections can remain asymptomatic for prolonged periods.
Sensitive communication, confidentiality, and respect for patient autonomy are essential.
33. Why More Infectious Disease Testing Is Not Always Better
The increasing availability of laboratory technology has made it possible to detect numerous microbial organisms, antibodies, and genetic fragments.
However, detection does not always indicate active infection.
For example, a positive IgG antibody result may reflect previous exposure rather than current disease.
A positive molecular test may require interpretation according to specimen type, clinical context, and assay characteristics.
Some organisms colonize healthy tissues without producing disease.
Others may be present transiently.
Broad testing can therefore identify findings that have little clinical significance.
These results may create confusion, unnecessary treatment, and additional costs.
A particularly important distinction exists between detecting a pathogen and demonstrating that treatment improves health outcomes.
For preconception care, screening should be selected according to validated recommendations, relevant risk factors, symptoms, and medical history.
Indiscriminate viral panels, broad immune testing, or comprehensive microbiome sequencing should not be presented as routine requirements for pregnancy preparation.
34. Practical Steps for Prospective Parents
A comprehensive infectious disease review can include several practical considerations.
Review appropriate STI screening. Chlamydia, gonorrhea, HIV, and syphilis testing should be offered according to current recommendations and individual circumstances.
Check hepatitis screening history. Adults should receive appropriate hepatitis B and C screening, and pregnancy-specific testing remains necessary.
Review vaccination records. Confirm whether preconception MMR or varicella vaccination is needed and discuss vaccines recommended during pregnancy.
Address known infections. Obtain appropriate treatment and follow-up before conception when clinically indicated.
Include both partners. Partner testing and treatment may be necessary to prevent transmission or reinfection.
Practice appropriate food hygiene. Reduce preventable risks associated with toxoplasmosis, listeriosis, and other foodborne infections.
Review travel plans. Discuss relevant malaria or other destination-specific infection risks before attempting pregnancy.
Maintain dental and reproductive health. Seek evaluation for persistent symptoms rather than relying on generalized antimicrobial or microbiome protocols.
Avoid unnecessary testing. Choose diagnostic procedures according to clinical usefulness rather than the number of organisms a test can detect.
Establish appropriate prenatal care. Preconception evaluation does not replace screening required during pregnancy.
These actions support prevention without creating unrealistic expectations that every infectious exposure can be eliminated.
35. How This Research Informs Our Preconception Care
We recognize that reproductive health involves interactions among immune regulation, microbial communities, environmental exposures, and broader physiological systems.
Within our women's health and conscious conception philosophy, infection-related education is an important component of comprehensive preconception planning.
Our approach emphasizes understanding medical history, identifying relevant risk factors, reviewing preventive care, and facilitating appropriate referrals.
This may involve discussing vaccination history, sexual health screening, known chronic infections, and lifestyle behaviors relevant to reducing exposure.
We also recognize the growing scientific interest in the vaginal, gastrointestinal, and oral microbiomes.
However, microbiome research should be interpreted carefully.
The identification of microbial associations does not automatically justify extensive laboratory testing or antimicrobial treatment.
Similarly, a history of positive viral antibodies should not be assumed to indicate an active infection requiring intervention.
When an infectious disease requires diagnosis, prescription treatment, or specialist management, these services belong with appropriately qualified medical professionals.
Our role is to support informed health decisions, appropriate prevention, and collaboration with the broader healthcare team.
The objective is not to create a biologically sterile environment.
It is to help prospective parents identify meaningful risks and access evidence-based care.
Conclusion: Infection Prevention Is About Timing, Evidence, and Appropriate Care
Infectious diseases can influence fertility, pregnancy outcomes, and infant health through many different mechanisms.
Some infections damage reproductive tissues.
Others affect the placenta or can be transmitted to the developing fetus.
Certain conditions are highly treatable.
Others require specialized monitoring or prevention.
Since the original 2008 AJOG publication, advances in antiviral medications, screening technology, immunization, and reproductive microbiology have substantially expanded the available options.
HIV treatment has transformed reproductive planning.
Hepatitis C can now be cured in many patients before conception.
Syphilis screening remains essential because congenital infections are often preventable through timely diagnosis and treatment.
Maternal vaccination can provide meaningful protection to infants.
And microbiome research is revealing increasingly complex interactions among microorganisms, immune signaling, and reproductive tissues.
However, modern research also demonstrates the importance of clinical restraint.
A microbial association is not proof of causation.
A positive laboratory result is not always evidence of active infection.
And testing or treating an asymptomatic condition does not necessarily improve pregnancy outcomes.
The purpose of preconception infectious disease care is not to find every organism or eliminate every exposure. It is to identify infections that matter, intervene when evidence supports intervention, and provide the right preventive care at the right time.
For prospective parents, this means combining appropriate screening, vaccination, treatment, hygiene, and ongoing healthcare with a realistic understanding of what science can—and cannot—predict.
Research References
Coonrod DV, Jack BW, Stubblefield PG, et al. The clinical content of preconception care: infectious diseases in preconception care. American Journal of Obstetrics and Gynecology. 2008;199(6 Suppl 2)–S309. https://doi.org/10.1016/j.ajog.2008.08.062
US Preventive Services Task Force. Screening for chlamydia and gonorrhea: US Preventive Services Task Force recommendation statement. JAMA. 2021;326(10):949–956. https://doi.org/10.1001/jama.2021.14081
US Preventive Services Task Force. Screening for syphilis infection during pregnancy: reaffirmation recommendation statement. JAMA. 2025;333(22):2006–2012. https://doi.org/10.1001/jama.2025.5009
Asher GN, Viswanathan M, Takyi A, et al. Screening for syphilis infection during pregnancy: evidence report for the USPSTF. JAMA. 2025. https://doi.org/10.1001/jama.2025.1179
Hughes BL, Clifton RG, Rouse DJ, et al. A trial of hyperimmune globulin to prevent congenital cytomegalovirus infection. New England Journal of Medicine. 2021;385:436–444. https://doi.org/10.1056/NEJMoa1913569
Revello MG, Lazzarotto T, Guerra B, et al. A randomized trial of hyperimmune globulin to prevent congenital cytomegalovirus. New England Journal of Medicine. 2014;370:1316–1326. https://doi.org/10.1056/NEJMoa1310214
Kampmann B, Madhi SA, Munjal I, et al. Bivalent prefusion F vaccine in pregnancy to prevent RSV illness in infants. New England Journal of Medicine. 2023;388:1451–1464. https://doi.org/10.1056/NEJMoa2216480
Cavanagh M, Amabebe E, Kulkarni NS, et al. Vaginal host immune-microbiome-metabolite interactions associated with spontaneous preterm birth in a predominantly white cohort. npj Biofilms and Microbiomes. 2025;11:52. https://doi.org/10.1038/s41522-025-00671-4
Lee KY, Shin SH, Park G, et al. Shotgun metagenomics of the vaginal microbiome in cervical shortening and preterm birth risk. Scientific Reports. 2025;15:39988. https://doi.org/10.1038/s41598-025-23737-x
Centers for Disease Control and Prevention. Screening and testing for HIV, viral hepatitis, STDs, and tuberculosis in pregnancy. https://www.cdc.gov/pregnancy-hiv-std-tb-hepatitis/php/screening/index.html
Centers for Disease Control and Prevention. Clinical screening and diagnosis for hepatitis C. Updated November 2026. https://www.cdc.gov/hepatitis-c/hcp/diagnosis-testing/index.html
Centers for Disease Control and Prevention. Clinical overview of hepatitis B. https://www.cdc.gov/hepatitis-b/hcp/clinical-overview/index.html
American College of Obstetricians and Gynecologists. Screening for syphilis in pregnancy. 2024; reaffirmed 2025. https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2024/04/screening-for-syphilis-in-pregnancy
American College of Obstetricians and Gynecologists. Cytomegalovirus (CMV) in pregnancy. https://www.acog.org/clinical-information/physician-faqs/cytomegalovirus-in-pregnancy
US Preventive Services Task Force. Bacterial vaginosis in pregnant persons to prevent preterm delivery: screening. 2020. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/bacterial-vaginosis-in-pregnancy-to-prevent-preterm-delivery-screening
Centers for Disease Control and Prevention. Guidelines for vaccinating pregnant women. 2025. https://www.cdc.gov/vaccines-pregnancy/hcp/vaccination-guidelines/
American College of Obstetricians and Gynecologists. Maternal immunization schedule. 2026. https://www.acog.org/clinical-information/maternal-immunization-schedule
National Institutes of Health. Perinatal HIV clinical guidelines. https://clinicalinfo.hiv.gov/en/guidelines/perinatal
Centers for Disease Control and Prevention. Sexually transmitted infections treatment guidelines. https://www.cdc.gov/std/treatment-guidelines/