STI statistics for women: what the CDC data actually shows

In my clinic, I see a version of this scenario several times a month. A woman comes in for an unrelated issue (irregular bleeding, a routine Pap, pelvic pain) and a chlamydia test comes back positive. She had no symptoms. Neither did her partner. The infection may have been there for months, quietly doing damage to her reproductive tract that she will not discover until she tries to get pregnant.

Sexually transmitted infections are among the most common infectious diseases in the United States, and women face a biological asymmetry that makes STIs more consequential for them. The infections are often silent in women, harder to detect on physical exam, and more likely to cause long-term damage to the reproductive organs. The latest CDC surveillance data, covering 2023, shows a complicated picture: chlamydia and gonorrhea remain at high levels, syphilis is surging, and the public health infrastructure meant to control these infections is stretched thin.

The current STI picture in the United States

The CDC's 2023 STI Surveillance Report documented more than 2.7 million reported cases of chlamydia, gonorrhea, and syphilis combined. That figure almost certainly undercounts the true burden because millions of infections go undiagnosed and unreported.

Reported STI cases in the U.S., 2023. Source: CDC STI Surveillance Report.

The trend lines differ by infection. Chlamydia case counts have been roughly stable at around 1.8 million per year since 2019, though this likely reflects testing capacity more than actual prevalence. Gonorrhea cases have risen about 45% since 2015. Syphilis has seen the most alarming trajectory: total cases more than tripled between 2015 and 2023, and congenital syphilis (transmitted from mother to infant during pregnancy) has increased more than 900% over the past decade.

The WHO estimates that globally, more than 1 million STIs are acquired every day. In the United States, the CDC estimates that roughly 1 in 5 people have an STI at any given time, accounting for about 68 million prevalent infections.

These are not just numbers on a surveillance report. They represent infections that, in women, carry disproportionate consequences — from infertility to cervical cancer to congenital transmission. And the public health programs designed to prevent, test for, and treat STIs have faced consistent funding shortfalls. The CDC's Division of STD Prevention budget, adjusted for inflation, has declined by roughly 40% since 2003, according to KFF analysis.

Chlamydia: the most common and most silent

Chlamydia is the most frequently reported bacterial STI in the United States, with approximately 1.8 million cases reported to the CDC annually. The actual number of infections is estimated at closer to 4 million when unreported and undiagnosed cases are included.

The central problem with chlamydia in women is that it is overwhelmingly asymptomatic. The CDC estimates that up to 80% of chlamydia infections in women produce no symptoms. A woman can carry the infection for months or years without knowing it. During that time, the bacteria can ascend from the cervix into the uterus and fallopian tubes, causing inflammation that leads to scarring.

When symptoms do appear, they tend to be mild: abnormal vaginal discharge, burning with urination, bleeding between periods. These overlap with a dozen other conditions, including yeast infections and urinary tract infections. The result is that many women either dismiss the symptoms or receive an incorrect initial diagnosis.

Chlamydia rates are highest among women aged 15 to 24. The CDC reported a rate of 3,649 cases per 100,000 women in the 20-to-24 age group in 2023, roughly five times the overall population rate. This concentration in younger women drives the screening recommendation: annual chlamydia testing for all sexually active women under 25.

Left untreated, chlamydia progresses to pelvic inflammatory disease in about 10% to 15% of cases. PID, in turn, causes tubal damage that leads to infertility in roughly 12% of cases after a single episode and 40% after three or more episodes. Ectopic pregnancy (a potentially life-threatening complication) is six to ten times more common in women with a history of PID.

Gonorrhea: rising rates, growing resistance

Gonorrhea case counts have risen substantially over the past decade. The CDC reported approximately 650,000 cases in 2023, with rates increasing among both men and women. Women accounted for roughly 36% of reported cases, though female gonorrhea is underdetected because, like chlamydia, it is frequently asymptomatic in women.

An estimated 50% to 80% of gonorrhea infections in women produce no symptoms or symptoms mild enough to ignore. When symptomatic, gonorrhea may cause increased vaginal discharge, painful urination, or bleeding between periods — a presentation nearly identical to chlamydia. This is why dual testing for chlamydia and gonorrhea is standard practice.

The growing concern with gonorrhea is antibiotic resistance. Neisseria gonorrhoeae, the bacterium that causes gonorrhea, has developed resistance to every class of antibiotic ever used against it. The current CDC-recommended first-line treatment is a single 500 mg intramuscular dose of ceftriaxone. Resistance to ceftriaxone is still rare in the U.S., but surveillance data from the CDC's Gonococcal Isolate Surveillance Project has identified isolates with elevated minimum inhibitory concentrations, which is an early warning sign.

If ceftriaxone resistance becomes widespread, the clinical options narrow quickly. The WHO has classified antimicrobial-resistant gonorrhea as a high-priority pathogen. Several candidate drugs are in development, but none has yet reached the market.

Untreated gonorrhea, like chlamydia, can cause PID, tubal infertility, and ectopic pregnancy. It can also disseminate through the bloodstream, causing septic arthritis and, rarely, endocarditis. During pregnancy, gonorrhea transmission to the newborn can cause gonococcal ophthalmia, a serious eye infection that can lead to blindness if not treated at birth.

Syphilis and the congenital crisis

Syphilis is the STI story that public health officials are most worried about right now.

Primary and secondary syphilis (the stages when the infection is most transmissible) increased by more than 80% among women between 2018 and 2023, according to CDC data. The rate of increase among women has outpaced that among men in recent years, reversing a long-standing pattern. In 2023, the CDC reported approximately 207,000 total syphilis cases across all stages, including over 3,800 cases of congenital syphilis.

Congenital syphilis occurs when a pregnant woman transmits the infection to her baby during pregnancy or delivery. The consequences are severe: stillbirth, neonatal death, bone deformities, neurological damage, and developmental delays. In 2023, congenital syphilis caused 279 stillbirths and infant deaths. That number was 22 in 2012. The tenfold increase represents one of the most dramatic infectious disease failures in modern American public health.

The tragedy is that congenital syphilis is almost entirely preventable. A single penicillin injection given at least 30 days before delivery treats maternal syphilis and prevents transmission to the infant. The barrier is not treatment — it is screening. The CDC recommends syphilis testing at the first prenatal visit, and many states now mandate repeat testing in the third trimester. But women who receive no prenatal care, or whose prenatal care is delayed, fall through the gap.

In the states with the highest congenital syphilis rates (Texas, Louisiana, Arizona, California) the common thread is inadequate access to early prenatal care, often in the same communities affected by maternity care deserts. Our article on healthcare access disparities covers this overlap in detail.

HPV: the most prevalent STI

Human papillomavirus is in a category of its own. It is the most common STI in the world. Approximately 80% of sexually active people will acquire at least one type of HPV in their lifetime. At any given time, an estimated 42 million Americans have HPV infections, with about 13 million new infections per year.

Most HPV infections are cleared by the immune system within one to two years and cause no symptoms or health problems. The concern is the subset that persists. Persistent infection with high-risk HPV types (primarily types 16 and 18) is the cause of nearly all cervical cancers, as well as a significant proportion of vaginal, vulvar, anal, and oropharyngeal cancers.

The National Cancer Institute reports that HPV causes approximately 37,000 cancers per year in the United States. Cervical cancer accounts for about 13,000 of those cases annually, with roughly 4,000 deaths. Almost all cervical cancer cases (more than 99%) are linked to persistent high-risk HPV infection.

The HPV vaccine (Gardasil 9) protects against nine HPV types, including the two that cause 70% of cervical cancers and the two that cause 90% of genital warts. The CDC recommends vaccination at age 11 or 12, with catch-up vaccination through age 26. The vaccine is most effective when given before exposure to HPV, which is why the recommendation targets preteens.

Vaccination rates have improved but remain below target. About 62% of adolescents aged 13 to 17 were up to date on HPV vaccination in 2023, according to CDC data. The Healthy People 2030 target is 80%. Among adults aged 18 to 26, completion rates are lower, particularly among those without regular healthcare access.

Cervical cancer screening (through Pap smears and HPV co-testing) is the other pillar of prevention. The combination of HPV vaccination and regular screening has the potential to virtually eliminate cervical cancer within a generation. Australia, which achieved high vaccination coverage early, is on track to be the first country to meet that goal.

Why women bear disproportionate consequences

STIs are biologically asymmetric. Women face greater consequences for several reasons that have nothing to do with behavior and everything to do with anatomy and physiology.

The female reproductive tract has a larger mucosal surface area exposed during intercourse. The cervix and vaginal lining are more susceptible to microtrauma, which creates entry points for pathogens. Younger women are at higher risk partly because the cervical ectropion (the area where columnar cells are exposed on the outer cervix) is larger in adolescents and young adults, creating more vulnerable tissue.

Ascending infection is the critical pathway. In men, chlamydia and gonorrhea typically remain in the urethra and cause obvious symptoms (discharge, pain) that prompt treatment. In women, the same bacteria can ascend silently into the upper reproductive tract, causing endometritis and salpingitis (inflammation of the fallopian tubes) without producing external symptoms until scarring has already occurred.

The downstream consequences are serious. PID affects an estimated 1 million women per year in the United States. Among women who have had PID, 12% experience tubal infertility, 9% have an ectopic pregnancy, and 18% develop chronic pelvic pain. These outcomes are preventable with screening and early treatment — but only if the infections are caught.

During pregnancy, STIs add another layer of risk. Chlamydia and gonorrhea can cause neonatal conjunctivitis and pneumonia. Syphilis can cause stillbirth, organ damage, and death. Herpes simplex can be transmitted during delivery, causing neonatal encephalitis. The consequences of untreated maternal STIs are among the most devastating outcomes in obstetrics.

Screening recommendations by age

The CDC and ACOG screening recommendations vary by age, risk factors, and pregnancy status. Here is what they recommend.

A few practical notes. If you have a new sexual partner, get tested. If your partner has tested positive for an STI, get tested even if you have no symptoms. If you are under 25 and sexually active, your annual well-woman visit should include chlamydia and gonorrhea screening — ask for it if it is not offered. And if you are pregnant or planning to become pregnant, STI screening at the first prenatal visit is non-negotiable.

Tracking your cycle can also help you notice early signs of infection. Unusual bleeding between periods, changes in discharge, or pelvic pain that does not follow your normal pattern are worth reporting to your doctor. Our cycle length calculator and perimenopause guide can help establish what is normal for you.

Disparities in STI burden

STI rates in the United States are not distributed evenly, and the disparities track race, income, and geography in predictable and preventable patterns.

Black women have chlamydia rates approximately five times higher than white women and gonorrhea rates roughly eight times higher, according to CDC 2023 data. These disparities are not explained by differences in sexual behavior. Research consistently shows that the gap is driven by differences in sexual network patterns, access to screening and treatment, poverty concentration, and the higher baseline STI prevalence within segregated communities.

American Indian and Alaska Native women also have disproportionately high rates of chlamydia, gonorrhea, and syphilis. Hispanic women have rates higher than white women for most STIs but lower than Black or AI/AN women.

Geographic disparities compound racial ones. The southern United States accounts for a disproportionate share of STI cases, particularly syphilis and congenital syphilis. This regional concentration aligns with areas of lower insurance coverage, fewer sexual health clinics, and more limited access to prenatal care.

Funding matters. States that invest more in STI prevention infrastructure (public health labs, partner notification services, clinic-based screening) have lower STI rates. The defunding of Title X family planning clinics, which provide STI screening to millions of low-income women annually, has been associated with rises in chlamydia and gonorrhea in affected areas.

Frequently asked questions about STIs in women

What is the most common STI in women?

HPV is the most prevalent STI overall, with about 80% of sexually active people acquiring it in their lifetime. Among bacterial STIs, chlamydia is the most commonly reported, with approximately 1.8 million cases reported to the CDC in 2023. Women under 25 have the highest chlamydia rates, and up to 80% of infections in women produce no symptoms.

Can STIs cause infertility in women?

Yes. Untreated chlamydia and gonorrhea can ascend into the upper reproductive tract and cause pelvic inflammatory disease (PID), which damages the fallopian tubes. After a single episode of PID, about 12% of women experience tubal infertility. After three or more episodes, the infertility rate rises to 40%. Ectopic pregnancy risk also increases six to ten times after PID.

How often should women be screened for STIs?

The CDC recommends annual chlamydia and gonorrhea screening for all sexually active women under 25 and for older women with risk factors such as new or multiple partners. Pregnant women should be screened for chlamydia, gonorrhea, syphilis, HIV, and hepatitis B at the first prenatal visit. Cervical cancer screening (Pap and/or HPV testing) is recommended every 3 to 5 years starting at age 21, depending on the method used.

Why are congenital syphilis cases rising so fast?

Congenital syphilis cases in the U.S. increased more than 900% between 2012 and 2023, driven by rising syphilis rates among women of reproductive age, declining access to prenatal care, and gaps in screening. In 2023, there were over 3,800 congenital syphilis cases and 279 associated stillbirths and infant deaths. Congenital syphilis is preventable with a single penicillin injection, but only if the mother is screened and treated during pregnancy.

Does the HPV vaccine prevent cervical cancer?

The HPV vaccine (Gardasil 9) prevents infection with nine HPV types, including types 16 and 18, which cause approximately 70% of cervical cancers. Persistent high-risk HPV infection causes more than 99% of cervical cancers. Population data from countries with high vaccination coverage show significant reductions in HPV infections, precancerous lesions, and cervical cancer incidence. The CDC recommends vaccination at age 11 or 12, with catch-up doses through age 26.

Are STI rates higher in certain racial groups?

Yes. CDC 2023 data shows that Black women have chlamydia rates about five times higher and gonorrhea rates about eight times higher than white women. American Indian and Alaska Native women also have disproportionately high rates. These disparities are not explained by sexual behavior differences but by structural factors including poverty, healthcare access gaps, sexual network effects, and decades of underinvestment in public health infrastructure in affected communities.