Chlamydia during pregnancy is common and treatable. Left untreated, it can be passed to your baby at birth and raises the risk of complications, but a safe course of antibiotics clears it. The CDC and USPSTF recommend screening pregnant people, so testing early matters.
| Item | Reported cases |
|---|---|
| Chlamydia | 1,648,568 |
| Gonorrhea | 601,319 |
| Syphilis (P&S) | 53,007 |
Why chlamydia matters in pregnancy
Chlamydia is caused by the bacterium Chlamydia trachomatis, and it's the most commonly reported bacterial STI in the US — roughly 1.65 million reported cases in 2023, a rate of about 492 per 100,000 people CDC AtlasPlus, 2023. It spreads quietly because it's largely a silent infection: about three quarters of infected women and half of infected men have no symptoms at all CDC Chlamydia Fact Sheet.
That silence makes pregnancy a key moment to catch it. You can carry chlamydia for months without a single symptom, then pass it to your baby during a vaginal delivery. When symptoms do appear in women, they include abnormal vaginal discharge and burning on urination; if the infection climbs higher into the reproductive tract, it can cause lower abdominal or low-back pain, fever, pain during intercourse, and bleeding between periods. None of these are reliable warning signs, so screening does the work.
The baby isn't the only reason to treat it. Untreated chlamydia can lead to pelvic inflammatory disease (PID, a deep infection of the uterus and fallopian tubes), fallopian-tube scarring, ectopic pregnancy (a dangerous pregnancy outside the uterus), infertility, and chronic pelvic pain. It can also increase the risk of acquiring or transmitting HIV. A short course of antibiotics now prevents all of that.
What chlamydia can do to the baby
A pregnant person can pass chlamydia to the baby during childbirth, as the baby moves through the birth canal. The bacteria are a leading cause of two newborn problems CDC, About Chlamydia:
- Neonatal conjunctivitis — an eye infection that usually shows up in the first weeks of life as redness, swelling, and discharge, and that can damage the eye if untreated.
- Infant pneumonia — a lung infection that tends to appear a little later in the first months, often as a persistent cough and breathing trouble without much fever.
Both are treatable when caught, and both are far easier to avoid by clearing the mother's infection before delivery. Screening during pregnancy means finding it, treating it, and confirming it's gone.
When you should be screened in pregnancy
The USPSTF (its September 14, 2021 recommendation, a Grade B) advises screening all sexually active women 24 or younger and women 25 and older who are at increased risk, and that explicitly includes pregnant people USPSTF, 2021. In practice, most clinicians order a chlamydia test at the first prenatal visit. If you're 24 or under, or have a new or multiple partners, you'll likely be retested in the third trimester so a late infection doesn't slip through to delivery.
The screening guidance is deliberately asymmetric: a strong "screen" for younger women but an insufficient-evidence statement for men, because the complication burden of PID, infertility, and the risks to a pregnancy falls on women. If you'd like to understand how the test itself works (a simple urine sample or swab, no fasting, results in days), see our explainer on chlamydia testing & diagnosis, and if you're trying to time a test around a specific exposure, check when to test after exposure. You can also get tested without a referral in most areas.
Safe treatment during pregnancy
The first-line treatment outside pregnancy is doxycycline 100 mg orally twice daily for 7 days CDC STI Treatment Guidelines, 2021. Doxycycline isn't used in pregnancy, so the recommended option for pregnant people is different.
In pregnancy, the preferred regimen is azithromycin 1 g orally as a single dose, with amoxicillin 500 mg three times daily for 7 days as an alternative. Both are considered safe in pregnancy, and the single-dose azithromycin is convenient — you can take it in the clinic and be done.
| Situation | Recommended regimen |
|---|---|
| Pregnant — preferred | Azithromycin 1 g orally, single dose |
| Pregnant — alternative | Amoxicillin 500 mg three times daily for 7 days |
| Not pregnant — first-line | Doxycycline 100 mg twice daily for 7 days |
In non-pregnant people, azithromycin was downgraded from a co-equal option because microbiologic treatment failure in men was higher than with doxycycline, and doxycycline cures rectal infection far better. One randomized trial found 100% cure with doxycycline versus 74% with azithromycin Rectal CT RCT. So doxycycline is first-line generally, while azithromycin remains the pregnancy-safe choice for genital infection.
Pregnancy is also the one situation where a test-of-cure is recommended: get retested about 4 weeks after finishing treatment to confirm the infection cleared, and then again at about 3 months to catch chlamydia reinfection. For everyone else, a test-of-cure isn't routinely advised unless adherence is in question, symptoms persist, or reinfection is suspected, though the 3-month retest still applies because reinfection is common.
Reducing transmission at delivery
The single most effective way to protect the baby is to clear the mother's infection before delivery, which is why the test-of-cure timeline matters. If chlamydia is treated and confirmed negative before labor, the transmission risk during a vaginal birth drops dramatically.
Treating partners matters as much as treating yourself, because reinfection is the most common reason treatment seems to "fail." Partners from the prior 60 days should be referred, tested, and presumptively treated, and you should abstain from sex for 7 days after single-dose therapy (or until a 7-day course is finished) so you don't pass it back and forth. Expedited partner therapy (EPT) — giving you medication to hand to your partner — measurably cuts repeat infection; in a landmark trial it reduced persistent or repeat infection, with the biggest benefit seen for gonorrhea (3% vs 11%) EPT RCT, NEJM. EPT is permissible in most but not all US states, so verify your local status. An untreated male partner keeps reinfecting everyone in the chain, one way chlamydial urethritis can lead to painful health complications for men.
When to see a clinician
Book a visit if you're pregnant and haven't been screened yet, if you have a new or untreated partner, or if you notice abnormal discharge, burning on urination, pelvic pain, fever, or bleeding between periods. Any newborn with eye redness and discharge or a persistent cough in the first months should be evaluated promptly. And because chlamydia and other STIs travel together, anyone diagnosed should also be offered HIV testing.
A practical note on what treatment is actually like: take antibiotics exactly as prescribed, make sure your partner is treated at the same time to avoid "ping-pong" reinfection, and put your retest date in your calendar before you leave the appointment. Condoms every time help, but since most infections are silent, routine screening and treating partners do the heavy lifting.