Chlamydia and Pregnancy: Risks, Treatment, and Screening

Quick Answer: Chlamydia during pregnancy can lead to premature birth, low birth weight, and transmission to the baby during delivery — potentially causing neonatal conjunctivitis or pneumonia. The good news: chlamydia is easily treated with pregnancy-safe antibiotics, and early screening at your first prenatal visit can prevent complications entirely.

How Does Chlamydia Affect Pregnancy?

Untreated chlamydia during pregnancy poses real risks to both mother and baby. Research from the NIH shows that pregnant women with active chlamydia infections have higher rates of preterm delivery, premature rupture of membranes, and low birth weight. There is also an increased risk of postpartum endometritis — infection of the uterine lining after delivery.

In my clinical experience, the most concerning complication is vertical transmission: the passage of chlamydia from mother to baby during vaginal delivery. This occurs in approximately 50% of vaginal births to mothers with untreated chlamydia, according to published estimates.

What Happens if a Baby Is Exposed to Chlamydia?

Newborns who contract chlamydia during delivery can develop two primary conditions:

• Neonatal conjunctivitis (ophthalmia neonatorum) — an eye infection that typically appears 5 to 14 days after birth, causing redness, swelling, and discharge from the eyes. Without treatment, it can damage the cornea

• Chlamydial pneumonia — a lung infection that may develop 1 to 3 months after birth, causing a distinctive staccato cough, congestion, and rapid breathing

Both conditions are treatable with antibiotics, but prevention through maternal screening and treatment is far preferable.

Is Chlamydia Treatment Safe During Pregnancy?

Yes — but the choice of antibiotic matters. Doxycycline, the standard first-line treatment for chlamydia, is contraindicated in pregnancy because tetracycline antibiotics can affect fetal bone and tooth development. The CDC recommends the following pregnancy-safe options:

• Azithromycin 1 gram — single oral dose (preferred in pregnancy)

• Amoxicillin 500 mg — three times daily for 7 days (alternative)

For more details on available medication options, see the chlamydia treatment guide. For context on whether amoxicillin treats chlamydia, see our dedicated article. Pregnant patients should also be retested approximately 4 weeks after completing treatment, and again in the third trimester, to confirm the infection has cleared.

When Should Pregnant Women Get Tested?

The American College of Obstetricians and Gynecologists and the CDC recommend chlamydia screening for all pregnant women at the first prenatal visit, regardless of age or risk factors. Additional testing in the third trimester is recommended for women under 25, those with a new sexual partner, or anyone with risk factors for STIs.

Early detection makes a significant difference. When chlamydia is identified and treated before delivery, the risk of transmission to the baby drops to essentially zero. You can get tested for chlamydia confidentially at any point during pregnancy. A full STI panel is recommended at the first prenatal visit to screen for HIV, syphilis, and other infections simultaneously.

Can Chlamydia Cause Infertility That Affects Future Pregnancies?

If left untreated for an extended period, chlamydia can ascend to the fallopian tubes and cause pelvic inflammatory disease (PID). PID can lead to scarring of the fallopian tubes, increasing the risk of ectopic pregnancy and tubal-factor infertility. This is why screening and treatment — whether or not you are currently pregnant — is so important for reproductive health.

When to Seek Urgent Care

• You are pregnant and develop pelvic pain, fever, or unusual vaginal discharge — these may indicate ascending infection or PID

• You experience premature contractions, fluid leaking, or signs of preterm labor

• Your newborn develops red, swollen eyes with discharge within the first two weeks of life

• Your infant develops a persistent cough or breathing difficulties in the first few months

• You are pregnant and a partner discloses a chlamydia diagnosis — get tested and treated immediately

Frequently Asked Questions

Can I get pregnant if I have had chlamydia?

In most cases, yes. If chlamydia was treated before it caused PID or tubal damage, your fertility should be unaffected. However, repeated or prolonged untreated infections do increase the risk of fertility complications. If you have had chlamydia and are having difficulty conceiving, discuss your history with a reproductive specialist.

Does chlamydia always pass to the baby during delivery?

No. Transmission occurs in roughly 50% of vaginal deliveries to infected mothers. Treatment before delivery eliminates this risk entirely. Cesarean delivery may be considered in certain circumstances but is not routinely recommended solely for chlamydia prevention.

Can chlamydia cause miscarriage?

Some research suggests an association between untreated chlamydia and increased miscarriage risk, though the evidence is not conclusive. What is clear is that untreated chlamydia increases the risk of other pregnancy complications, making early treatment the safest approach.

My partner has chlamydia — what should I do during pregnancy?

Get tested immediately and begin treatment if positive. Your partner must also complete treatment before you resume sexual contact. Retest approximately 4 weeks after treatment and again in the third trimester. Learn more about chlamydia incubation periods to understand testing timing.