Chlamydia is the most frequently reported bacterial sexually transmitted infection (STI). The presence of an infection with Chlamydia trachomatis during pregnancy can introduce a series of complications for both the pregnant individual and the developing fetus. This common infection is often asymptomatic, meaning many people are unaware they are carrying the bacteria. While easily treated with antibiotics, an untreated infection during gestation increases pregnancy risks. Routine screening is a standard part of prenatal care to ensure immediate detection and management.
How Chlamydia Affects the Pregnant Individual
An active chlamydial infection can ascend from the cervix into the upper reproductive tract, creating inflammation that directly impacts the pregnancy environment. This ascending infection is associated with an increased likelihood of premature rupture of membranes (PPROM), or the water breaking early. PPROM removes the protective barrier around the fetus and increases the chance of uterine infection.
The inflammatory response triggered by the bacteria also raises the risk of preterm delivery, defined as delivery before 37 weeks of gestation. Studies indicate that chlamydial infection may be linked to a significantly increased risk of very early premature delivery. Furthermore, some data suggest an association between chlamydia and lower mean birth weight, independent of prematurity.
Following delivery, the pregnant person remains susceptible to complications stemming from the infection. Postpartum endometritis, an infection of the uterine lining after birth, is an adverse outcome associated with untreated chlamydia. This condition requires further medical intervention and can complicate the recovery period.
Risks of Transmission to the Newborn
The primary concern regarding chlamydia in pregnancy is the high risk of vertical transmission to the newborn. Transmission typically occurs as the baby passes through the infected birth canal during a vaginal delivery. If the pregnant person is untreated at the time of birth, the transmission rate can be as high as 50% to 60%.
Newborns who contract C. trachomatis are at risk for developing two main conditions: neonatal conjunctivitis and chlamydial pneumonia. Neonatal conjunctivitis, also called ophthalmia neonatorum, is an eye infection that manifests as discharge, redness, and swelling. This condition usually appears a few days to several weeks after birth, affecting between 25% and 50% of infected infants.
Chlamydial pneumonia is a serious respiratory infection that generally has an insidious onset, often appearing between four and twelve weeks after delivery. The pneumonia is characterized by a distinctive repetitive, staccato cough and rapid breathing, but is often afebrile (without fever). Approximately 5% to 30% of infants infected during birth will develop this form of pneumonia. While both conditions are treatable with antibiotics, untreated infection can persist and potentially lead to long-term health issues.
Screening Guidelines and Safe Treatment During Pregnancy
Medical guidelines recommend universal screening for C. trachomatis for all pregnant individuals at their first prenatal visit. This initial test is usually performed using a nucleic acid amplification test (NAAT) on a urine sample or a self-collected vaginal swab. Repeat screening is advised during the third trimester for individuals under 25 years old or those with other risk factors, due to the risk of re-exposure and reinfection.
Prompt treatment is essential to prevent both maternal and neonatal complications. The preferred first-line antibiotic regimen during pregnancy is Azithromycin, administered as a single 1-gram oral dose. Azithromycin is highly effective and safe for use in pregnancy.
An alternative treatment option is Amoxicillin, given as 500 milligrams orally three times a day for seven days. Other common chlamydia treatments, such as Doxycycline, are contraindicated in pregnancy due to the risk of fetal harm. Following treatment, a “test of cure” is recommended 3 to 4 weeks later to confirm the infection has been eradicated. Retesting is also advised approximately three months after treatment to check for reinfection.