Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. Many infected individuals, particularly women, experience no noticeable symptoms, making the infection easy to overlook without routine screening. When chlamydia occurs during pregnancy, it poses distinct risks to both the pregnant person and the developing baby. Fortunately, these potential complications are largely preventable through accessible testing and safe antibiotic treatment during prenatal care.
Effects on the Mother’s Pregnancy
An active chlamydial infection in the lower genital tract initiates an inflammatory response that negatively impacts the course of the pregnancy. This inflammation is associated with a breakdown of membranes and tissues, increasing the risk of the pregnant person’s water breaking before labor begins.
This condition is known as premature rupture of membranes (PROM). PROM removes the protective barrier around the fetus and often necessitates an early delivery. Untreated maternal chlamydia infection may increase the risk for preterm labor and delivery by as much as two to four times. Delivering the baby before 37 weeks of gestation contributes to the risk of low birth weight, which is associated with various health issues for the newborn.
An untreated chlamydial infection can also increase the risk of postpartum endometritis, a uterine infection involving inflammation of the uterine lining after birth. This condition requires prompt antibiotic intervention to prevent severe complications for the mother. Screening and treatment during pregnancy are effective measures to reduce the likelihood of these adverse gestational and postpartum events.
Immediate Risks to the Newborn
If a pregnant person has an active, untreated chlamydial infection at the time of delivery, the newborn risks acquiring the bacteria during passage through the birth canal. This vertical transmission can lead to two main types of infection: chlamydial conjunctivitis and chlamydial pneumonia. It is estimated that 30 to 50 percent of exposed infants will develop an eye infection.
Chlamydial conjunctivitis, also known as neonatal ophthalmia, typically develops five to fourteen days after birth, which is a later onset than other bacterial eye infections. The infection presents with swollen eyelids and a discharge that is often watery at first, becoming thicker and mucopurulent over time. If left untreated, the infection can cause scarring of the cornea and conjunctiva, potentially leading to vision impairment.
The second major risk is chlamydial pneumonia, which usually appears between four and twelve weeks of the baby’s life. This respiratory infection is characterized by a distinctive, repetitive staccato cough, often without an accompanying fever. The infant may also show signs of congestion and wheezing. This condition requires specific oral antibiotic treatment because topical antibiotics used for the eye infection do not eliminate the bacteria from the respiratory system. Approximately 10 to 20 percent of exposed infants will develop this type of pneumonia.
Screening and Management During Pregnancy
Early and effective intervention is the most reliable way to prevent chlamydia-related complications for both the pregnant person and the baby. Current medical guidelines recommend screening for Chlamydia trachomatis at the first prenatal visit. Screening is especially important for individuals under 25 years old and those with risk factors, such as a new sexual partner or multiple partners.
For high-risk individuals, a repeat screening is often recommended during the third trimester to account for potential reinfection. A positive test result is treated immediately with an antibiotic regimen safe for the fetus, such as a single dose of azithromycin or a course of amoxicillin. These medications effectively eradicate the bacterium without posing risks to the developing baby.
Following treatment, a “test of cure” is performed approximately four weeks later to ensure the infection has cleared completely. The pregnant person’s sexual partner must also be tested and treated. Failure to treat the partner creates a high risk of reinfection, which would negate the treatment and place the pregnancy back at risk.