From the Guidelines

Chlamydia infection during labor is associated with adverse pregnancy outcomes, including preterm labor, low birth weight, and infant mortality.

The implications of Chlamydia infection during labor are significant, and can lead to:

Preterm labor: Chlamydia infection during pregnancy is associated with an increased risk of preterm labor, which can lead to low birth weight and infant mortality 1.
Low birth weight: Chlamydia infection during pregnancy can also lead to low birth weight, which can increase the risk of infant mortality and other health problems 1.
Infant mortality: Chlamydia infection during pregnancy can increase the risk of infant mortality, which can have devastating consequences for the family and community 1.
Neonatal chlamydial infection: Chlamydia infection during labor can also lead to neonatal chlamydial infection, which can cause inclusion conjunctivitis, subacute pneumonia, and rectogenital infections 1.

Screening for Chlamydia infection during pregnancy is crucial to prevent adverse pregnancy outcomes.

Pregnant women at increased risk: Pregnant women at increased risk, such as those under 25 years of age or with new or multiple sex partners, should be screened for Chlamydia infection during the first trimester or third trimester 1.
Treatment: Treatment of Chlamydia infection during pregnancy can improve pregnancy outcomes and prevent neonatal chlamydial infection 1.

Prevention of Chlamydia infection during pregnancy is key to preventing adverse pregnancy outcomes.

Safe sex practices: Practicing safe sex, such as using condoms, can help prevent Chlamydia infection during pregnancy 1.
Screening and treatment of partners: Screening and treatment of partners can also help prevent Chlamydia infection during pregnancy 1.

From the Research

Chlamydia trachomatis infection during labor can be transmitted to the newborn, causing ophthalmia neonatorum and atypical neonatal pneumonia 2.
There is evidence that chlamydial infection during pregnancy may contribute to adverse complications such as premature rupture of membranes, preterm labor and birth, low birth weight, and still birth 3.
Chlamydia infections during pregnancy are associated with small, but statistically significant, increased odds of preterm birth, early preterm birth, low birthweight, congenital anomalies, low 5-min Apgar score, neonatal intensive care unit admission, immediate neonatal ventilation, prolonged neonatal ventilation, and neonatal antibiotic treatment for suspected sepsis 4.
However, some studies have found no significant association between a positive test for chlamydia and spontaneous preterm birth, a baby who is small for gestational age, or stillbirth, particularly if the infection is diagnosed and treated during or before pregnancy 5.

Women with chlamydia infections during pregnancy are at increased risk of adverse perinatal outcomes, including preterm birth, low birthweight, and congenital anomalies 4.
The incidence of Chlamydia trachomatis in women with threatened preterm labor is approximately 9%, and significantly increased compared to asymptomatic controls 6.
Chlamydia trachomatis infections have been associated with preterm prelabor rupture of membranes and preterm birth 6.

Routine screening for young women and screening during pregnancy is recommended in several countries to reduce the spread of chlamydial infection 2.
Women with threatened preterm labor should be considered for screening for Chlamydia trachomatis 6.
Treatment of chlamydial infection during pregnancy has proved beneficial in the prevention of neonatal morbidity and is now recommended by the Centers for Disease Control 3.