Chlamydia is a common STD among both men and women. It can damage a woman’s reproductive system, making pregnancy difficult. Chlamydia can also cause a pregnancy that occurs outside the womb or can be passed to your baby during delivery, causing eye infection or pneumonia in your newborn. If you are pregnant, you should receive testing for chlamydia at your first prenatal visit. A positive result of Chlamydia trachomatis IgG indicates past, current, or chronic infection, while positive IgM antibodies show recent infection.