The intent of this article is to provide an overview of the epidemiology and pharmacotherapy, including cost analyses, of Chlamydia trachomatis infections in pregnant women. Chlamydia is a common sexually transmitted infection. For pregnant women, there are concerns both for the mother (post-partum endometritis, horizontal transmission) and the newborn (conjunctivitis, delayed pneumonia). Therapeutic options are restricted because of the fetus and include multi-day treatment with erythromycin, amoxicillin, clindamycin or single dose azithromycin. Clinical cure rates with these options are 86, 92, 93 and 95%, respectively. Pharmacoeconomic analyses have been conducted to determine if the initial increase in acquisition cost of azithromycin (approximately 3-fold higher than erythromycin or amoxicillin) is offset by improvement in compliance and drug efficacy. Clindamycin has received little attention because of its expense (4-fold more than azithromycin). Analyses have been retrospective. As models incorporate more complications of failure to cure, azithromycin increasingly becomes more cost effective and is our recommended treatment.