This chapter deals with genital chlamydial infections in pregnancy and postpartum. There is increasing evidence that Chlamydia trachomatis infection may result in a number of adverse pregnancy outcomes, including early and late abortion, intrauterine infections of the fetus, stillbirth, prematurity, premature rupture of the membranes (PROM) and postpartum endometritis. Ectopic pregnancy is commonly associated with a previous tubal chlamydial infection where immunological reactions seem to play a role. C. trachomatis infection may be acquired as an intrauterine infection, as well as during transit through the birth channel, and this may result in neonatal conjunctivitis and/or pneumonia. The role of chlamydial infection in the sudden death syndrome has also been considered, but evidence so far is minimal. Neonatal chlamydial infection may cause life-long sequelae, such as obstructive lung disease. Genital chlamydial infections have been associated with problems in insemination and attempts at in vitro fertilization. The chapter also deals with screening of pregnant women for C. trachomatis and the treatment of infected mothers and their offspring.