One of the most common infectious complications during pregnancy, it occurs when lower genital tract microorganisms (e.g., chlamydia trachomatis, gonorrhoea) from the vagina or cervix ascend to infect or cause inflammation of the amniotic fluid, placenta, choriodecidua, chorioamnion, or uterus. It is associated with an increased risk of preterm labor/delivery. In US women aged 20-65 years, about 20% suffer one urinary tract infection per year.
See Amnion (or amniotic sac), Amniotic fluid, Chorion, Placenta, Preterm birth,