Lochia is the vaginal discharge composed of  blood, mucus, and uterine tissue, that occurs after giving birth. Lochia discharge typically continues for 4 to 6 weeks after childbirth, which is known as the postpartum period.

It is sterile for the first 2 to 3 days, but not so by the third or fourth day, as the uterus begins to be colonized by vaginal commensals such as non-hemolytic streptococci and E. coli.

It progresses through three stages:

Lochia rubra (or cruenta) is the first discharge, Composed of blood, shreds of fetal membranes, decidua, vernix caseosa, lanugo and membranes. It is red in color because of the large amount of blood it contains. It typically lasts no longer than 3 to 5 days after birth.

Lochia serosa is the term for lochia that has thinned and turned brownish or pink in color. It contains serous exudate, erythrocytes, leukocytes, cervical mucus and microorganisms. This stage continues until around the tenth day after delivery. Lochia serosa which persists to some weeks after birth can indicate late postpartum hemorrhaging, and should be reported to a physician.

Lochia alba (or purulenta) is the name for lochia once it has turned whitish or yellowish-white. It typically lasts from the second through the third to sixth weeks after delivery. It contains fewer red blood cells and is mainly made up of leukocytes, epithelial cells, cholesterol, fat, mucus and microorganisms. Continuation beyond a few weeks can indicate a genital lesion, which should be reported to a physician.