What are the classifications of postpartum lochia?

Lochia after childbirth is the vaginal discharge composed of shed uterine decidua and blood following delivery. Based on its color, characteristics, and duration, lochia is mainly classified into the following three types: **Bloody lochia**: Typically appears on days 1–4 postpartum. It is bright red in color and contains a large amount of blood, sometimes with small clots, as well as small amounts of fetal membranes, vernix caseosa, and necrotic decidual tissue. Its duration is generally 3–4 days, with volume similar to or slightly more than that of a menstrual period. **Serous lochia**: Discharged between days 4 and 10 postpartum, it is pinkish-red and contains a small amount of blood, more necrotic decidual tissue, mucus, and bacteria. It usually lasts for about 10 days. **White lochia**: Begins around day 10 postpartum, appearing white or pale yellow, with a thick, sticky consistency. It contains large numbers of white blood cells, epithelial cells, necrotic decidual tissue, and bacteria. This type typically persists for approximately three weeks until lochia resolves completely. The duration and composition of lochia may vary among individuals, but generally follow the above classification and pattern. If lochia lasts longer than expected or is excessively heavy, prompt medical evaluation is recommended.