The full term uterus has grown at least ten times bigger than it was before pregnancy. On its own it weighs approximately 1kg (not including the baby, placenta, amniotic fluid, etc), whereas its pre-pregnant weight was only 50-100 gm. Immediately after the baby is born, the uterus can be palpated at or near the woman’s umbilicus (belly button), as it contracts to expel the placenta and fetal membranes. It normally shrinks to its non-pregnant size during the first six weeks after delivery, but most of the reduction in size and weight occurs in the first two weeks. At around this time, the uterus should have shrunk enough to be located in the woman’s pelvis, below her umbilicus.
The inner lining of the uterus (the endometrium) rapidly heals after the birth, so that by the seventh day, it is restored throughout the uterus, except at the placental site. The inside of the uterus, where the placenta was attached, undergoes a series of changes which reduce the number of blood capilliaries entering that site. The capilliaries that remain ‘leak’ blood plasma for a time, which results in a normal vaginal discharge called lochia. This discharge often continues for several weeks after the birth. In the first week, the lochia is bloody and brownish red, but it gradually changes over time to a more watery consistency. Over a period of two to three weeks, the discharge continues to decrease in amount and the colour changes to pale yellow (straw coloured). The period of time the lochia continues varies, with an average duration of around five weeks, with a waxing and waning amount of flow and colour. Each woman has her own pattern, with the various phases of the lochia lasting for different lengths of time.