The precursors of menstruation during lactation are basically the same as the usual precursors of menstruation, including increased vaginal discharge, breast swelling and pain, lumbosacral pain, mood swings and other systemic symptoms: 1. Increased vaginal discharge: before menstruation, increased vaginal discharge can occur, and the color of the leucorrhoea is yellow, and some women will have a small amount of brown discharge; 2. Before the onset of menstruation, the estrogen and progesterone levels in a woman’s body rise significantly, which can lead to breast swelling and pain, mainly at the outer edge of the breast and the nipple area. When the hormone level decreases, this symptom can be gradually reduced; 3. Lumbosacral pain: Before menstruation, the pelvic tissues are easily congested, which can lead to lumbosacral pain and pelvic swelling; 4. Emotional fluctuation: Before menstruation, it is easy to have irritable moods, arguing and crying over small things in life, and it is difficult to control oneself; 5. Other systemic symptoms: Skin acne, general weakness, drowsiness and other symptoms can appear. For women who have premenstrual symptoms during breastfeeding, they should keep their mood relaxed and get enough sleep in order to facilitate regular menstrual cycle.