Drinking black coffee is not recommended during breastfeeding, which may affect postpartum sleep, affect the baby’s state and so on. 1. Affecting postpartum sleep: As black coffee contains caffeine, it may lead to nerve excitation, which may affect the postpartum sleep of the mother, resulting in poor sleep and poor mental state. 2. Affecting the baby’s state: if the mother drinks black coffee during breastfeeding, the caffeine in it is likely to enter the breast milk, and when the baby eats it, it is likely to cause the baby to be irritable and nervous, and even affect the baby’s sleep. Therefore, it is not recommended to drink black coffee when breastfeeding, in addition, do not smoke and drink alcohol, drink strong tea, to avoid the impact on themselves or their babies.