Painless labor injection to open to three fingers after the instructions formally into the labor process, so open three fingers before playing painless labor injection. 1. Before the opening of the three fingers: before the opening of the three fingers of the mother, the pain symptoms are not too serious, pregnant women can tolerate, because the pain is intermittent, this time the pain of a short period of time, the rest of the time is long. And usually this period has not formally entered the labor process, do not need to play painless injection. 2. After the opening of the third finger: after the opening of the third finger, the pain symptoms worsen, the pain time is long, the rest time is short, if the pain is graded, the pain symptoms at this time will reach more than 6-7 levels. If you grade the pain, the pain will reach level 6-7 or above. And at this time, the labor process has already been officially entered, so the labor injection usually starts from this time. The painless labor method can reduce the pain symptoms of the mother and is a medically recognized method of delivery, but the delivery injection also carries some risks and is used under the supervision of a doctor.