Changes of FHR long term variability (LTV) were studied in four groups of patients under different types of analgesia. The LTV was evaluated according to our visual criteria in each episode of more than one minute of duration on baseline fetal heart rate level between contractions. In the balanced anesthesia group incidence of the episodes with LTV decreased significantly after the administration of Diazepam and Methoxyflurane (64%-30%), further decreasing after the injection of Pethilorfan, but it increased to some degree within 20 min. before delivery. In the epidural group the change of LTV was mild, but the LTV decreased after each administration of 0.25% Bupivacaine (58%-44%-36%). It is also showed mild increase within 20 min. before delivery. Loss of variability was persistently noted until the end of labor from 20-40 min. after the administration of Diazepam and Pentazocine in the modified NLA group. The change in paracervical block group was quite different from the other groups. The incidence of episodes with LTV was increased after the injection of 1% Lidocaine Hydrochloride (35%-41%). There was no significant different of blood gas and acid-base balance among four types of analgesia.