Effects of some recent intramuscular analgesics on labour pain and maternal and fetal blood gases and pH

This study attempted to determine the analgesic properties of pentazocine hydrochloride, nalbuphine hydrochloride, butarphanol tartarate and tramadol hydrochloride given during labor and their potential effects on maternal and fetal blood gases and pH. Tramadol and butarphanol analgesics were superior to either nalbuphine or pentazocine in relieving labor pain. The studied analgesics caused maternal respiratory acidosis and fetal metabolic acidosis and these acidetic changes were marked with pentazocine, moderate with nalbuphine and minimal with butarphanol and tramadol analgesia