Epidural butorphanol tartrate in painless labour.
D000328:Adult; D000767:Anesthesia, Epidural; D000773:Anesthesia, Obstetrical; D002077:Butorphanol; D005260:Female; D006801:Humans; D009019:Morphinans; D011247:Pregnancy
D009019:Morphinans; D002077:Butorphanol