[Study of painless labor].
D000136:Acid-Base Equilibrium; D000328:Adult; D000700:Analgesics / Q000627:therapeutic use; D000773:Anesthesia, Obstetrical; D005260:Female; D006801:Humans; D009321:Natural Childbirth; D010146:Pain; D011247:Pregnancy
D000700:Analgesics