Length of labor and sex of offspring.
D000700:Analgesics / Q000627:therapeutic use; D000773:Anesthesia, Obstetrical; D001722:Birth Order; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007743:Labor, Obstetric; D008297:Male; D011247:Pregnancy; D012737:Sex Factors; D013997:Time Factors
D000700:Analgesics