The criterion of relevance.
D002648:Child; D002662:Child Health Services; D003153:Community Health Services; D005260:Female; D006285:Health Planning; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008427:Maternal Health Services; D008880:Midwifery; D011247:Pregnancy; D011637:Public Health Nursing; D014481:United States