Frequency of twinning in California. Its relationship to maternal age, parity and race.
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D044466:Asian People; D002140:California; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014427:Twins; D044465:White People