The changing incidence of twinning: one century of Italian statistics.
D000328:Adult; D001723:Birth Rate; D003710:Demography; D005260:Female; D006801:Humans; D007558:Italy; D008423:Maternal Age; D010060:Ovulation / Q000187:drug effects; D010298:Parity; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011783:Quadruplets; D011811:Quintuplets; D014310:Triplets; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic