title: Motherhood and childlessness in monozygous twins. I. Early relationships.
mesh_terms: D000328:Adult; D005260:Female; D005306:Fertilization; D006801:Humans; D008875:Middle Aged; D010063:Ovum; D010287:Parent-Child Relations; D010298:Parity; D010553:Personality Development; D011247:Pregnancy; D012801:Sibling Relations; D012930:Social Dominance; D014427:Twins