The twinning connection.
D000818:Animals; D005260:Female; D005298:Fertility; D006736:Horses / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood; D010060:Ovulation; D011247:Pregnancy; D011270:Pregnancy, Animal; D011272:Pregnancy, Multiple; D014427:Twins
D007986:Luteinizing Hormone