title: Are pregnancies shorter in leap years?
authors.forename: O
authors.initials: O
authors.lastname: Basso
authors.forename: K
authors.initials: K
authors.lastname: Fonager
authors.forename: J
authors.initials: J
authors.lastname: Olsen
mesh_terms: D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D003718:Denmark; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D012042:Registries; D013997:Time Factors