title: [Vitamin D concentrations are decreased in singleton and twin pregnancies].
authors.affiliation: Servicio de Obstetricia y Ginecología, Hospital Universitario La Paz, Madrid, España. Electronic address: maria.delacalle@uam.es.
authors.forename: María
authors.initials: M
authors.lastname: de la Calle
authors.affiliation: Servicio de Reumatología, Hospital Universitario La Paz, Madrid, España.
authors.forename: Sara
authors.initials: S
authors.lastname: García
authors.affiliation: Servicio de Laboratorio, Hospital Universitario La Paz, Madrid, España.
authors.forename: Marta
authors.initials: M
authors.lastname: Duque
authors.affiliation: Servicio de Obstetricia y Ginecología, Hospital Universitario La Paz, Madrid, España.
authors.forename: José L
authors.initials: JL
authors.lastname: Bartha
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D059285:Pregnancy, Twin; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control