title: Mid-pregnancy, perinatal, and neonatal reproductive endocrinology: a prospective cohort study in twins and singleton control subjects.
abstract: OBJECTIVE
  To answer the questions: Are perinatal reproductive hormone profiles different in case of a twin compared with a singleton pregnancy? Are reproductive endocrine profiles of twin girls influenced by their male co-twin and vice versa?
  
  
  METHODS
  Prospective cohort study from January 2004 to October 2009.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  A total of 204 mothers of twins and 248 singleton control subjects, aged >18 years, pregnant with a twin or singleton and no endocrine disease or malignancy.
  
  
  METHODS
  Blood samples were collected at mid-gestation from the mother and at delivery from the mothers and the umbilical cords. Estrogens, androgens, sex hormone-binding globulin, progesterone, and gonadotropins were measured.
  
  
  METHODS
  Hormonal profiles were compared between singletons and twins, different types of twins, and opposite-sex and same-sex twins.
  
  
  RESULTS
  Estrogen and progesterone concentrations were higher in mothers of twins compared with singletons, but twin babies had lower estrogen and progesterone concentrations at birth. Opposite-sex twin girls did not have higher androgens in cord blood compared with same-sex twin girls. Boys of an opposite-sex twin had lower luteinizing hormone concentrations compared with dizygotic twin boys with a brother as a co-twin.
  
  
  CONCLUSIONS
  Children from a twin are not overexposed to sex steroids at the time of birth, despite higher concentrations in their mothers, and girls from opposite sex twins do not show androgenic influences from their male co-twin. The female co-twin may influence the hypothalamic-pituitary-testicular axis of her brother via central inhibition.
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands. Electronic address: e.kuijper@vumc.nl.
authors.forename: Esther A M
authors.initials: EA
authors.lastname: Kuijper
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Jos W R
authors.initials: JW
authors.lastname: Twisk
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Ted
authors.initials: T
authors.lastname: Korsen
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Mirte R
authors.initials: MR
authors.lastname: Caanen
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah; Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Kushnir
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah; Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Rockwood
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah; Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
authors.forename: A Wayne
authors.initials: AW
authors.lastname: Meikle
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Hompes
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Wit
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Cornelis B
authors.initials: CB
authors.lastname: Lambalk
mesh_terms: D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004967:Estrogens / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D006062:Gonadotropins / Q000097:blood; D006728:Hormones / Q000097:blood*; D006801:Humans; D008297:Male; D036801:Parturition / Q000097:blood; D011247:Pregnancy; D059285:Pregnancy, Twin / Q000097:blood*; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D004967:Estrogens; D006062:Gonadotropins; D006728:Hormones; D012738:Sex Hormone-Binding Globulin; D011374:Progesterone
keywords: Estrogens; androgens; pregnancy; twins