title: Pregnancy complications in acquired thrombotic thrombocytopenic purpura: a case-control study.
abstract: BACKGROUND
  Pregnant women with a history of acquired thrombotic thrombocytopenic purpura (TTP) are considered at risk for disease recurrence and might be at risk for miscarriage, similar to other autoimmune disorders. However, the exact entity of these risks and their causes are unknown. The aim of this study was to evaluate risk factors associated with adverse pregnancy outcome, in terms of both gravidic TTP and miscarriage, in women affected by previous acquired TTP.
  
  
  METHODS
  We conducted a nested case-control study in women with a history of acquired TTP enrolled in the Milan TTP registry from 1994 to October 2012, with strict inclusion criteria to reduce referral and selection bias.
  
  
  RESULTS
  Fifteen out of 254 women with acquired TTP were included, namely four cases with gravidic TTP, five with miscarriage, and six controls with uncomplicated pregnancy. In the cases, ADAMTS13 activity levels in the first trimester were moderately-to-severely reduced (median levels <3% in gravidic TTP and median levels 20% [range 14-40%] in the women with miscarriage) and anti-ADAMTS13 antibodies were invariably present, while in the control group ADAMTS13 activity levels were normal (median 90%, range 40-129%), with absence of detectable anti-ADAMTS13 antibodies. Reduced levels of ADAMTS13 activity (<25%) in the first trimester were associated with an over 2.9-fold increased risk for gravidic TTP and with an over 1.2-fold increased risk for miscarriage (lower boundary of the confidence interval of the odds ratio). In addition, the presence of anti-ADAMTS13 antibodies during pregnancy was associated with an over 6.6-fold increased risk for gravidic TTP and with an over 4.1-fold increased risk for miscarriage.
  
  
  CONCLUSIONS
  ADAMTS13 activity evaluation and detection of anti-ADAMTS13 antibody could help to predict the risk of complications in pregnant women with a history of acquired TTP.
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. barbara.ferrari@policlinico.mi.it.
authors.forename: Barbara
authors.initials: B
authors.lastname: Ferrari
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. alberto.maino@gmail.com.
authors.forename: Alberto
authors.initials: A
authors.lastname: Maino
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. luca.lotta@guest.unimi.it.
authors.forename: Luca A
authors.initials: LA
authors.lastname: Lotta
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. andrea.artoni@policlinico.mi.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Artoni
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. silviapontiggia@alice.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pontiggia
authors.affiliation: Cellular Biotechnologies and Hematology, Sapienza University, Rome, Italy. trisolini@bce.uniroma1.it.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Trisolini
authors.affiliation: UOC di Ematologia con UTMO, Ospedali Riuniti Villa Sofia-Cervello, Palermo, Italy. alessandramalato@hotmail.com.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Malato
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. F.R.Rosendaal@lumc.nl.|Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands. F.R.Rosendaal@lumc.nl.|Department of Thrombosis and Haemostasis, Leiden University Medical Center, Leiden, The Netherlands. F.R.Rosendaal@lumc.nl.
authors.forename: Frits R
authors.initials: FR
authors.lastname: Rosendaal
authors.affiliation: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Milan, Italy. flora.peyvandi@unimi.it.|Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy. flora.peyvandi@unimi.it.
authors.forename: Flora
authors.initials: F
authors.lastname: Peyvandi
mesh_terms: D051722:ADAM Proteins / Q000235:genetics*; D000071120:ADAMTS13 Protein; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000175:diagnosis* / Q000235:genetics*; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis* / Q000235:genetics*; D055815:Young Adult
chemical_list: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human