title: The Impact of Twin Birth on Early Neonatal Outcomes.
abstract: OBJECTIVE
  This study aims to describe the impact of twin birth, chorionicity, intertwin birth weight (BW) discordance and birth order on neonatal outcomes.
  
  
  METHODS
  We performed a hospital-based retrospective study on 2,170 twins (6.4% of all live births) and 2,217 singletons inborn 2007 to 2011. Data on neonatal characteristics, morbidities, and mortality were collected and compared. Univariate and multiple (adjusted for gestational age [GA] and gender) linear random intercept regression models were used.
  
  
  RESULTS
  Overall, 62.3% of twins were born premature. At multiple regression, twins were similar to singletons for neonatal morbidities, but they were more likely to have lower BW and to be born by cesarean delivery. Monochorionic twins had lower GA and BW compared with dichorionic ones and were more likely to develop respiratory distress syndrome (odds ratio [OR], 1.7), hypoglycemia (OR, 3.3), need for transfusion, (OR, 3.4) but not brain abnormalities. Moderate and severe BW discordance were associated with longer length of stay and increased risk for morbidities but not for death. Birth order had no effects.
  
  
  CONCLUSIONS
  Prematurity was the most common outcome in twins and accounted for the apparently increased risk in morbidities. Monochorionicity was confirmed as risk factor for lower GA and neonatal morbidities. BW discordance may play a role in developing neonatal complications and needs to be further investigated.
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Fumagalli
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Schiavolin
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bassi
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Groppo
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Uccella
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Agnese
authors.initials: A
authors.lastname: De Carli
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Sofia
authors.initials: S
authors.lastname: Passera
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: Sirgiovanni
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Dessimone
authors.affiliation: Epidemiology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Consonni
authors.affiliation: Department of Obstetrics and Gynecology Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Acaia
authors.affiliation: Neonatal Intensive Care Unit, Istituto Giannina Gaslini Genova, Genoa, Italy.
authors.forename: Luca Antonio
authors.initials: LA
authors.lastname: Ramenghi
authors.affiliation: NICU, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Università degli Studi di Milano, Milan, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Mosca
mesh_terms: D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section / Q000706:statistics & numerical data*; D002823:Chorion / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007003:Hypoglycemia / Q000453:epidemiology*; D007223:Infant; D007226:Infant Mortality; D062071:Infant, Extremely Premature; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007558:Italy; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D059285:Pregnancy, Twin; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology*; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal