title: Short-term neonatal outcomes in diamniotic twin pregnancies delivered after 32 weeks and indications of late preterm deliveries.
abstract: OBJECTIVE
  We sought to compare neonatal outcomes in twin pregnancies following moderately preterm birth (MPTB), late preterm birth (LPTB), and term birth and determine the indications of LPTB.
  
  
  METHODS
  We performed a retrospective cohort study. MPTB was defined as delivery between 32(0/7) and 33(6/7) weeks and LPTB between 34(0/7) and 36(6/7) weeks. The composite neonatal adverse respiratory outcome was defined as respiratory distress syndrome and/or bronchopulmonary dysplasia. The composite neonatal adverse nonrespiratory outcome included early onset culture-proven sepsis, necrotizing enterocolitis, retinopathy of prematurity, intraventricular hemorrhage, or periventricular leukomalacia. LPTB cases were categorized as spontaneous (noniatrogenic), evidence-based iatrogenic, and non-evidence-based (NEB) iatrogenic.
  
  
  RESULTS
  Of the 747 twin deliveries during the study period, 453 sets met the inclusion criteria with 22.7% (n = 145) MPTB, 32.1% (n = 206) LPTB, and 15.9% (n = 102) term births. Compared with term neonates, the composite neonatal adverse respiratory outcome was increased following MPTB (relative risk [RR] 24; 95% confidence interval [CI] 3.0 to 193.6) and LPTB (RR 13.7; 95% CI 1.8 to 101.8). Compared with term neonates, the composite neonatal adverse nonrespiratory outcome was increased following MPTB (RR 22.3; 95% CI 3.9 to 127.8) and LPTB (RR 5.5; 95% CI 1.1 to 27.6). Spontaneous delivery of LPTB was 63.6% (n = 131/206) and the rate of iatrogenic delivery was 36.4% (n = 75/206). The majority, 66.6% (n = 50/75), of these iatrogenic deliveries were deemed NEB, giving a total of 24.2% (50/206) NEB deliveries in LPTB group.
  
  
  CONCLUSIONS
  Our data demonstrate a high rate of late preterm birth among twin pregnancies, with over half of nonspontaneous early deliveries due to NEB indications. Although our morbidity data will be helpful to providers in counseling patients, our finding of high NEB indications underscores the need for systematic evaluation of indications for delivery in LPTB twin deliveries. Furthermore, this may lead to more effective LPTB rate reduction efforts.
authors.affiliation: Department of Obstetrics and Gynecology, Baylor College of Medicine/Texas Children's Hospital, Houston, Texas.
authors.forename: Alireza A
authors.initials: AA
authors.lastname: Shamshirsaz
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Samadh F
authors.initials: SF
authors.lastname: Ravangard
authors.affiliation: Department of Preventive Medicine, USC Keck School of Medicine, Los Angeles, California.
authors.forename: Ali
authors.initials: A
authors.lastname: Ozhand
authors.affiliation: Department of Obstetrics and Gynecology, Baylor College of Medicine/Texas Children's Hospital, Houston, Texas.
authors.forename: Sina
authors.initials: S
authors.lastname: Haeri
authors.affiliation: Department of Obstetrics and Gynecology, The George Washington University School of Medicine, Washington, District of Columbia.
authors.forename: Amirhoushang A
authors.initials: AA
authors.lastname: Shamshirsaz
authors.affiliation: Department of Pediatrics, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Naveed
authors.initials: N
authors.lastname: Hussain
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Melissa
authors.initials: M
authors.lastname: Spiel
authors.affiliation: Department of Obstetrics and Gynecology, Waverly Women's Health Care, Columbia, South Carolina.
authors.forename: Oluseyi
authors.initials: O
authors.lastname: Ogunleye
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Rachel
authors.initials: R
authors.lastname: Billstrom
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Alison
authors.initials: A
authors.lastname: Sadowski
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Garry
authors.initials: G
authors.lastname: Turner
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Diane
authors.initials: D
authors.lastname: Timms
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: James F X
authors.initials: JF
authors.lastname: Egan
authors.affiliation: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Winston A
authors.initials: WA
authors.lastname: Campbell
mesh_terms: D000328:Adult; D001997:Bronchopulmonary Dysplasia / Q000453:epidemiology; D002543:Cerebral Hemorrhage / Q000453:epidemiology; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000706:statistics & numerical data; D020345:Enterocolitis, Necrotizing / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000453:epidemiology*; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D007969:Leukomalacia, Periventricular / Q000453:epidemiology; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000453:epidemiology*; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology; D012178:Retinopathy of Prematurity / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000453:epidemiology; D047929:Term Birth; D014427:Twins / Q000706:statistics & numerical data*; D055815:Young Adult