Mono-Di twins, chronic hypertension and diabetes were similar in allthree groups. The rate of composite neonatal outcome was progres-sively higher in those twins with MPTB and LPTB compared withterm births (MPTB 52.0% versus LPTB 22.3% versus TB 2.9%, p �0.001). All the short term neonatal outcomes are shown in Table 1.CONCLUSION: Twin pregnancies born moderately and late preterm en-counter higher rates of neonatal morbidities compared with twinsborn at term.

Table 1. Neonatal Outcomes (n�number of neonates)

MPTB (n�290) LPTB (n�412) TB (n�204) p-value

RDS, n (%) 50 (17.2) 33 (8) 0 (0) �0.0001..........................................................................................................................................................................................

Early Sepsis, n (%) 22 (7.5) 13 (13.1) 1 (0.4) �0.0001..........................................................................................................................................................................................

NEC, n (%) 2 (0.6) 3 (0.7) 0 (0) �0.0037..........................................................................................................................................................................................

BPD, n (%) 7 (2.4) 5 (1.2) 0 (0) �0.0001..........................................................................................................................................................................................

ROP, n (%) 3 (1) 0 (0) 0 (0) �0.0001..........................................................................................................................................................................................

IVH, n (%).................................................................................................................................................................................

I&II 3 (1) 0 (0) 0 (0) �0.0001.................................................................................................................................................................................

III &IV 3 (1) 0 (0) 0 (0) �0.0001..........................................................................................................................................................................................

APGAR 5-minutes �7,n (%)

8 (2.7) 7 (1.7) 1 (0.4) �0.0001

..........................................................................................................................................................................................

MV, n (%) 55 (18.9) 31 (7.5) 1 (2) �0.0001..........................................................................................................................................................................................

CPAP, n (%) 109 (37.7) 81 (19.6) 5 (2.4) �0.0001..........................................................................................................................................................................................

NICU admission, n (%) 285 (98.2) 262 (63.6) 17 (8.3) �0.0001..........................................................................................................................................................................................

Median Length ofNICU, (range)

20 (4-101) 13 (1-56) 5 (2-113) �0.0001

..........................................................................................................................................................................................

455 Late preterm birth in twin pregnancies:deliveries indications and neonatal outcomesAlireza A. Shamshirsaz1, Samadh Ravangard1, Ozhand Ali2,Naveed Hussain3, James Egan1, Amirhoushang A. Shamshirsaz4,Rachel Bilstrom1, Allison Sadowski1, Diane Timms1, OluseyiOgunleye5, Leah Mitchell1, Kevin Lenehan1, Gary Turner1,Padmalatha Gurram1, Kisti Fuller1, Winston Campbell11University of Connecticut. Health Center, Obstetrics and Gynecology,farmington, CT, 2USC Keck School of Medicine, Department of PreventiveMedicine, Los Angeles, CA, 3University of Conn. Health Center, Pediatrics,Farmington, CT, 4St. Francis Hospital, Obstetrics and Gynecology, Hartford, CT,5Waverly Women’s Health Care, Obstetrics and Gynecology, Columbia, SCOBJECTIVE: Due to the evolving controversy regarding late pretermbirth (AJOG. 2011; 20(6): 459-60), we evaluated the indications forlate preterm twin birth (LPTB) (34 0/7-36 6/7 weeks) and comparedthe short term composite neonatal morbidity and mortality (M/M)outcomes of LPTB to term twin births ( �37 weeks).STUDY DESIGN: We retrospectively developed a Twin PregnancyPerinatal Database (TPPD) at our University Hospital for deliveriesbetween January 1, 1991 and January 1, 2011. Cases with major mal-formation, monoamniotic-monochorionic twins, monochorionic-diamniotic twins with twin to twin transfusion syndrome, alloimmu-nization, and fetal demise were excluded (8.5%, 66 pregnancies). Wedefined short term composite neonatal M/M as one or more of thefollowing prior to discharge: neonatal death, respiratory distress syn-drome, early onset culture-proven sepsis (sepsis), necrotizing entero-colitis, bronchopulmonary dysplasia, grade 3 or 4 intraventricularhemorrhage and severe retinopathy of prematurity.RESULTS: There were a total of 747 twin pregnancies in TPPD, 206(37.1%) were in LPTB and 102 (20.9%) were term. The mean (SD)gestational weeks at delivery for LPTB and term twin were 35.20.3 and37.70.2 respectively. Indications for delivery in the LPTB are shown intable 1. Short term composite neonatal M/M in term twins (0.5%) wassignificantly lower compared to LPTB (13.1%) (p�0.001).CONCLUSION: Late preterm twin births show higher rates of compositeneonatal morbidity and mortality compared to term twins. While the

majority of LPTB were for accepted obstetrical indications, about 6%of cases did not have a clear indication. Further strategies to lower latepreterm births in twins need to focus on these indications.

Table 1. Indications for Late preterm birth in twin pregnancies

IndicationLate pretermtwin births (%)

Spontaneous preterm labor 33.6..........................................................................................................................................................................................

Preterm premature rupture of membranes (PPROM) 19.8..........................................................................................................................................................................................

Spontaneous preterm labor/PPROM 10.3..........................................................................................................................................................................................

Mild preeclampsia/gestational hypertension 10.3..........................................................................................................................................................................................

Severe preeclampsia/HELLP syndrome 7.3..........................................................................................................................................................................................

Intrauterine growth restriction (IUGR)/oligohydraminos 6.4..........................................................................................................................................................................................

Non-reassuring fetal status 4.4..........................................................................................................................................................................................

Other indications 2.2..........................................................................................................................................................................................

No clear indication 5.7..........................................................................................................................................................................................

456 The effect of magnesium sulfate administrationfor neuroprotection on latency in women withpreterm premature rupture of membranesAmanda Horton1

1For the Eunice Kennedy Shriver National Institute of Child Health and HumanDevelopment MFMU Network, Maternal Fetal Medicine, Bethesda, MDOBJECTIVE: To determine if magnesium sulfate infusion for neuropro-tection increases latency in women with preterm premature ruptureof membranes between 24 and 31 6/7 weeks’ gestation.STUDY DESIGN: This is a secondary analysis of a randomized controlledtrial of magnesium sulfate for prevention of cerebral palsy. Gravidwomen between 24 and 31 6/7 weeks’ gestation with preterm prematurerupture of membranes (pPROM) without evidence of preterm laborwere randomized to receive magnesium sulfate, administered intrave-nously as a 6-g bolus followed by a constant infusion of 2 g per hour for 12hours if undelivered, or placebo. Latency outcomes for this analysis weredelivery within 48 hours and 7 days from randomization. Neonatal out-comes included a composite of RDS, IVH grades 3 or 4, sepsis, necrotiz-ing enterocolitis, retinopathy of prematurity, or death.RESULTS: A total of 1377 women were included. The rate of deliverywithin the first 48 hours was not different in the magnesium sulfateand the placebo groups (9.0% and 9.3%, p�0.85). Latency � 7 dayswas similar between groups (46.3% and 42.6%, p�0.17). Median la-tency was also similar between groups (median [interquartile range] 7days [3-15] and 8 days [3-18], p �0.13). Neonatal outcomes did notdiffer between groups after adjustment for twin gestation. (Table).CONCLUSION: Magnesium sulfate administration for neuroprotection inwomen with preterm premature rupture of membranes before 32 weeksdoes not increase latency at 48 hours or 7 days nor does it impact latency.

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