60: Timing of delivery in twin pregnancies according to chorionicity

Fetus

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Oral Concurrent Session 5

weeks= gestation with certain chorionicity, was examined to establish the better gestational age to deliver twins on an outcome-based methodology. DiDi-fused placenta twins (82 cases) were excluded. Adverse neonatal outcome was defined as perinatal mortality or occurrence of major morbidities. RESULTS: Gestational age at delivery in Monochorionic twins (n⫽122, 31.4%) was lower than in dichorionic twins, regardless of outcomes. Altogether, twins with adverse outcome had lower gestational age at delivery than twins with good outcomes (35.9 vs 36.8 weeks, p ⬍0.001). Kaplan Meier survival function was used to establish the trends of survival without adverse outcomes in relation to the gestational age on the basis of chorionicity (Figure). The analysis shows an increase of adverse outcome after 36 weeks= gestation for monochorionic twins and after 38 weeks= gestation for dichorionic twins. CONCLUSION: The optimal gestational age to deliver twins is different based on chorionicity. After 36 weeks= gestation, there is an increase of adverse perinatal outcomes in monochorionic pregnancies, while this occurs two weeks later in dichorionic twins.

0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.073

59 Programmed dysfunction of neuronal stem cells in low birthweight newborns Mina Desai1, Tie Li1, Stanislav Karsten1, Michael G. Ross1 1

LABioMed at Harbor-UCLA Med. Ctr., Dept. of Ob/Gyn, Torrance, California

OBJECTIVE: Low birthweight (LBW) offspring have reduced anorexi-

genic responses that may contribute to hyperphagia and adult obesity. The anorexigenic hormone leptin is a prenatal neurotrophic factor that promotes brain growth and development. As leptin levels are reduced in LBW fetuses and newborns, we hypothesized that reduced neurotrophic stimulation during critical periods may impair neurodevelopment. We utilized neuronal stem cells (NSC) to investigate the growth and differentiation of hypothalamic neuronal cells, in response to leptin. STUDY DESIGN: Control dams received ad libitum food whereas study dams were 50% food-restricted from pregnancy day 10 to 21 to produce LBW-leptin deficient newborns. At day 1 of age, hypothalamic NSC were cultured in complete (CM) or differentiating medium (DM) for basal studies. For neurotrophic stimulation studies, NSC were treated with leptin (10, 20, 40 ng/ml). Proliferation rate was measured by MTT assay and differentiation responses by expression (Western Blot) of neuronal (Tuj1) or astrocyte (GFAP) markers. RESULTS: The basal proliferation index was significantly reduced in NSC from LBW newborns (15%). Although LBW and Control NSC responded to leptin with dose-dependent increments in proliferation, LBW NSC displayed reduced proliferation at all doses as compared to Controls (50-60%). Further, LBW NSC had reduced basal differentiation to both neuronal (Tuj1, 22%) and astrocyte (GFAP, 42%) cell lines, as compared to Controls. In response to leptin, both LBW and Controls showed dose-dependent increments in differentiation though at all times, the LBW exhibited reduced neuronal (⬃34%) and astrocyte (⬃29%) differentiation as compared to Controls. CONCLUSION: LBW newborns have programmed dysfunctional hypothalamic NSC, evident by reduced basal and stimulated proliferation and neuronal/astrocyte differentiation. This may contribute towards reduced neuronal development pathways in LBW offspring, and the resultant neurologic and behavioral abnormalities. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.074

60 Timing of delivery in twin pregnancies according to chorionicity Ilaria Follesa1, Patrizia Vergani1, Sabrina Cozzolino1, Francesca Maria Russo1, Tiziana Fedeli2, Luisa Ventura2 1

University of Milano-Bicocca, Obstetrics and Gynecology, Monza, Milan, Italy, 2University of Milano-Bicocca, Neonatology, Monza, Milan, Italy

OBJECTIVE: To identify the best time to deliver twins in relation to chorionicity and adverse outcomes. STUDY DESIGN: A cohort of 389 twin pregnancies, followed with a consistent protocol between 1994 and 2008and delivered at ⬎34.0

0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.075

61 Maternal undernutrition induces fetal growth restriction by PPAR-mediated placental apoptosis Louiza Belkacemi1, Quinghai Liu1, Mina Desai1, Michael G. Ross1 1

LABioMed at Harbor-UCLA Med. Ctr., Dept. of Ob/Gyn, Torrance, California

OBJECTIVE: Maternal undernutrition (MUN) during pregnancy re-

sults in growth restricted (IUGR) fetuses, in part a result of insufficient maternal nutrient supply. In addition, cell death (apoptosis) within the placenta may reduce the capacity for nutrient/oxygen transfer. We sought to determine if MUN induced placental apoptosis, and whether this may be mediated via dysregulation of pro (cytochrome) and anti (PPAR, Bc12) apoptotic factors. We analyzed the apoptotic index and protein expression of apoptotic mediators in the two placental positions with optimal and reduced nutrient/oxygen supply (proximal, mid-horn), and the placental zones associated with hormone production or feto-maternal exchange (basal, labyrinth). STUDY DESIGN: Pregnant rats were fed an AdLib diet or were 50% MUN starting at E10. At E20, left mid- and proximal horn apoptosis was measured with TUNEL assay. The corresponding right placentas were separated into basal and labyrinth zones and analyzed for PPAR, Bcl2 (anti-apoptotic protein) and cytochrome c (initiator of apoptotic process) expression. RESULTS: At E20, MUN maternal, fetal and placental (basal and labyrinth zones) weights were significantly decreased. MUN proximal placentas had markedly increased apoptosis in basal (3.3⫾1.0 vs 0.3⫾0.1%) and labyrinth (8.6⫾1.4 vs 0.6⫾0.3%) zones as compared

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