445: Maternal diet alters the offspring microbial gene catalogue as revealed by whole genome shotgun (WGS) sequencing in a primate model of obesity

catalogue as revealed by whole genome shotgun (WGS) sequencing in a primate model of obesity Radhika Ganu, Jun Ma, Antonio Frias, Diana Takahashi, Joseph Petrosino, Kevin Grove, James Versalovic, Kjersti Aagaard Baylor College of Medicine, Division of Maternal-Fetal Medicine, and Departments of Obstetrics and Gynecology, Molecular and Cell Biology, and the Bioinformatics Research Lab, Houston, TX, Oregon Health & Science University, Obstetrics and Gynecology, Portland, OR, Oregon Health & Science University, Oregon National Primate Research Center, Beaverton, OR, Baylor College of Medicine, Molecular Virology and Microbiology, Houston, TX, Baylor College of Medicine and Texas Children’s Hospital, Pathology & Immunology, Houston, TX OBJECTIVE: The infants microbiome (totality of microorganisms) is felt to be relatively sparse at birth. Based upon mode of delivery, gestational age, and breastfeeding it is thereafter variably populated. We have previously employed 16S-based metagenomics in our well-characterized primate model of maternal obesity, and observed that maternal diet additionally structures the offsprings microbiome. However, clear delineation of which species and microbial genes are influenced by the maternal diet has heretofor eluded us. Our study objective was to employ WGS metagenomics with metabolic pathway reconstruction to delineate not only which microbes are (or are not) present, but what these microbes are capable of doing. STUDY DESIGN: Age and weight-matched dams on control (13%) or HF (35%) diet yielded two distinct maternal cohorts emerged: obese HF diet sensitive [HFS] & lean HF resistant [HFR]. Based on the 16S-based analysis of over 200 comprehensive body site samples collected to date (placenta, oral, GI, fecal, GU) limited (n 12) samples for costly massively parallel WGS sequencing on the Illumina HiSeq (panel A). Binned microbial sequences were analyzed using MetaPhlAn (taxonomy abundance) and HuMAnN (pathway reconstruction). Significant features differentiating the groups were identified and ranked by Z-score corresponding to p-value. RESULTS: Consistent with maturation of the primate gut microbiome over the first year of life, maternal and juvenile gut microbiomes are distinguishable (Panel B). Juvenile gut microbiomes and associated metabolic pathways are significantly structured primarily by virtue of maternal diet, with a lesser contribution by maternal obesity (Panels C & D). CONCLUSION: High resolution metagenomics supports the notion that a highfat maternal diet in utero structures the offspring gut microbiome to 1 year of age; these are accompanied by significant alterations in bacterial metabolic gene catalogues. 446 Predictors of preterm delivery (PTD) after fetoscopic laser surgery (FLS) for twin twin transfusion syndrome (TTTS) Ramesha Papanna, Lovepreet Mann, Dana Block-Abraham, Irina Buhimschi, Michael Bebbington, Elisa Garcia, Nahla Khalek, Christopher Harman, Kenneth Moise Jr., Ahmet Baschat, Anthony Johnson Yale University, Ob/Gyn & Reprod. Sci., New Haven, CT, University of Maryland School of Medicine, Obstetrics, Gynecology and Reproductive Sciences, Baltimore, MD, University of Texas Health Science Center, Obstetrics, Gynecology and Reproductive Sciences, Houston, TX, The Children’s Hospital of Philadelphia, The Center for Fetal Diagnosis and Treatment, Philadelphia, PA OBJECTIVE: Despite the success of FLS for TTTS, PTD remains a critical contributor to adverse outcome. There is a paucity of data to explain the possible causes for PTD after FLS. Our objective is to identify the risk factors associated with preterm delivery after FLS. STUDY DESIGN: Prospectively collected data from 4 US fetal centers of 495 patients was centralized to an independent research center. Exclusion criteria were triplet pregnancies (n 24) and selective reduction for a failed FLS (n 12). Periand post-operative variables were collected and analyzed. Subgroups were created based on the median gestational age at delivery of 32 weeks (mean SD: 31.2 4.9w). Risk factors and outcomes were compared between these groups. Comparative statistics were performed using appropriate statistical analysis (statistical significance p 0.05). Multivariate logistic regression was performed on the significant factors on univariate analysis. RESULTS: Significant comparisons are shown in Table 1. There were no differences in peri-operative variables. On multivariate analysis, greater maternal age at procedure, iPPROM (occurring in 32%).and larger cannula diameter increased the risk for early PTD. iPPROM reduced the procedure to delivery interval by 22 days (Kaplan-Meier survival analysis; p 0.001) and the associated rate for 9,10 and 12 Fr cannulas were 16%, 30%,42%, respectively, and procedure-to-delivery intervals (days) were 83.4 34.6, 79.3 36, and 59.6 36.8, respectively (all 0.001). Pre-viable ( 24 weeks) delivery occurred in 10%, and was attributable to iPPROM in 30% and spontaneous preterm labor in 57%. CONCLUSION: Early preterm delivery remains a major complication of FLS. Cannulas size and the associated rate of iPPROM appear to be the significant contributors to preterm birth. Further research should focus on methods to prevent iPPROM and to improve instrumentation to decrease the size of the cannula and maintain better visualization during fetoscopy. Poster Session III Doppler Assess, Fetus, Prematurity, U/S, Med-Surg-Diseases www.AJOG.org