Embryo TransferUterusSingle Embryo TransferFertilization in VitroEmbryo ImplantationPregnancy RatePregnancyEmbryo, MammalianCryopreservationPregnancy, MultipleSperm Injections, IntracytoplasmicPregnancy OutcomeBlastocystInfertility, FemaleLive BirthInfertilityEmbryo, NonmammalianOvulation InductionBack PainCleavage Stage, OvumChick EmbryoLow Back PainTwinsZygote Intrafallopian TransferOocyte DonationReproductive Techniques, AssistedEmbryonic DevelopmentReproductive TechniquesEmbryonic and Fetal DevelopmentBackAbortion, SpontaneousEndometriumWomenWomen's HealthBlastomeresOocytesChorionic GonadotropinEmbryo Culture TechniquesBirth RateProgesteronePreimplantation DiagnosisMorulaTime FactorsPregnancy, AnimalOvarian Hyperstimulation SyndromeUterine ContractionEmbryo LossGene Transfer TechniquesMenotropinsEstradiolVitrificationCervix UteriFallopian Tube DiseasesRetrospective StudiesCloning, OrganismPregnancy, EctopicMaternal AgeSuperovulationOocyte RetrievalInsemination, ArtificialFallopian TubesNuclear Transfer TechniquesFertilizationUltrasonographyLuteal PhaseMyometriumZona PellucidaOvaryPregnancy Reduction, MultifetalBuserelinCulture TechniquesCatheterizationGene Transfer, HorizontalFollicle Stimulating HormonePregnancy, TwinZygoteGene Expression Regulation, DevelopmentalMultiple Birth OffspringFreezingPregnancy, TubalFertility Agents, FemaleVaginaSpermatozoaSurrogate MothersTwinning, MonozygoticTreatment OutcomePregnancy MaintenanceLabor Stage, FirstCattleIncubatorsLitter SizeTripletsGonadotropin-Releasing HormoneProspective StudiesMicroinjectionsChorionic Gonadotropin, beta Subunit, HumanAbortion, VeterinaryFollicular FluidNafarelinPseudopregnancy