PlacentaTwinsDiseases in TwinsPregnancyTwins, MonozygoticTwins, ConjoinedTwins, DizygoticPregnancy OutcomePregnancy ComplicationsPregnancy, AnimalPlacenta DiseasesPregnancy, TwinPregnancy, EctopicPregnancy Trimester, FirstPregnancy, MultiplePregnancy Trimester, ThirdPlacenta PreviaTwin Studies as TopicPlacenta AccretaPlacenta, RetainedPregnancy RatePregnancy TrimestersPregnancy ProteinsTrophoblastsPregnancy Trimester, SecondPregnancy Complications, CardiovascularGestational AgePregnancy TestsPregnancy in DiabeticsMaternal-Fetal ExchangePregnancy, TubalPregnancy Complications, InfectiousPregnancy Complications, NeoplasticPre-EclampsiaPregnancy in AdolescenceFetal DeathInfant, NewbornChorionic VilliAbortion, SpontaneousPregnancy, High-RiskPlacentationFetusUterusUltrasonography, PrenatalPregnancy, UnplannedPregnancy, UnwantedFetal Growth RetardationPregnancy Complications, HematologicPregnancy Complications, ParasiticChorionBirth WeightCesarean SectionPregnancy, ProlongedFetal DevelopmentDeciduaPregnancy, AbdominalAbortion, InducedEmbryo ImplantationPregnancy Reduction, MultifetalEmbryo TransferFertilization in VitroPregnancy MaintenanceFetofetal TransfusionLabor, ObstetricParityTripletsPlacental CirculationObstetric Labor, PrematureMaternal AgePrenatal Exposure Delayed EffectsPremature BirthPrenatal CareAmniotic FluidExtraembryonic MembranesDelivery, ObstetricProgesteroneHypertension, Pregnancy-InducedPlacental LactogenHydatidiform MoleFetal DiseasesCongenital AbnormalitiesPrenatal DiagnosisChorionic GonadotropinRisk FactorsMaternal ExposureLactationDiabetes, GestationalEndometriumReproductive Techniques, AssistedInfertility, FemaleAbnormalities, Drug-InducedCohort StudiesFetal BloodSperm Injections, IntracytoplasmicAbortion, TherapeuticInfant, Low Birth WeightAmnionUterine HemorrhageChoriocarcinomaAbortion, Veterinary