Multiple Birth OffspringPregnancy, MultipleTripletsPregnancyReproductive Techniques, AssistedTwinsPregnancy Reduction, MultifetalPregnancy OutcomeBirth RateEmbryo TransferGestational AgeInfant, NewbornMaternal AgeFertilization in VitroBirth WeightQuadrupletsReproductive TechniquesInfertilitySingle Embryo TransferPregnancy ComplicationsPremature BirthAbortion, SpontaneousInfant, Low Birth WeightOocyte DonationObstetric Labor, PrematureTwins, MonozygoticPregnancy RateInfant, PrematurePregnancy Trimester, FirstInfant MortalityFetal DeathUltrasonography, PrenatalOvulation InductionBirth OrderPregnancy Trimester, SecondCongenital AbnormalitiesRisk FactorsPrenatal Exposure Delayed EffectsBirth CertificatesPerinatal CareRetrospective StudiesDelivery, ObstetricLive BirthFetusPregnancy, Animal