Mice, Inbred C57BLMice, Inbred C3HAnimals, Outbred StrainsPregnancyPregnancy, AnimalGestational AgeFetusLitter SizeReproductionLabor, ObstetricPlacentaMaternal-Fetal ExchangeSpecies SpecificitySwineUltrasonography, PrenatalPregnancy Trimester, SecondPregnancy Trimester, FirstInfant, NewbornPregnancy Trimester, ThirdFetal DevelopmentFetal DiseasesEmbryonic and Fetal DevelopmentPregnancy OutcomeBirth WeightInfant, PrematureFetal DeathPregnancy ComplicationsLactationFetal WeightPrenatal Exposure Delayed EffectsUterusAmniotic FluidPremature BirthFetal HeartPregnancy, MultipleObstetric Labor, PrematureFetal Growth RetardationMaternal Nutritional Physiological PhenomenaAnimals, NewbornCrown-Rump LengthHeart Rate, FetalTwinsPlacental CirculationBody WeightParityPrenatal DiagnosisFetal BloodPregnancy TrimestersPrenatal Nutritional Physiological PhenomenaCesarean SectionPre-EclampsiaOrgan SizeMaternal ExposureTrophoblastsFetal Organ Maturity