normal labor and delivery正常分娩

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1、NormalLaborandDeliveryMrs.MahdiaSamahaKonyDefinitionLaboristheprocessbywhichcontractionsofthegraviduterusexpelthefetus.Atermpregnancydeliversbetween37and42weeksfromthelastmenstrualperiod(LMP).Pretermlaboristhatoccurringbefore37weeksofgestationalage.Postdatepregnancyoccurs

2、after42weeksgestationandrequirescarefulmonitoring.Terminationofpregnancybefore20weeksofgestationisdefinedaseitherspontaneousorelectiveabortion.DefinitionPrimigravida-pregnantforfirsttimeMultigravida-pregnantmorethanonceViability-abletosurviveoutsidethewomb(24+weeksgestati

3、on)Nulliparous-nevercarriedapregnancytoviabilityMultiparous-hashadtwoormoredeliveriesthatwerecarriedtoviabilityTheinitiationoflaborLaborisinfluencedbycombinationoffactorsinclude:-Uterinestretching-Progesteronewithdrawal-increasedoxytocinsensitivity-increasedlevelofprostag

4、landinsTheoriesthatexplaininitiationoflabor:Changeinestrogen-to-progesteroneratio.Whichfacilitatecoordinationofuterinecontractionandmyometriumstretching.Prostaglandinlevelincreaseinlatepregnancysecondarytoelevatedlevelofestrogen.Itstimulatessmoothmusclecontractionoftheute

5、rus:LeadstomyometriumcontractionReducecervicalresistanceThecervixbecomessoft,thinoutanddilateduringlabor.Theoriesthatexplaininitiationoflabor:Increasednumberofoxytocinreceptorslateinpregnancy,thisincreasedthesensitivitytooxytocinasitsalsoincreasedinresponsetoestrogenrisin

6、g.Oxytocinalsoaidinstimulationofprostaglandinsynthesisinthedecidua.OxytocineffectThehormoneoxytocinstimulatesandenhanceslaborcontractions.Asthebabymovestowardthevagina(birthcanal),pressurereceptorswithinthecervix(muscularoutletofuterus)sendmessagestothebraintoproduceoxyto

7、cin.Oxytocintravelstotheuterusthroughthebloodstream,stimulatingthemusclesintheuterinewalltocontractstronger(increaseofidealnormalvalue).Thecontractionsintensifyincreaseuntilthebabyisoutsidethebirthcanal.Whenthestimulustothepressurereceptorsends,oxytocinproductionstopsandl

8、aborcontractionscease.PremonitorysignsoflaborCervicalchangessofteninganddilationwithdescentofthe