Birth - Wikipedia

Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is ... Birth FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Processofbearingoffspring Thisarticleisaboutbirthinmammalsandotheranimals.Forbirthinhumans,seeChildbirth.Forotheruses,seeBirth(disambiguation). "Parturition"redirectshere.FortheStarTrekepisode,seeParturition(StarTrek:Voyager). Lambing:themotherlicksthefirstlambwhilegivingbirthtothesecond Birthistheactorprocessofbearingorbringingforthoffspring,[1]alsoreferredtointechnicalcontextsasparturition.Inmammals,theprocessisinitiatedbyhormoneswhichcausethemuscularwallsoftheuterustocontract,expellingthefetusatadevelopmentalstagewhenitisreadytofeedandbreathe. Insomespeciestheoffspringisprecocialandcanmovearoundalmostimmediatelyafterbirthbutinothersitisaltricialandcompletelydependentonparenting. Inmarsupials,thefetusisbornataveryimmaturestageafterashortgestationalperiodanddevelopsfurtherinitsmother'swomb'spouch. Itisnotonlymammalsthatgivebirth.Somereptiles,amphibians,fishandinvertebratescarrytheirdevelopingyounginsidethem.Someoftheseareovoviviparous,withtheeggsbeinghatchedinsidethemother'sbody,andothersareviviparous,withtheembryodevelopinginsideherbody,asinthecaseofmammals. Contents 1Mammals 1.1Humanchildbirth 1.2Cattle 1.3Dogs 1.4Marsupials 2Otheranimals 3Seealso 4References 5Citedtexts Mammals[edit] Largemammals,suchasprimates,cattle,horses,someantelopes,giraffes,hippopotamuses,rhinoceroses,elephants,seals,whales,dolphins,andporpoises,generallyarepregnantwithoneoffspringatatime,althoughtheymayhavetwinormultiplebirthsonoccasion. Intheselargeanimals,thebirthprocessissimilartothatofahuman,thoughinmosttheoffspringisprecocial.Thismeansthatitisborninamoreadvancedstatethanahumanbabyandisabletostand,walkandrun(orswiminthecaseofanaquaticmammal)shortlyafterbirth.[2] Inthecaseofwhales,dolphinsandporpoises,thesinglecalfisnormallyborntailfirstwhichminimizestheriskofdrowning.[3]Themotherencouragesthenewborncalftorisetothesurfaceofthewatertobreathe.[4] Mostsmallermammalshavemultiplebirths,producinglittersofyoungwhichmaynumbertwelveormore.Intheseanimals,eachfetusissurroundedbyitsownamnioticsacandhasaseparateplacenta.Thisseparatesfromthewalloftheuterusduringlaborandthefetusworksitswaytowardsthebirthcanal.[citationneeded] Largemammalswhichgivebirthtotwinsismuchmorerare,butitdoesoccuroccasionallyevenformammalsaslargeaselephants.InApril2018,approximately8-montholdelephanttwinsweresightedjoiningtheirmother'sherdintheTarangireNationalParkofTanzania,estimatedtohavebeenborninAugust2017.[5] Humanchildbirth[edit] Mainarticle:Childbirth Furtherinformation:Adaptationtoextrauterinelife Anillustrationofnormalhead-firstpresentationbytheobstetricianWilliamSmelliefromabout1792.Themembraneshaverupturedandthecervixisfullydilated. Humansusuallyproduceasingleoffspringatatime.Themother'sbodyispreparedforbirthbyhormonesproducedbythepituitarygland,theovaryandtheplacenta.[2]Thetotalgestationperiodfromfertilizationtobirthisnormallyabout38weeks(birthusuallyoccurring40weeksafterthelastmenstrualperiod).Thenormalprocessofchildbirthtakesseveralhoursandhasthreestages.Thefirststagestartswithaseriesofinvoluntarycontractionsofthemuscularwallsoftheuterusandgradualdilationofthecervix.Theactivephaseofthefirststagestartswhenthecervixisdilatedmorethanabout4 cmindiameterandiswhenthecontractionsbecomestrongerandregular.Thehead(orthebuttocksinabreechbirth)ofthebabyispushedagainstthecervix,whichgraduallydilatesuntilisfullydilatedat10 cmdiameter.Atsometime,theamnioticsacburstsandtheamnioticfluidescapes(alsoknownasruptureofmembranesorbreakingthewater).[6]Instagetwo,startingwhenthecervixisfullydilated,strongcontractionsoftheuterusandactivepushingbythemotherexpelsthebabyoutthroughthevagina,whichduringthisstageoflabouriscalledabirthcanalasthispassagecontainsababy,andthebabyisbornwithumbilicalcordattached.[7]Instagethree,whichbeginsafterthebirthofthebaby,furthercontractionsexpeltheplacenta,amnioticsac,andtheremainingportionoftheumbilicalcordusuallywithinafewminutes.[8] Enormouschangestakeplaceinthenewborn'scirculationtoenablebreathinginair.Intheuterus,theunbornbabyisdependentoncirculationofbloodthroughtheplacentaforsustenanceincludinggaseousexchangeandtheunbornbaby'sbloodbypassesthelungsbyflowingthroughtheforamenovale,whichisaholeintheseptumdividingtherightatriumandleftatrium.Afterbirththeumbilicalcordisclampedandcut,thebabystartstobreatheair,andbloodfromtherightventriclestartstoflowtothelungsforgaseousexchangeandoxygenatedbloodreturnstotheleftatrium,whichispumpedintotheleftventricle,andthenpumpedintothemainarterialsystem.Asaresultofthesechanges,thebloodpressureintheleftatriumexceedsthepressureintherightatrium,andthispressuredifferenceforcestheforamenovaletocloseseparatingtheleftandrightsidesoftheheart.Theumbilicalvein,umbilicalarteries,ductusvenosusandductusarteriosusarenotneededforlifeinairandintimethesevesselsbecomeligaments(embryonicremnants).[9] Cattle[edit] Acowgivingbirth Birthingincattleistypicalofalargermammal.Acowgoesthroughthreestagesoflaborduringnormaldeliveryofacalf.Duringstageone,theanimalseeksaquietplaceawayfromtherestoftheherd.Hormonechangescausesofttissuesofthebirthcanaltorelaxasthemother'sbodypreparesforbirth.Thecontractionsoftheuterusarenotobviousexternally,butthecowmayberestless.Shemayappearagitated,alternatingbetweenstandingandlyingdown,withhertailslightlyraisedandherbackarched.Thefetusispushedtowardthebirthcanalbyeachcontractionandthecow'scervixgraduallybeginstodilate.Stageonemaylastseveralhours,andendswhenthecervixisfullydilated.Stagetwocanbeseentobeunderwaywhenthereisexternalprotrusionoftheamnioticsacthroughthevulva,closelyfollowedbytheappearanceofthecalf'sfronthoovesandheadinafrontpresentation(oroccasionallythecalf'stailandrearendinaposteriorpresentation).[10]Duringthesecondstage,thecowwillusuallyliedownonhersidetopushandthecalfprogressesthroughthebirthcanal.Thecompletedeliveryofthecalf(orcalvesinamultiplebirth)signifiestheendofstagetwo.Thecowscramblestoherfeet(iflyingdownatthisstage),turnsroundandstartsvigorouslylickingthecalf.Thecalftakesitsfirstfewbreathsandwithinminutesisstrugglingtorisetoitsfeet.Thethirdandfinalstageoflaboristhedeliveryoftheplacenta,whichisusuallyexpelledwithinafewhoursandisofteneatenbythenormallyherbivorouscow.[10][11] Dogs[edit] Furtherinformation:Caninereproduction§ Gestationandlitters Birthistermedwhelpingindogs.[12]Amongdogs,aswhelpingapproaches,contractionsbecomemorefrequent.Labourinthebitchcanbedividedinto3stages.Thefirststageiswhenthecervixdilates,thiscausesdiscomfortandrestlessnessinthebitch.Commonsignsofthisstagearepanting,fasting,and/orvomiting.Thismaylastupto12hrs.[12]Stagetwoisthepassageoftheoffspring.[12]Theamnioticsaclookinglikeaglisteninggreyballoon,withapuppyinside,ispropelledthroughthevulva.Afterfurthercontractions,thesacisexpelledandthebitchbreaksthemembranesreleasingclearfluidandexposingthepuppy.Themotherchewsattheumbilicalcordandlicksthepuppyvigorously,whichstimulatesittobreathe.Ifthepuppyhasnottakenitsfirstbreathwithinaboutsixminutes,itislikelytodie.Furtherpuppiesfollowinasimilarwayonebyoneusuallywithlessstrainingthanthefirstusuallyat15-60minintervals.Ifapuphasnotbeenpassedin2hrsaveterinarianshouldbecontacted.[12]Stagethreeisthepassingoftheplacentas.Thisoftenoccursinconjunctionwithstagetwowiththepassingofeachoffspring.[12]Themotherwillthenusuallyeattheafterbirth.[13]Thisisanadaptiontokeepthedencleanandpreventitsdetectionbypredators.[12] Marsupials[edit] Seealso:Marsupial§ Reproductivesystem,andMarsupial§ Earlydevelopment Akangaroojoeyfirmlyattachedtoanippleinsidethepouch Aninfantmarsupialisborninaveryimmaturestate.[14]Thegestationperiodisusuallyshorterthantheintervalsbetweenoestrusperiods.Thefirstsignthatabirthisimminentisthemothercleaningoutherpouch.Whenitisborn,theinfantispink,blind,furlessandafewcentimetreslong.Ithasnostrilsinordertobreatheandforelegstoclingontoitsmother'shairsbutitshindlegsareundeveloped.Itcrawlsthroughitsmother'sfurandmakesitswayintothepouch.Hereitfixesontoateatwhichswellsinsideitsmouth.Itstaysattachedtotheteatforseveralmonthsuntilitissufficientlydevelopedtoemerge.[15]Joeysarebornwith"oralshields";inspecieswithoutpouchesorwithrudimentarypouchesthesearemoredevelopedthaninformswithwell-developedpouches,implyingaroleinmaintainingtheyoungattachedtothemother'snipple.[16] Otheranimals[edit] ACladoceragivingbirth(100xmagnification) Manyreptilesandthevastmajorityofinvertebrates,mostfish,amphibiansandallbirdsareoviparous,thatis,theylayeggswithlittleornoembryonicdevelopmenttakingplacewithinthemother.Inaquaticorganisms,fertilizationisnearlyalwaysexternalwithspermandeggsbeingliberatedintothewater(anexceptionissharksandrays,whichhaveinternalfertilization[17]).Millionsofeggsmaybeproducedwithnofurtherparentalinvolvement,intheexpectationthatasmallnumbermaysurvivetobecomematureindividuals.Terrestrialinvertebratesmayalsoproducelargenumbersofeggs,afewofwhichmayavoidpredationandcarryonthespecies.Somefish,reptiles,andamphibianshaveadoptedadifferentstrategyandinvesttheireffortinproducingasmallnumberofyoungatamoreadvancedstagewhicharemorelikelytosurvivetoadulthood.Birdscarefortheiryounginthenestandprovidefortheirneedsafterhatchinganditisperhapsunsurprisingthatinternaldevelopmentdoesnotoccurinbirds,giventheirneedtofly.[18] Ovoviviparityisamodeofreproductioninwhichembryosdevelopinsideeggsthatremaininthemother'sbodyuntiltheyarereadytohatch.Ovoviviparousanimalsaresimilartoviviparousspeciesinthatthereisinternalfertilizationandtheyoungareborninanadvancedstate,butdifferinthatthereisnoplacentalconnectionandtheunbornyoungarenourishedbyeggyolk.Themother'sbodyprovidesgasexchange(respiration),butthatislargelynecessaryforoviparousanimalsaswell.[18]Inmanysharkstheeggshatchintheoviductwithinthemother'sbodyandtheembryosarenourishedbytheegg'syolkandfluidssecretedbyglandsinthewallsoftheoviduct.[19]TheLamniformesharkspracticeoophagy,wherethefirstembryostohatchconsumetheremainingeggsandsandtigersharkpupscannibalisticallyconsumeneighbouringembryos.Therequiemsharksmaintainaplacentallinktothedevelopingyoung,thispracticeisknownasviviparity.Thisismoreanalogoustomammaliangestationthantothatofotherfishes.Inallthesecases,theyoungarebornaliveandfullyfunctional.[20]Themajorityofcaeciliansareovoviviparousandgivebirthtoalreadydevelopedoffspring.Whentheyounghavefinishedtheiryolksacstheyfeedonnutrientssecretedbycellsliningtheoviductandeventhecellsthemselveswhichtheyeatwithspecialistscrapingteeth.[21]TheAlpinesalamander(Salamandraatra)andseveralspeciesofTanzaniantoadinthegenusNectophrynoidesareovoviviparous,developingthroughthelarvalstageinsidethemother'soviductandeventuallyemergingasfullyformedjuveniles.[22] Amoredevelopedformofviviparitycalledplacentalviviparityisadoptedbysomespeciesofscorpions[23]andcockroaches,[24]certaingeneraofsharks,snakesandvelvetworms.Inthese,thedevelopingembryoisnourishedbysomeformofplacentalstructure.Theearliestknownplacentawasfoundrecentlyinagroupofextinctfishescalledplacoderms.AfossilfromAustralia'sGogoFormation,laiddownintheDevonianperiod,380 millionyearsago,wasfoundwithanembryoinsideitconnectedbyanumbilicalcordtoayolksac.Thefindconfirmedthehypothesisthatasub-groupofplacoderms,calledptyctodontids,fertilizedtheireggsinternally.Somefishesthatfertilizetheireggsinternallyalsogivebirthtoliveyoung,asseenhere.Thisdiscoverymovedourknowledgeoflivebirthback200 millionyears.[25]Thefossilofanothergenuswasfoundwiththreeembryosinthesameposition.[26]Placodermsareasistergroupoftheancestorofalllivingjawedfishes(Gnathostomata),includingbothchondrichthyians,thesharks&rays,andOsteichthyes,thebonyfishes. Amonglizards,theviviparouslizardZootocavivipara,slowwormsandmanyspeciesofskinkareviviparous,givingbirthtoliveyoung.SomeareovoviviparousbutotherssuchasmembersofthegeneraTiliquaandCorucia,givebirthtoliveyoungthatdevelopinternally,derivingtheirnourishmentfromamammal-likeplacentaattachedtotheinsideofthemother'suterus.Inarecentlydescribedexample,anAfricanspecies,Trachylepisivensi,hasdevelopedapurelyreptilianplacentadirectlycomparableinstructureandfunctiontoamammalianplacenta.[27]Viviparyisrareinsnakes,butboasandvipersareviviparous,givingbirthtoliveyoung. Femaleaphidgivingbirth Themajorityofinsectslayeggsbutaveryfewgivebirthtooffspringthatareminiatureversionsoftheadult.[18]Theaphidhasacomplexlifecycleandduringthesummermonthsisabletomultiplywithgreatrapidity.Itsreproductionistypicallyparthenogeneticandviviparousandfemalesproduceunfertilizedeggswhichtheyretainwithintheirbodies.[28]Theembryosdevelopwithintheirmothers'ovariolesandtheoffspringareclonesoftheirmothers.Femalenymphsarebornwhichgrowrapidlyandsoonproducemorefemaleoffspringthemselves.[29]Insomeinstances,thenewbornnymphsalreadyhavedevelopingembryosinsidethem.[18] Seealso[edit] Wikiquotehasquotationsrelatedto:Birth Animalsexualbehaviour Breedingseason Caesareansection Dystocia Episiotomy Foaling(horses) Forcepsdelivery Kegelexercises Matingsystem Odondevice Perinealmassage Reproduction Reproductivesystem Ventouse Birthspacing References[edit] ^"birth".OEDOnline.June2013.OxfordUniversityPress.Entry19395(accessed30August2013). ^abDorit,R.L.;Walker,W.F.;Barnes,R.D.(1991).Zoology.SaundersCollegePublishing.pp. 526–527.ISBN 978-0-03-030504-7. ^MarkSimmonds,WhalesandDolphinsoftheWorld,NewHollandPublishers(2007),Ch.1,p.32ISBN 1845378202. ^Crockett,Gary(2011)."HumpbackWhaleCalves".HumpbackwhalesAustralia.Archivedfromtheoriginalon2017-02-27.Retrieved2013-08-28. ^"TrunkTwins :ElephantTwinsBorninTarangire|AsiliaAfrica".AsiliaAfrica.2018-04-06.Retrieved2018-04-06. ^NICE(2007).Section1.6,Normallabour:firststage ^NICE(2007).Section1.7,Normallabour:secondstage ^NICE(2007).Section1.8,Normallabour:thirdstage ^Houston,Rob(editor);Lea,Maxine(arteditor)(2007).TheHumanBodyBook.DorlingKindersley.p. 215.ISBN 978-1-8561-3007-3.{{citebook}}:|author1=hasgenericname(help) ^ab"Calving".Alberta:AgricultureandRuralDevelopment.2000-02-01.Retrieved2013-08-28. ^"CalvingManagementinDairyHerds:TimingofInterventionandStillbirth"(PDF).TheOhioStateUniversityCollegeofVeterinaryMedicineExtension.2012.Retrieved2013-12-17. ^abcdefKustritz,M.(2005)."Reproductivebehaviourofsmallanimals".Theriogenology.64(3):734–746.doi:10.1016/j.theriogenology.2005.05.022.PMID 15946732. ^Dunn,T.J."Whelping:NewPuppiesOnTheWay!".PuppyCenter.PetMD.Retrieved2013-08-28. ^HughTyndale-Biscoe;MarilynRenfree(30January1987).ReproductivePhysiologyofMarsupials.CambridgeUniversityPress.ISBN 978-0-521-33792-2. ^"Reproductionanddevelopment".ThylacineMuseum.Retrieved2013-08-28. ^YvetteSchneiderNanette(Aug2011)."Thedevelopmentoftheolfactoryorgansinnewlyhatchedmonotremesandneonatemarsupials".J.Anat.219(2):229–242.doi:10.1111/j.1469-7580.2011.01393.x.PMC 3162242.PMID 21592102. ^SeaWorld,Sharks&RaysArchived2013-11-10attheWaybackMachine;accessed2013.09.09. ^abcdAttenborough,David(1990).TheTrialsofLife.pp. 26–30.ISBN 9780002199124. ^Adams,KyeR.;Fetterplace,LachlanC.;Davis,AndrewR.;Taylor,MatthewD.;Knott,NathanA.(January2018)."Sharks,raysandabortion:Theprevalenceofcapture-inducedparturitioninelasmobranchs".BiologicalConservation.217:11–27.doi:10.1016/j.biocon.2017.10.010.Archivedfromtheoriginalon2019-02-23.Retrieved2019-06-30. ^"Birthandcareofyoung".Animals:Sharksandrays.BuschEntertainmentCorporation.ArchivedfromtheoriginalonAugust3,2013.Retrieved2013-08-28. ^Stebbins,RobertC.;Cohen,NathanW.(1995).ANaturalHistoryofAmphibians.PrincetonUniversityPress.pp. 172–173.ISBN 978-0-691-03281-8. ^Stebbins,RobertC.;Cohen,NathanW.(1995).ANaturalHistoryofAmphibians.PrincetonUniversityPress.p. 204.ISBN 978-0-691-03281-8. ^Capinera,JohnL.,Encyclopediaofentomology.SpringerReference,2008,p.3311. ^Costa,JamesT.,TheOtherInsectSocieties.BelknapPress,2006,p.151. ^Dennis,Carina(2008-05-28)."NatureNews:Theoldestpregnantmum:Devonianfossilizedfishcontainsanembryo".Nature.453(7195):575.Bibcode:2008Natur.453..575D.doi:10.1038/453575a.PMID 18509405. ^Long,JohnA.;Trinastic,Kate;Young,GavinC.;Senden,Tim(2008-05-28)."LivebirthintheDevonianperiod".Nature.453(7195):650–652.Bibcode:2008Natur.453..650L.doi:10.1038/nature06966.PMID 18509443.S2CID 205213348. ^BlackburnDG,FlemmingAF(2012)."InvasiveimplantationandintimateplacentalassociationsinaplacentotrophicAfricanlizard,Trachylepisivensi(scincidae)".J.Morphol.273(2):137–59.doi:10.1002/jmor.11011.PMID 21956253.S2CID 5191828. ^Blackman,RogerL(1979)."Stabilityandvariationinaphidclonallineages".BiologicalJournaloftheLinneanSociety.11(3):259–277.doi:10.1111/j.1095-8312.1979.tb00038.x.ISSN 1095-8312. ^Conrad,Jim(2011-12-10)."Theaphidlifecycle".TheBackyardNatureWebsite.Retrieved2013-08-31. Citedtexts[edit] "Intrapartumcare:Careofhealthywomenandtheirbabiesduringchildbirth".NICE.September2007.Archivedfromtheoriginalon2014-04-26. Authoritycontrol:Nationallibraries Spain 2 France(data) 2(data) UnitedStates 2 3 Japan Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Birth&oldid=1063718655" Categories:BirthAnimaldevelopmentalbiologyHiddencategories:CS1errors:genericnameWebarchivetemplatewaybacklinksArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataAllarticleswithunsourcedstatementsArticleswithunsourcedstatementsfromApril2014ArticleswithBNEidentifiersArticleswithBNFidentifiersArticleswithLCCNidentifiersArticleswithNDLidentifiersArticleswithmultipleidentifiers Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English expanded collapsed Views ReadEditViewhistory More expanded collapsed Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Inotherprojects WikimediaCommonsWikiquote Languages AfrikaansالعربيةAsturianuAvañe'ẽAzərbaycancaتۆرکجهবাংলাBân-lâm-gúБеларускаяБългарскиCatalàČeštinaCymraegDanskEestiΕλληνικάEspañolEuskaraفارسیFrançaisFrysk贛語客家語/Hak-kâ-ngî한국어हिन्दीHrvatskiBahasaIndonesiaÍslenskaItalianoJawaಕನ್ನಡKreyòlayisyenLatviešuLietuviųLimburgsLingálaMalagasyമലയാളംमराठीBahasaMelayuMìng-dĕ̤ng-ngṳ̄Nederlandsनेपाली日本語NorskbokmålNorsknynorskPolskiPortuguêsRomânăРусскийᱥᱟᱱᱛᱟᱲᱤScotsShqipසිංහලSimpleEnglishسنڌيSlovenčinaSlovenščinaСловѣньскъ/ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟСрпски/srpskiSrpskohrvatski/српскохрватскиТатарча/tatarçaతెలుగుไทยTürkçeУкраїнськаاردوVahcuenghTiếngViệtWalon吴语粵語Zazaki中文 Editlinks