489:, that is, they lay eggs with little or no embryonic development taking place within the mother. In aquatic organisms, fertilization is nearly always external with sperm and eggs being liberated into the water (an exception is sharks and rays, which have internal fertilization). Millions of eggs may be produced with no further parental involvement, in the expectation that a small number may survive to become mature individuals. Terrestrial invertebrates may also produce large numbers of eggs, a few of which may avoid predation and carry on the species. Some fish, reptiles, and amphibians have adopted a different strategy and invest their effort in producing a small number of young at a more advanced stage which are more likely to survive to adulthood. Birds care for their young in the nest and provide for their needs after hatching and it is perhaps unsurprising that internal development does not occur in birds, given their need to fly.
427:. After further contractions, the sac is expelled and the bitch breaks the membranes, releasing clear fluid and exposing the puppy. The mother chews at the umbilical cord and licks the puppy vigorously, which stimulates it to breathe. If the puppy has not taken its first breath within about six minutes, it is likely to die. Further puppies follow in a similar way one by one usually with less straining than the first usually at 15-60-minute intervals. If a pup has not been passed in 2 hours a veterinarian should be contacted. Stage three is the passing of the placentas. This often occurs in conjunction with stage two with the passing of each offspring. The mother will then usually eat the afterbirth. This is an adaption to keep the den clean and prevent its detection by predators.
465:. When it is born, the infant is pink, blind, furless and a few centimetres long. It has nostrils in order to breathe and forelegs to cling onto its mother's hairs but its hind legs are undeveloped. It crawls through its mother's fur and makes its way into the pouch. Here it fixes onto a teat which swells inside its mouth. It stays attached to the teat for several months until it is sufficiently developed to emerge. Joeys are born with "oral shields"; in species without pouches or with rudimentary pouches these are more developed than in forms with well-developed pouches, implying a role in maintaining the young attached to the mother's nipple.
363:
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birth canal. The complete delivery of the calf (or calves in a multiple birth) signifies the end of stage two. The cow scrambles to her feet (if lying down at this stage), turns round and starts vigorously licking the calf. The calf takes its first few breaths and within minutes is struggling to rise to its feet. The third and final stage of labor is the delivery of the
446:
633:, fertilized their eggs internally. Some fishes that fertilize their eggs internally also give birth to live young, as seen here. This discovery moved our knowledge of live birth back 200 million years. The fossil of another genus was found with three embryos in the same position. Placoderms are a sister group of the ancestor of all living jawed fishes (
140:
419:, as whelping approaches, contractions become more frequent. Labour in the bitch can be divided into 3 stages. The first stage is when the cervix dilates, causing discomfort and restlessness in the dog. Common signs of this stage are panting, fasting, and/or vomiting. This may last up to 12 hours. Stage two is the passage of the offspring. The
392:
through the vulva, closely followed by the appearance of the calf's front hooves and head in a front presentation (or occasionally the calf's tail and rear end in a posterior presentation). During the second stage, the cow will usually lie down on her side to push and the calf progresses through the
353:
Large mammals which give birth to twins is much more rare, but it does occur occasionally even for mammals as large as elephants. In April 2018, approximately 8-month old elephant twins were sighted joining their mother's herd in the
Tarangire National Park of Tanzania, estimated to have been born
378:
goes through three stages of labor during normal delivery of a calf. During stage one, the animal seeks a quiet place away from the rest of the herd. Hormone changes cause soft tissues of the birth canal to relax as the mother's body prepares for birth. The contractions of the
259:, and then pumped into the main arterial system. As a result of these changes, the blood pressure in the left atrium exceeds the pressure in the right atrium, and this pressure difference forces the foramen ovale to close separating the left and right sides of the heart. The
383:
are not obvious externally, but the cow may be restless. She may appear agitated, alternating between standing and lying down, with her tail slightly raised and her back arched. The fetus is pushed toward the birth canal by each contraction and the cow's
191:
and gradual dilation of the cervix. The active phase of the first stage starts when the cervix is dilated more than about 4 cm in diameter and is when the contractions become stronger and regular. The head (or the buttocks in a
349:
In the case of whales, dolphins and porpoises, the single calf is normally born tail first which minimizes the risk of drowning. The mother encourages the newborn calf to rise to the surface of the water to breathe.
679:, give birth to live young that develop internally, deriving their nourishment from a mammal-like placenta attached to the inside of the mother's uterus. In a recently described example, an African species,
461:
is born in a very immature state. The gestation period is usually shorter than the intervals between oestrus periods. The first sign that a birth is imminent is the mother cleaning out her
388:
gradually begins to dilate. Stage one may last several hours, and ends when the cervix is fully dilated. Stage two can be seen to be underway when there is external protrusion of the
212:
or breaking the water). In stage two, starting when the cervix is fully dilated, strong contractions of the uterus and active pushing by the mother expels the baby out through the
187:). The normal process of childbirth takes several hours and has three stages. The first stage starts with a series of involuntary contractions of the muscular walls of the
346:. This means that it is born in a more advanced state than a human baby and is able to stand, walk and run (or swim in the case of an aquatic mammal) shortly after birth.
235:
is dependent on circulation of blood through the placenta for sustenance including gaseous exchange and the unborn baby's blood bypasses the lungs by flowing through the
606:. In these, the developing embryo is nourished by some form of placental structure. The earliest known placenta was found recently in a group of extinct fishes called
527:
the eggs hatch in the oviduct within the mother's body and the embryos are nourished by the egg's yolk and fluids secreted by glands in the walls of the oviduct. The
1650:
Blackburn DG, Flemming AF (2012). "Invasive implantation and intimate placental associations in a placentotrophic
African lizard, Trachylepis ivensi (scincidae)".
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are born which grow rapidly and soon produce more female offspring themselves. In some instances, the newborn nymphs already have developing embryos inside them.
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are ovoviviparous and give birth to already developed offspring. When the young have finished their yolk sacs they feed on nutrients secreted by cells lining the
557:. This is more analogous to mammalian gestation than to that of other fishes. In all these cases, the young are born alive and fully functional. The majority of
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It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are
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and viviparous and females produce unfertilized eggs which they retain within their bodies. The embryos develop within their mothers'
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are ovoviviparous, developing through the larval stage inside the mother's oviduct and eventually emerging as fully formed juveniles.
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has a complex life cycle and during the summer months is able to multiply with great rapidity. Its reproduction is typically
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216:, which during this stage of labour is called a birth canal as this passage contains a baby, and the baby is born with
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The majority of insects lay eggs but a very few give birth to offspring that are miniature versions of the adult. The
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This article is primarily about birth in non-human mammals and other animals. For birth in humans specifically, see
842:
1231:
1569:
Long, John A.; Trinastic, Kate; Young, Gavin C.; Senden, Tim (2008-05-28). "Live birth in the
Devonian period".
1357:
Adams, Kye R.; Fetterplace, Lachlan C.; Davis, Andrew R.; Taylor, Matthew D.; Knott, Nathan A. (January 2018).
362:
1693:
Neill, Wilfred T. (January 1964). "Viviparity in Snakes: Some
Ecological and Zoogeographical Considerations".
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are viviparous, giving birth to live young. Some are ovoviviparous but others such as members of the genera
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In these large animals, the birth process is similar to that of a human, though in most the offspring is
247:. After birth the umbilical cord is clamped and cut, the baby starts to breathe air, and blood from the
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that remain in the mother's body until they are ready to hatch. Ovoviviparous animals are similar to
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attached. In stage three, which begins after the birth of the baby, further contractions expel the
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are not needed for life in air and in time these vessels become ligaments (embryonic remnants).
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Humans usually produce a single offspring at a time. The mother's body is prepared for birth by
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to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe.
200:, which gradually dilates until it is fully dilated at 10 cm diameter. At some time, the
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Many reptiles and the vast majority of invertebrates, most fish, amphibians and all birds are
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224:, amniotic sac, and the remaining portion of the umbilical cord usually within a few minutes.
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1258:"The development of the olfactory organs in newly hatched monotremes and neonate marsupials"
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1359:"Sharks, rays and abortion: The prevalence of capture-induced parturition in elasmobranchs"
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directly comparable in structure and function to a mammalian placenta. Vivipary is rare in
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with one offspring at a time, although they may have twin or multiple births on occasion.
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74:. In mammals, the process is initiated by hormones which cause the muscular walls of the
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period, 380 million years ago, was found with an embryo inside it connected by an
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looking like a glistening grey balloon, with a puppy inside, is propelled through the
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starts to flow to the lungs for gaseous exchange and oxygenated blood returns to the
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to birth is normally about 38 weeks (birth usually occurring 40 weeks after the last
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523:(respiration), but that is largely necessary for oviparous animals as well. In many
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1522:"Nature News: The oldest pregnant mum: Devonian fossilized fish contains an embryo"
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and even the cells themselves which they eat with specialist scraping teeth. The
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Blackman, Roger L (1979). "Stability and variation in aphid clonal lineages".
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1794:"Intrapartum care: Care of healthy women and their babies during childbirth"
1088:. The Ohio State University College of Veterinary Medicine Extension. 2012.
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and the young are born in an advanced state, but differ in that there is no
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629:. The find confirmed the hypothesis that a sub-group of placoderms, called
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1083:"Calving Management in Dairy Herds: Timing of Intervention and Stillbirth"
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and can move around almost immediately after birth but in others, it is
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1026:"Trunk Twins : Elephant Twins Born in Tarangire | Asilia Africa"
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Enormous changes take place in the newborn's circulation to enable
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537:, where the first embryos to hatch consume the remaining eggs and
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59:: the mother licks the first lamb while giving birth to the second
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96:, the fetus is born at a very immature stage after a short
1060:. Alberta: Agriculture and Rural Development. 2000-02-01.
119:
developing inside their body, as in the case of mammals.
1204:
Hugh
Tyndale-Biscoe; Marilyn Renfree (30 January 1987).
553:
link to the developing young, this practice is known as
573:) and several species of Tanzanian toad in the genus
862:Dorit, R. L.; Walker, W. F.; Barnes, R. D. (1991).
66:is the act or process of bearing or bringing forth
1422:. Busch Entertainment Corporation. Archived from
515:connection and the unborn young are nourished by
453:joey firmly attached to a nipple inside the pouch
1448:. Princeton University Press. pp. 172–173.
411:Canine reproduction § Gestation and litters
1327:
1325:
1323:
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1469:Stebbins, Robert C.; Cohen, Nathan W. (1995).
1444:Stebbins, Robert C.; Cohen, Nathan W. (1995).
929:Houston, Rob; Lea, Maxine (art), eds. (2007).
239:, which is a hole in the septum dividing the
8:
699:are viviparous, giving birth to live young.
70:, also referred to in technical contexts as
1473:. Princeton University Press. p. 204.
1003:. Humpback whales Australia. Archived from
100:and develops further in its mother's womb
1622:"Chamaeleo jacksonii (Jacksons chameleon)"
1052:
1050:
1730:Biological Journal of the Linnean Society
1545:
1281:
1126:"Reproductive behaviour of small animals"
868:. Saunders College Publishing. pp.
415:Birth is termed whelping in dogs. Among
857:
855:
827:
89:and completely dependent on parenting.
838:. June 2013. Oxford University Press.
41:"Parturition" redirects here. For the
1256:Yvette Schneider Nanette (Aug 2011).
1207:Reproductive Physiology of Marsupials
1119:
1117:
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1111:
1109:
7:
1497:. Springer Reference, 2008, p. 3311.
1142:10.1016/j.theriogenology.2005.05.022
437:Marsupial § Reproductive system
196:) of the baby is pushed against the
1176:"Whelping: New Puppies On The Way!"
962:. Bloomsbury Wildlife. p. 32.
683:, has developed a purely reptilian
594:and cockroaches, certain genera of
495:is a mode of reproduction in which
1742:10.1111/j.1095-8312.1979.tb00038.x
545:consume neighbouring embryos. The
441:Marsupial § Early development
81:In some species, the offspring is
25:
481:giving birth (100x magnification)
374:is typical of a larger mammal. A
1800:. September 2007. Archived from
1274:10.1111/j.1469-7580.2011.01393.x
960:Whales and Dolphins of the World
155:and the cervix is fully dilated.
47:Parturition (Star Trek: Voyager)
1771:from the original on 2019-03-18
1767:. The Backyard Nature Website.
1632:from the original on 2023-02-05
1471:A Natural History of Amphibians
1446:A Natural History of Amphibians
1238:from the original on 2017-06-21
1186:from the original on 2018-08-24
1156:from the original on 2016-11-18
1095:from the original on 2013-12-19
1064:from the original on 2013-09-12
1036:from the original on 2018-04-07
590:is adopted by some species of
135:Adaptation to extrauterine life
1510:. Belknap Press, 2006, p. 151.
1232:"Reproduction and development"
1210:. Cambridge University Press.
1:
1520:Dennis, Carina (2008-05-28).
641:, the sharks & rays, and
519:. The mother's body provides
1824:Animal developmental biology
1383:10.1016/j.biocon.2017.10.010
1332:Attenborough, David (1990).
958:Simmonds, Mark (2007). "1".
27:Process of bearing offspring
1336:. Collins. pp. 26–30.
906:Normal labour: second stage
255:, which is pumped into the
231:in air. In the uterus, the
1840:
1763:Conrad, Jim (2011-12-10).
1508:The Other Insect Societies
1495:Encyclopedia of entomology
918:Normal labour: third stage
916:NICE (2007). Section 1.8,
904:NICE (2007). Section 1.7,
894:Normal labour: first stage
892:NICE (2007). Section 1.6,
849:(accessed 30 August 2013).
434:
408:
143:An illustration of normal
132:
126:
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29:
1416:"Birth and care of young"
730:of their mothers. Female
582:A more developed form of
507:species in that there is
1420:Animals: Sharks and rays
1695:The American Naturalist
1363:Biological Conservation
1001:"Humpback Whale Calves"
999:Crockett, Gary (2011).
745:Animal sexual behaviour
208:escapes (also known as
153:membranes have ruptured
145:head-first presentation
1765:"The aphid life cycle"
1315:; accessed 2013.09.09.
726:and the offspring are
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509:internal fertilization
482:
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36:Birth (disambiguation)
34:. For other uses, see
1124:Kustritz, M. (2005).
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409:Further information:
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151:from about 1792. The
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133:Further information:
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1626:Animal Diversity Web
1620:Kundinger, Heather.
1234:. Thylacine Museum.
663:and many species of
588:placental viviparity
210:rupture of membranes
147:by the obstetrician
1591:10.1038/nature06966
1583:2008Natur.453..650L
1538:2008Natur.453..575D
1493:Capinera, John L.,
1375:2018BCons.217...11A
931:The Human Body Book
805:Reproductive system
657:Jackson's chameleon
648:Among lizards, the
645:, the bony fishes.
617:, laid down in the
1664:10.1002/jmor.11011
1334:The Trials of Life
1311:2013-11-10 at the
935:Dorling Kindersley
845:2022-11-22 at the
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681:Trachylepis ivensi
637:), including both
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366:A cow giving birth
265:umbilical arteries
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1577:(7195): 650–652.
1506:Costa, James T.,
1480:978-0-691-03281-8
1455:978-0-691-03281-8
1426:on August 3, 2013
1306:Sharks & Rays
1217:978-0-521-33792-2
969:978-1-84537-820-2
944:978-1-8561-3007-3
879:978-0-03-030504-7
755:Caesarean section
650:viviparous lizard
567:Alpine salamander
543:cannibalistically
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429:
406:
403:
359:
356:
309:hippopotamuses
280:
277:
269:ductus venosus
261:umbilical vein
257:left ventricle
218:umbilical cord
206:amniotic fluid
127:Main article:
124:
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26:
24:
14:
13:
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9:
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1658:(2): 137–59.
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1532:(7195): 575.
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1030:Asilia Africa
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1007:on 2017-02-27
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815:Birth spacing
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785:Mating system
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631:ptyctodontids
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493:Ovoviviparity
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469:Other animals
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279:Other mammals
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237:foramen ovale
234:
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181:fertilization
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109:ovoviviparous
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45:episode, see
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19:
1802:the original
1773:. Retrieved
1758:
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1634:. Retrieved
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1428:. Retrieved
1424:the original
1419:
1410:
1399:. Retrieved
1395:the original
1366:
1362:
1352:
1333:
1300:
1265:
1261:
1251:
1240:. Retrieved
1226:
1206:
1199:
1188:. Retrieved
1180:Puppy Center
1179:
1169:
1158:. Retrieved
1133:
1129:
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1077:
1066:. Retrieved
1038:. Retrieved
1029:
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1009:. Retrieved
1005:the original
994:
959:
953:
930:
924:
917:
912:
905:
900:
893:
888:
864:
830:
800:Reproduction
713:
710:giving birth
680:
674:
668:
652:
647:
643:Osteichthyes
604:velvet worms
581:
574:
570:
550:
532:
521:gas exchange
491:
484:
456:
421:amniotic sac
414:
390:amniotic sac
370:Birthing in
369:
352:
348:
341:
313:rhinoceroses
282:
241:right atrium
226:
202:amniotic sac
194:breech birth
175:. The total
158:
106:
91:
80:
71:
63:
62:
42:
1787:Cited texts
1304:Sea World,
1174:Dunn, T.J.
840:Entry 19395
790:Odon device
612:Australia's
549:maintain a
399:herbivorous
253:left atrium
245:left atrium
115:, with the
72:parturition
1813:Categories
1775:2013-08-31
1652:J. Morphol
1636:2023-02-27
1430:2013-08-28
1401:2019-06-30
1242:2013-08-28
1190:2013-08-28
1182:. Pet MD.
1160:2016-11-18
1099:2013-12-17
1068:2013-08-28
1040:2018-04-06
1011:2013-08-28
836:OED Online
822:References
765:Episiotomy
661:slow worms
608:placoderms
584:viviparity
559:caecilians
555:viviparity
529:Lamniforme
505:viviparous
457:An infant
435:See also:
431:Marsupials
287:, such as
129:Childbirth
113:viviparous
94:marsupials
32:Childbirth
1750:1095-8312
1607:205213348
1369:: 11–27.
1058:"Calving"
978:159685085
834:"birth".
724:ovarioles
592:scorpions
551:placental
513:placental
487:oviparous
479:Cladocera
459:marsupial
344:precocial
333:porpoises
317:elephants
301:antelopes
229:breathing
98:gestation
87:altricial
83:precocial
68:offspring
43:Star Trek
1769:Archived
1715:85209921
1672:21956253
1630:Archived
1599:18509443
1556:18509405
1391:90834034
1309:Archived
1292:21592102
1236:Archived
1184:Archived
1154:Archived
1150:15946732
1090:Archived
1062:Archived
1034:Archived
986:9540216M
843:Archived
810:Ventouse
760:Dystocia
738:See also
685:placenta
627:yolk sac
619:Devonian
517:egg yolk
451:kangaroo
395:placenta
337:pregnant
329:dolphins
305:giraffes
289:primates
222:placenta
173:placenta
171:and the
161:hormones
18:Whelping
1680:5191828
1579:Bibcode
1534:Bibcode
1371:Bibcode
1283:3162242
1262:J. Anat
870:526–527
865:Zoology
706:Female
676:Corucia
670:Tiliqua
586:called
563:oviduct
534:oophagy
497:embryos
299:, some
285:mammals
57:Lambing
1748:
1713:
1678:
1670:
1605:
1597:
1571:Nature
1554:
1526:Nature
1477:
1452:
1389:
1340:
1290:
1280:
1214:
1148:
984:
976:
966:
941:
876:
732:nymphs
728:clones
697:vipers
691:, but
689:snakes
655:, the
600:snakes
596:sharks
525:sharks
439:, and
386:cervix
381:uterus
372:cattle
358:Cattle
331:, and
325:whales
297:horses
293:cattle
283:Large
214:vagina
198:cervix
189:uterus
167:, the
117:embryo
76:uterus
1819:Birth
1711:S2CID
1676:S2CID
1603:S2CID
1387:S2CID
1093:(PDF)
1086:(PDF)
716:aphid
708:aphid
665:skink
625:to a
541:pups
463:pouch
425:vulva
401:cow.
321:seals
233:fetus
179:from
169:ovary
102:pouch
64:Birth
1798:NICE
1746:ISSN
1668:PMID
1595:PMID
1552:PMID
1475:ISBN
1450:ISBN
1338:ISBN
1288:PMID
1212:ISBN
1146:PMID
974:OCLC
964:ISBN
939:ISBN
874:ISBN
695:and
693:boas
673:and
602:and
501:eggs
417:dogs
405:Dogs
271:and
243:and
1738:doi
1703:doi
1660:doi
1656:273
1587:doi
1575:453
1542:doi
1530:453
1379:doi
1367:217
1278:PMC
1270:doi
1266:219
1138:doi
376:cow
92:In
1815::
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