Birth

==Other mammals==
Large [[mammal]]s, such as [[primate]]s, [[cattle]], [[horse]]s, some [[antelope]]s, [[giraffe]]s, [[hippopotamus]]es, [[rhinoceros]]es, [[elephant]]s, [[Pinniped|seals]], [[whale]]s, [[dolphin]]s, and [[porpoise]]s, generally are [[Pregnancy (mammals)|pregnant]] with one offspring at a time, although they may have twin or multiple births on occasion.

In these large animals, the birth process is similar to that of a human, though in most the offspring is [[precocial]]. 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.<ref name=Dorit/>

In the case of whales, dolphins and porpoises, the single calf is normally born tail first which minimizes the risk of drowning.<ref name="Simmonds 2007 p.32">{{cite book | last=Simmonds | first=Mark | title=Whales and Dolphins of the World | publisher=Bloomsbury Wildlife | date=2007 | isbn=978-1-84537-820-2 | oclc=159685085 | ol=9540216M | chapter=1 | page=32}}</ref> The mother encourages the newborn calf to rise to the surface of the water to breathe.<ref>{{cite web |url=http://humpbackwhale.homestead.com/Humpback-Whale-Calf.html |title=Humpback Whale Calves |author=Crockett, Gary |year=2011 |publisher=Humpback whales Australia |access-date=2013-08-28 |archive-url=https://web.archive.org/web/20170227041536/http://humpbackwhale.homestead.com/Humpback-Whale-Calf.html |archive-date=2017-02-27 |url-status=dead }}</ref>

Most smaller mammals have multiple births, producing litters of young which may number twelve or more. In these animals, each fetus is surrounded by its own amniotic sac and has a separate placenta. This separates from the wall of the uterus during labor and the fetus works its way towards the birth canal.{{citation needed|date=April 2014}}

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 in August 2017.<ref>{{Cite news|url=https://www.asiliaafrica.com/trunk-twins-elephant-twins-born-in-tarangire/|title=Trunk Twins : Elephant Twins Born in Tarangire {{!}} Asilia Africa|date=2018-04-06|work=Asilia Africa|access-date=2018-04-06|language=en-GB|archive-date=2018-04-07|archive-url=https://web.archive.org/web/20180407001742/https://www.asiliaafrica.com/trunk-twins-elephant-twins-born-in-tarangire/|url-status=live}}</ref>

===Cattle===
[[File:Cow giving birth, in Laos (step by step).jpg|thumb|alt=Series of photos showing a cow giving birth|A cow giving birth]]
Birthing in [[cattle]] is typical of a larger mammal. A [[cow]] 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 [[uterus]] 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 [[cervix]] 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 [[amniotic sac]] 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).<ref name=Alberta/>  During the second stage, the cow will usually lie down on her side to push and the calf progresses through the 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 [[placenta]], which is usually expelled within a few hours and is often eaten by the normally [[Herbivore|herbivorous]] cow.<ref name=Alberta>{{cite web |url=http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3451 |title=Calving |date=2000-02-01 |publisher=Alberta: Agriculture and Rural Development |access-date=2013-08-28 |archive-date=2013-09-12 |archive-url=https://web.archive.org/web/20130912011555/http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3451 |url-status=live }}</ref><ref name=ohio>{{cite web |url=http://ohioline.osu.edu/vme-fact/pdf/0029.pdf |title=Calving Management in Dairy Herds: Timing of Intervention and Stillbirth |year=2012 |publisher=The Ohio State University College of Veterinary Medicine Extension |access-date=2013-12-17 |archive-date=2013-12-19 |archive-url=https://web.archive.org/web/20131219005040/http://ohioline.osu.edu/vme-fact/pdf/0029.pdf |url-status=live }}</ref>

===Dogs===
{{Further|Canine reproduction#Gestation and litters}}
Birth is termed whelping in dogs.<ref name=":0">{{Cite journal|last=Kustritz, M.|year=2005|title=Reproductive behaviour of small animals|url=https://www.scribd.com/document/263302746/Conducta-Reproductiva-en-Pequenos-Animales|journal=Theriogenology|volume=64|issue=3|pages=734–746|doi=10.1016/j.theriogenology.2005.05.022|pmid=15946732|access-date=2016-11-18|archive-date=2016-11-18|archive-url=https://web.archive.org/web/20161118041254/https://www.scribd.com/document/263302746/Conducta-Reproductiva-en-Pequenos-Animales|url-status=live}}</ref> Among [[dog]]s, 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.<ref name=":0" /> Stage two is the passage of the offspring.<ref name=":0" /> The [[amniotic sac]] looking like a glistening grey balloon, with a puppy inside, is propelled through the [[vulva]].  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.<ref name=":0" /> Stage three is the passing of the placentas. This often occurs in conjunction with stage two with the passing of each offspring.<ref name=":0" /> The mother will then usually eat the afterbirth.<ref name=petmd>{{cite web |url=http://www.petmd.com/dog/puppycenter/health/evr_dg_whelping_new_puppies_on_the_way |title=Whelping: New Puppies On The Way! |author=Dunn, T.J. |work=Puppy Center |publisher=Pet MD |access-date=2013-08-28 |archive-date=2018-08-24 |archive-url=https://web.archive.org/web/20180824034316/https://www.petmd.com/dog/puppycenter/health/evr_dg_whelping_new_puppies_on_the_way |url-status=live }}</ref> This is an adaption to keep the den clean and prevent its detection by predators.<ref name=":0" />

===Marsupials===
{{See also|Marsupial#Reproductive system|Marsupial#Early development}}
[[File:Joey in pouch.jpg|thumb|A [[kangaroo]] joey firmly attached to a nipple inside the pouch]]
An infant [[marsupial]] is born in a very immature state.<ref name="Tyndale-BiscoeRenfree1987">{{cite book|author1=Hugh Tyndale-Biscoe|author2=Marilyn Renfree|title=Reproductive Physiology of Marsupials|url=https://books.google.com/books?id=HpjovN0vXW4C&q=birth|date=30 January 1987|publisher=Cambridge University Press|isbn=978-0-521-33792-2}}</ref> 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 [[Pouch (marsupial)|pouch]]. 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.<ref>{{cite web |url=http://www.naturalworlds.org/thylacine/biology/reproduction/reproduction_5.htm |title=Reproduction and development |publisher=Thylacine Museum |access-date=2013-08-28 |archive-date=2017-06-21 |archive-url=https://web.archive.org/web/20170621040826/http://www.naturalworlds.org/thylacine/biology/reproduction/reproduction_5.htm |url-status=live }}</ref> 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.<ref>{{cite journal | author = Yvette Schneider Nanette | date = Aug 2011 | title = The development of the olfactory organs in newly hatched monotremes and neonate marsupials | journal = J. Anat. | volume = 219 | issue = 2| pages = 229–242 | doi = 10.1111/j.1469-7580.2011.01393.x | pmc = 3162242 | pmid=21592102}}</ref>