Gestation is the period of development during the carrying of an embryo , and later fetus , inside viviparous animals (the embryo develops within the parent). It is typical for mammals , but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth .
18-415: Peramelinae Peroryctinae Echymiperinae The marsupial family Peramelidae contains the extant bandicoots . They are found throughout Australia and New Guinea , with at least some species living in every available habitat, from rainforest to desert. Four fossil peramelids are described. One known extinct species of bandicoot, the pig-footed bandicoot , was so different from the other species, it
36-489: A zygote (fertilized ovum) implants in the female's uterus and ends once the fetus leaves the uterus during labor or an abortion (whether induced or spontaneous). In humans, pregnancy can be defined clinically, biochemically or biologically. Clinically, pregnancy starts from first day of the mother's last period. Biochemically, pregnancy starts when a woman's human chorionic gonadotropin (hCG) levels rise above 25 mIU/mL. Biologically, pregnancy starts at implantation of
54-544: A gradual physiological increase in DNA damage during gestation. A positive correlation between the gestation period and maximum lifespan was observed across 740 mammalian species. It was postulated that the rates of DNA damage and senescence may impact the gestation period as well as lifespan. In viviparous animals , the embryo develops inside the body of the mother, as opposed to outside in an egg ( oviparity ). The mother then gives live birth. The less developed form of viviparity
72-446: A long, pointed snout. Peramelids are omnivorous , with soil-dwelling invertebrates forming the major part of their diet; they also eat seeds, fruit, and fungi. Their teeth are correspondingly unspecialised, with most species having the dental formula 5.1.3.4 3.1.3.4 Female peramelids have a pouch that opens to the rear and contains eight teats. The maximum litter size is, therefore, eight, since marsupial young are attached to
90-564: A variety of parental and fetal metrics, including fetal growth and heart rate, birth defects , maternal blood pressure, among others. After birth, health care providers will measure the baby's weight, vital signs, reflexes, head circumference, muscle tone, and posture to help determine the gestational age. Various factors can influence the duration of gestation, including diseases in pregnancy and adequate prenatal care. The rates of morbidity and pre-existing diseases that predispose mothers to life-threatening, pregnancy-related complications in
108-627: Is a more typical number. The gestation period of peramelids is the shortest among mammals, at just 12.5 days, the young are weaned around two months of age, and reach sexual maturity at just three months. This allows a given female to produce more than one litter per breeding season and gives peramelids an unusually high reproductive rate compared with other marsupials. Rhynchomeles Isoodon Perameles Peroryctes Echymipera Microperoryctes Isoodon Perameles Peroryctes Echymipera [incl. Rhynchomeles ] Microperoryctes The listing for extant species
126-651: Is based on The Third edition of Wilson & Reeder's Mammal Species of the World (2005), except where the Mammal Diversity Database and IUCN agree on a change. Peramelinae Peramelinae Peroryctinae Echymiperinae The marsupial family Peramelidae contains the extant bandicoots . They are found throughout Australia and New Guinea , with at least some species living in every available habitat, from rainforest to desert. Four fossil peramelids are described. One known extinct species of bandicoot,
144-444: Is based on The Third edition of Wilson & Reeder's Mammal Species of the World (2005), except where the Mammal Diversity Database and IUCN agree on a change. Gestation The time interval of a gestation is called the gestation period . In obstetrics , gestational age refers to the time since the onset of the last menses , which on average is fertilization age plus two weeks. In mammals, pregnancy begins when
162-472: Is called ovoviviparity , in which the mother carries embryos inside eggs. Most vipers exhibit ovoviviparity. The more developed form of viviparity is called placental viviparity ; mammals are the best example, but it has also evolved independently in other animals, such as in scorpions , some sharks , and in velvet worms . Viviparous offspring live independently and require an external food supply from birth. Certain lizards also employ this method such as
180-440: Is considered preterm labor and can result from multiple factors, including previous preterm deliveries. Prenatal care is important for the maintenance of a healthy pregnancy and surveillance of related complications. In high-income countries, prenatal care typically involves monthly visits during the first two trimesters, with an increasing number of visits closer to delivery. At these visits, healthcare providers will evaluate
198-439: The egg yolk rather than by the mother's body. However, the mother's body does provide gas exchange . The young of ovoviviparous amphibians are sometimes born as larvae , and undergo metamorphosis outside the body of the mother. The fish family Syngnathidae has the unique characteristic whereby females lay their eggs in a brood pouch on the male's chest, and the male incubates the eggs. Fertilization may take place in
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#1732876666359216-442: The genera Tiliqua and Corucia . The placenta is attached directly to the mother in these lizards which is called viviparous matrotrophy. Ovoviviparous animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. It is similar to viviparity in that the embryo develops within the mother's body. Unlike the embryos of viviparous species, ovoviviparous embryos are nourished by
234-407: The pig-footed bandicoot , was so different from the other species, it was recently moved into its own family. Peramelids are small marsupials, ranging in size from the mouse bandicoot , which is 15–17.5 cm long, to the giant bandicoot , which at 39–56 cm in length and up 4.7 kg in weight, is about the size of a rabbit . They have short limbs and tails, smallish, mouse-like ears, and
252-455: The United States are increasing. Inaccessibility of prenatal care may partially explain this ongoing disparity. During gestation in placental mammals there is a gradual physiological increase in senescence in the maternal decidua (the specialized layer of endometrium that forms the base of the placental bed) and in placental cells. This increase in senescence is associated with
270-490: The fertilized egg. Human pregnancy can be divided into three trimesters, each approximately three months long: the first, second, and third trimester. The first trimester is from the last menstrual period through the 13th week, the second trimester is 14th–28/29th week, and the third trimester is 29/30th–42nd week. Birth normally occurs at a gestational age of about 40 weeks, though it is common for births to occur from 37 to 42 weeks. Labor occurring prior to 37 weeks gestation
288-417: The major part of their diet; they also eat seeds, fruit, and fungi. Their teeth are correspondingly unspecialised, with most species having the dental formula 5.1.3.4 3.1.3.4 Female peramelids have a pouch that opens to the rear and contains eight teats. The maximum litter size is, therefore, eight, since marsupial young are attached to the teat during development, although two to four young per litter
306-695: The teat during development, although two to four young per litter is a more typical number. The gestation period of peramelids is the shortest among mammals, at just 12.5 days, the young are weaned around two months of age, and reach sexual maturity at just three months. This allows a given female to produce more than one litter per breeding season and gives peramelids an unusually high reproductive rate compared with other marsupials. Rhynchomeles Isoodon Perameles Peroryctes Echymipera Microperoryctes Isoodon Perameles Peroryctes Echymipera [incl. Rhynchomeles ] Microperoryctes The listing for extant species
324-430: Was recently moved into its own family. Peramelids are small marsupials, ranging in size from the mouse bandicoot , which is 15–17.5 cm long, to the giant bandicoot , which at 39–56 cm in length and up 4.7 kg in weight, is about the size of a rabbit . They have short limbs and tails, smallish, mouse-like ears, and a long, pointed snout. Peramelids are omnivorous , with soil-dwelling invertebrates forming
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