Gestation is the carrying of an embryo or fetus inside a female viviparous animal. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular A fetus (or foetus or fœtus) is a developing Mammal or other Viviparous Vertebrate, after the Embryonic stage and Female (♀ is the Sex of an Organism, or a part of an organism which produces ova (egg cells A viviparous Animal is an animal employing vivipary: the embryo develops inside the body of the mother as opposed to outside in an egg ( Ovipary Mammals during pregnancy can have one or more gestations at the same time (multiple gestations). In mammals pregnancy is the period of Reproduction during which a Female carries one or more live offspring from Implantation in the uterus through A multiple birth occurs when more than one Fetus is carried to term in a single Pregnancy. The time interval of a gestation plus 2 weeks is called gestation period, and the length of time plus 2 weeks that the offspring have spent developing in the uterus is called gestational age. Gestational age is usually considered to be the age of an Embryo or Fetus (or newborn infant from the first day of the woman's last menstrual period (LMP (The extra 2 weeks is because gestational age is counted starting from the last menstrual period (LMP), rather than actual conception. However this extra 2 weeks is not always added when talking about animals. )
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Humans
Human pregnancy can be divided into three trimesters, each three months long. Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female The third trimester begins at about 28 weeks.
In humans, birth normally occurs at a gestational age of 37 to 42 weeks. Childbirth occurring before 37 weeks of gestation is considered preterm, childbirth after 25 weeks is usually considered "viable". [1] Preterm and low birth weight babies make up the second leading cause of infant death at about 17%. Preterm births solely consist of 12% of infant deaths with an 84% majority within the 32-36 week period. [2] It is estimated that two million babies worldwide die annually within 24 hours of birth.
Mammals
In mammals, pregnancy begins when a fertilized zygote implants in the female's uterus and ends once it leaves the uterus. In mammals pregnancy is the period of Reproduction during which a Female carries one or more live offspring from Implantation in the uterus through For soil improvement see Fertilization (soil. For other meanings see Zygote (disambiguation. A zygote (from Greek ζυγωτός zugōtos "joined" or "yoked" The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the
Below are average and approximate values ordered by gestation period (note for humans gestational age is counted from the LMP, for other animals the counting method varies, so these figures could be 14 days off):
| Animal | Average gestation period (days) |
|---|---|
| Rabbits | 33 |
| Cats | 62 |
| Dogs | 65 |
| Lions | 108 |
| Pigs | 115 |
| Sheep | 150 |
| Humans | 259-294 |
| Cattle | 283 |
| Horses | 336 |
| Elephants | 600-660 |
Non-mammals
A viviparous animal is an animal employing vivipary: the embryo develops inside the body of the mother, as opposed to outside in an egg (ovipary). Rabbits are small Mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world WikipediaManual of Style (spelling, articles should conform to one overall spelling style of English typically the one most linked to the article topic (if it is geographic The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order The lion ( Panthera leo) is a member of the family Felidae and one of four Big cats in the Genus Panthera. Pigs, also called hogs or' swine', are Ungulates which have been domesticated as sources of food leather and similar products since ancient times Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus Cattle, colloquially referred to as cows, are domesticated Ungulates a member of the Subfamily Bovinae of the family The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. Elephants ( family: Elephantidae) are large land Mammals of the order Proboscidea. In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. Oviparous animals are animals that lay eggs, with little or no other Embryonic development within the mother The mother then gives live birth. A live birth occurs when a Fetus, whatever its Gestational age, exits the Maternal body and subsequently shows any sign of life such as voluntary The less developed form of vivipary is called ovoviviparity, which, for instance, occurs in most vipers. Ovoviviparous Animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch The Viperidae are a family of Venomous snakes commonly referred to as vipers, although the term viperids is more specific and distinguishes them from The more developed form of vivipary 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. The placenta is an Ephemeral organ present in placental Vertebrates, such as Eutherial Mammals and Sharks during Gestation Scorpions are eight-legged Carnivorous Arthropods They are members of the order Scorpiones within the class Arachnida. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body The velvet worms ( Onychophora — literally "claw bearers" form a Clade within the Ecdysozoa and can be simply described as " Worms Viviparous offspring live independently and require an external food supply from birth. Certain lizards also employ this method such as 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. In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. This strategy of birth is known as ovoviviparity. Childbirth (also called labour, birth, partus or parturition) is the culmination of a Human Pregnancy or It is similar to vivipary in that the embryo develops within the mother's body. A viviparous Animal is an animal employing vivipary: the embryo develops inside the body of the mother as opposed to outside in an egg ( Ovipary Unlike the embryos of viviparous species, ovoviviparous embryos are nourished by the egg yolk rather than by the mother's body. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular An egg yolk is the part of an egg which serves as the Food source for the developing Embryo inside However, the mother's body does provide gas exchange. Gas exchange or respiration takes place at a respiratory surface—a boundary between the external environment and the interior of the body Ovoviviparity is employed by many aquatic life forms such as fish and some sharks, reptiles, and invertebrates. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate The young of ovoviviparous amphibians are sometimes born as larvae, and undergo metamorphosis outside the body of the mother. Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example Metamorphosis is a Biological process by which an Animal physically develops after Birth or hatching involving a conspicuous and relatively
The Syngnathidae family of fish has the unique characteristic where females lay their eggs in a brood pouch on the male's chest, and the male incubates the eggs. Syngnathidae is a family of fish which includes the Seahorses the Pipefishes and the weedy and Leafy sea dragons Fish of this family have In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. Fertilization may take place in the pouch or before implantation in the water. Included in Syngnathidae are seahorses, the pipefish, and the weedy and leafy sea dragons. Seahorses are a Genus ( Hippocampus ') of fish belonging to the family Syngnathidae, which also includes Pipefish and Leafy Pipefishes or pipe-fishes ( Syngnathinae) are a subfamily of small Fishes which with the Seahorses form a distinct family The weedy sea dragon or common sea dragon ( Phyllopteryx taeniolatus) is a marine Fish related to the Seahorse. The leafy sea dragon, Phycodurus eques, is a marine Fish related to the Seahorse. Syngnathidae is the only family in the animal kingdom to which the term "male pregnancy" has been applied. [3]
References
- ^ March of Dimes - Preterm labor and birth
- ^ March of Dimes - Preterm Birth
- ^ Jones, Adam G. ; Avise, John C. (2003-10-14). Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Events 1066 - Norman Conquest: Battle of Hastings - In England on Senlac Hill seven miles from Hastings, the forces "Male Pregnancy" (HTML). HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure Current Biology 13 (20): R791. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
See also
Further reading
Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female In mammals pregnancy is the period of Reproduction during which a Female carries one or more live offspring from Implantation in the uterus through Nesting instinct refers to an instinct or urge in pregnant animals to prepare a home for the upcoming newborn(s Prenatal development is the process in which an embryo or fetus (or foetus) gestates during Pregnancy, from fertilizationDictionary
gestation
-noun
- The act of wearing (clothes or ornaments).
- The act of carrying young in the womb from conception to delivery; pregnancy.
- Exercise in which one is borne or carried, as on horseback, or in a carriage, without the exertion of his own powers; passive exercise.
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