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Information about Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time (multiple gestations). According to the National Center for Health and Statistics there were over 136,000 multiple human births documented in the United States in 2003(NCHS). [1] The time interval of a gestation is called gestation period, and the length of time the offspring have spent developing in the uterus is called gestational age.

Humans

Main article: Pregnancy
Human pregnancy can be divided into three trimesters, each three months long. The third trimester begins at about 28 weeks. The 23rd week is the first week when a preterm fetus is considered viable. Before this age major developmental events that would allow the fetus to survive outside the womb have not yet occurred. This division is somewhat arbitrary as children born before this point have survived, but only with significant medical assistance.

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". [2] 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. [3] It is estimated that two million babies worldwide die annually within 24 hours of birth.

Mammals

Main article: Pregnancy (mammals)


In mammals, pregnancy begins when a fertilized zygote implants in the female's uterus; and ends once it leaves the uterus.

Below are average and approximate values ordered by gestation period:

Animal Average gestation period (days)
Rabbits33
Cats62
Dogs65
Lions108
Pigs115
Sheep150
Humans259-294
Cattle283
Horses336
Elephants600-660

References

External links

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fetus (or foetus, or fœtus) is a developing mammal or other viviparous vertebrate, after the embryonic stage and before birth. The plural is fetuses (foetuses, fœtuses) or, very rarely, foeti.
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Female (♀) is the sex of an organism, or a part of an organism, which produces ova (egg cells). The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon is produced by the male.
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viviparous animal is an animal employing vivipary: the embryo develops inside the body of the mother, as opposed to outside in an egg (ovipary). The mother then gives live birth.
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pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus; and ends once it leaves the uterus.
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multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple birth are utilized, depending on the number of offspring. Common multiples are two and three, known as twins and triplets respectively.
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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).[1] [2]
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Pregnancy is the carrying of one or more offspring, known as a fetus or embryo, inside the body of a female mammal such as a human. In a pregnancy, there can be multiple gestations (for example, in the case of twins or triplets).
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pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus; and ends once it leaves the uterus.
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Fertilization (also known as conception, fecundation and syngamy), is fusion of gametes to form a new organism of the same species. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo.
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For other meanings see Zygote (disambiguation).
A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization.
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uterus or womb is the major female reproductive organ of most mammals, including humans. One end, the cervix, opens into the vagina; the other is connected on both sides to the fallopian tubes.
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Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are seven different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), cottontail rabbit (genus
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F. s. catus

Trinomial name
Felis silvestris catus
(Linnaeus, 1758)

Synonyms
Felis lybica invalid junior synonym
Felis catus invalid junior synonym[2]

The cat (
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C. l. familiaris

Trinomial name
Canis lupus familiaris
(Linnaeus, 1758)

The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora.
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P. leo

Binomial name
Panthera leo
(Linnaeus, 1758)

Distribution of lions in Africa


Synonyms
Felis leo
(Linnaeus, 1758)

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Sus
Linnaeus, 1758

Species

Sus barbatus
Sus bucculentus†
Sus cebifrons
Sus celebensis
Sus domestica
Sus falconeri†
Sus heureni

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H.O.R.S.E. is a form of poker commonly played at the high stakes tables of casinos. It consists of rounds of play cycling among:
  • Texas Hold 'em,
  • Omaha eight or better,
  • Razz,
  • Seven card Stud, and
  • Seven card stud E

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Elephantidae
Gray, 1821

Subfamilia
  • See Classification
The elephants (Elephantidae) are a family in the order Proboscidea in the class Mammalia.
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