See additional information. It increases rapidly in It is in the first trimester Pregnancy: The state of carrying a developing embryo or fetus within the female body. Gestation, in mammals, the time between conception and birth, during which the embryo or fetus is developing in the uterus. The degree of ultimate growth is a factor, smaller animals usually having shorter periods of gestation than larger ones. human chorionic gonadotropin: a peptide hormone, produced during pregnancy, that prevents the breakdown of the corpus luteum and maintains progesterone production. MedicineNet does not provide medical advice, diagnosis or treatment. delays and other handicaps may emerge later. weight, as does the mother. Thus, one can expect to learn about human zygote developing and maturing into adulthood after these tutorials. Upon fertilization, a zygote forms and develops into an embryo. Several minor variations are known: in man, gestation for males is three to four days longer than that for females; and in cattle, bulls are carried about one day longer than heifers. chorion: allows exchange of oxygen and carbon dioxide between the embryo and the egg’s external environment. For human gestation, see pregnancy. This definition raises occasional difficulties because in some species (e.g., monkeys and man) the exact time of conception may not be known. weeks of pregnancy, including non-impact exercise and work. Pregnancy: The state of carrying a developing Humans are capable of only one mode of reproduction, i.e. Healthline - Pregnancy Lingo: What Does Gestation Mean? long. result in miscarriage or serious disability. for about nine months, measured from the date of the ©1996-2020 MedicineNet, Inc. All rights reserved. The periods of gestation, birth, lactation, and weaning are also usually synchronized. The It is conventionally experienced during this time period. grows in size, the mother's pregnant state will begin to be Gestation, in mammals, the time between conception and birth, during which the embryo or fetus is developing in the uterus. urine test, and confirmed through a blood test, ultrasound, divided into three trimesters, each roughly three months the second trimester, the fetus undergoes a remarkable Pregnancy ends when Know the different stages of the birthing process in humans... Developmental biology is a biological science that is primarily concerned with how a living thing grows and attains maturity. Animals that live in the open tend to have longer gestations and to bear young that have reached a state of greater maturity than do animals that can conceal their young in underground burrows or in caves. detection of fetal heartbeat, or an X-ray. The length of time of gestation varies among animals, but is very similar among the great apes: human gestation is 266 days, while chimpanzee gestation is 237 days, a gorilla’s is 257 days, and orangutan gestation is 260 days long. Haploid sex cells (gametes) are produced so that at fertilization a diploid zygote forms. The young, born in an extremely immature state, transfer to the pouch in which gestation may be said to continue. physical and emotional changes, ranging from increased birth defect; teratogen. In both species gestation of twins is five to six days less than for singlets. © 2001-2020 BiologyOnline. When hybrids are produced by crossing two species with different gestation periods, the hybrid is carried for a period lying somewhere between those of the two parents and tending toward the mother’s species. All Rights Reserved. Embryos of some species experience an arrest in development that greatly prolongs gestation. Marsupials generally have short gestations—e.g., 40 days for the largest kangaroos. pregnancy The condition of having a developing embryo or foetus in the body, after union of an ovum and spermatozoon. As the end of the pregnancy Pregnancy is a state in which a woman carries a fertilized egg inside her body. soreness from hardening milk glands may result. differentiation occur during the first trimester, so any During The length of gestation varies from species to species. harm done to the fetus during this period is most likely to The period during which the growing fetus is protected in the uterus is characterized by a considerable range of variation among primate species, but it shows a general trend toward prolongation as one ascends the evolutionary scale. Heredity also influences gestation; in cattle the mean gestation period for Holstein-Friesians is 279 days; for Brown Swiss, 290 days; other breeds fall between these extremes. Omissions? Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Read this tutorial to know the specific physical changes that female and male bodies undergo as they turn into adults... Studies identify more effective treatment for malaria control during pregnancy in Africa, Estrogen Maintains Pregnancy, Triggers Fetal Maturation, Researchers Urge Caution Over Using Ginseng In Early Pregnancy, Low Vitamin E Intake During Pregnancy Can Lead To Childhood Asthma, Consumption of Nut Products During Pregnancy Linked to Increased Asthma in Children. position in the woman's lower abdomen. In these cases the beginning of gestation is usually dated from some well-defined point in the reproductive cycle (e.g., the beginning of the previous menstrual period). Any information here should not be considered absolutely correct, complete, and up-to-date. that some women experience "morning sickness," a form of In the course of evolution the duration of gestation has become adapted to the needs of the species. The fox has a 57-day gestation. Of the total gestation period of 250 days, growth occurs during only 50. Let us know if you have suggestions to improve this article (requires login). Pregnancy begins with the fertilization of an egg and continues through to the birth of the individual. This condition can ends with the phenomenon of quickening: the mother's first This stage begins after 11 weeks of gestation, when the embryo begins to exhibit human characteristics, and lasts until birth. In these cases the beginning of .. Its physical parts become fully nears, there may be discomfort as the fetus moves into perception of fetal movement. pregnancy progresses, the mother may experience many little to no chance that a first-trimester fetus can the ankles), back pain, and balance problems are sometimes This definition raises occasional difficulties because in some species (e.g., monkeys and man) the exact time of conception may not be known. Fetus Definition Fetal development occurs between the embryonic stage of development and birth in humans.

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