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Some degree of weight gain is expected during pregnancy. The enlarging uterus, growing fetus, placenta, amniotic fluid, normal increase in body fat, and increase in water retention all contribute weight gain during pregnancy. The amount of weight gain can vary from 5 pounds (2.3 kg) to over 100 pounds (45 kg).
The amniotic sac, also called the bag of waters[1][2] or the membranes, [3] is the sac in which the embryo and later fetus develops in amniotes. It is a thin but tough transparent pair of membranes that hold a developing embryo (and later fetus) until shortly before birth. The inner of these membranes, the amnion, encloses the amniotic cavity ...
Nine-week-old human embryo from an ectopic pregnancy. Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.
Uterus. The uterus (from Latin uterus, pl.: uteri) or womb (/ wuːm /) is the organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic and fetal development of one or more fertilized eggs until birth. [1] The uterus is a hormone -responsive sex organ that contains glands in its lining that ...
The yolk sac is the first element seen within the gestational sac during pregnancy, [1] usually at 3 days gestation. The yolk sac is situated on the front ( ventral ) part of the embryo ; it is lined by extra-embryonic endoderm , [ 3 ] outside of which is a layer of extra-embryonic mesenchyme , derived from the epiblast.
The volume of amniotic fluid changes with the growth of fetus. From the 10th to the 20th week it increases from 25 to 400 millilitres (0.88 to 14.08 imp fl oz; 0.85 to 13.53 US fl oz) approximately. [3] Approximately in the 10th–11th week, the breathing and swallowing of the fetus slightly decrease the amount of fluid.
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization, and continues as fetal development. By the end of the tenth week of gestational age, the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where ...
The mean sac diameter [3] can effectively estimate the gestational age [4] between 5 and 6 weeks, with an accuracy of about +/- 5 days. [ 5 ] The yolk sac and embryo should be readily identifiable when the gestational sac reaches a certain size — a yolk sac should be seen when the gestational sac is 20mm and a fetal pole should be seen when ...