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For most species, the amount a fetus grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period than larger animals. [ 2 ] For example, a cat's gestation normally takes 58–65 days while an elephant's takes nearly 2 years (21 months). [ 3 ]
Placental expulsion (also called afterbirth) occurs when the placenta comes out of the birth canal after childbirth.The period of time starting just after the baby is expelled until just after the placenta is expelled is called the third stage of labor.
In live bearing mammals, the placenta forms after the embryo implants into the wall of the uterus. The developing fetus is connected to the placenta via an umbilical cord. Mammalian placentas can be classified based on the number of tissues separating the maternal from the fetal blood. These include: endotheliochorial placentation
This begins with contractions of the uterus and dilation of the cervix. The fetus then descends to the cervix, where it is pushed out into the vagina, and eventually out of the female. The newborn, which is called an infant in humans, should typically begin respiration on its own shortly after birth. Not long after, the placenta is passed as well.
The placenta (pl.: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation.It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ, producing hormones that regulate both maternal and fetal ...
Humans usually produce a single offspring at a time. The mother's body is prepared for birth by hormones produced by the pituitary gland, the ovary and the placenta. [2] The total gestation period from fertilization to birth is normally about 38 weeks (birth usually occurring 40 weeks after the last menstrual period). The normal process of ...
The presence of hCG in a woman's body indicates that a fertilized egg has implanted in the uterus and the placenta has started to form. 10 days after fertilization, significant hCG can be detected from woman's blood sample. [6] The levels of hCG in the body increase rapidly in the first few weeks of pregnancy, doubling every 48–72 hours. [7]
a chorioallantoic placenta that provides nutrients and oxygen to the developing embryo via an umbilical cord accompanied by a prolonged gestation period compared to marsupials. [ 2 ] a sufficiently wide opening at the bottom of the pelvis to allow the birth of a large baby relative to the size of the mother.