Friday, July 11, 2008

Pregnancy

So after going through fertilisation, let us look more in depth into pregnancy (also known as gestation). Well, Pregnancy is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of a female. Childbirth usually occurs about 38 weeks from fertilization. Pregnancy is typically broken into three periods, or trimesters, each of about three months. While there are no hard and fast rules, these distinctions are useful in describing the changes that take place over time.
The beginning of pregnancy may be detected in a number of ways, including various pregnancy tests which detect hormones generated by the newly-formed placenta. The tests are known as Human Chorionic Gonadotrophin (HCG). Clinical blood and urine tests can detect pregnancy soon after implantation, which is as early as 6-8 days after fertilization. The tests are usually carried out on the day where a woman's monthly menstruation period is due.
After fertilisation and during the first trimester, the developing embryo becomes implanted into the endometrial lining of a woman's uterus. The embryo is a blastocyst which secretes a hormone named human chorionic gonadotropin which in turn, stimulates the corpus luteum in the woman's ovary to continue producing progesterone. This acts to maintain the lining of the uterus so that the embryo will continue to be nourished. The glands in the lining of the uterus will swell in response to the blastocyst, and capillaries will be stimulated to grow in that region. This allows the blastocyst to receive vital nutrients from the woman. During this time, the fetus is still developing by division via mitosis in the female
Months 4 through 6 of the pregnancy are called the second trimester. Most women feel more energized in this period. Although the fetus begins moving and takes a recognizable human shape during the first trimester, it is not until the second trimester that movement of the fetus, can be felt. The placenta is now fully functioning and the fetus is making insulin and urinating. The teeth are now formed inside the fetus's gums and the reproductive organs can be recognized, and can distinguish the fetus as male or female.
In the third trimester, movement of the fetus becomes stronger and more frequent and via improved brain, eye, and muscle function the fetus is prepared for ex utero viability. The woman can feel the fetus "rolling" and it may cause pain or discomfort when it is near the woman's ribs and spine. This period of her pregnancy can be uncomfortable, causing symptoms like weak bladder control and back-ache. It is also during this time that a baby born prematurely may survive.
I thank wikipedia again for the information.

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