Pregnancy Childbirth 08

I did erase all the copied part that had absolutely no sense here. I want you to follow the rules... Okay?--Pierre.brawand 24 janvier 2009 à 14:24 (MET)

What is pregnancy?

For human beings, pregnancy occurs amongst the female, taking place precisely in the uterus. It is the state of carrying one or more embryos that will eventually develop into a foetus, during a period of nine months. This period starts at conception and ends at the point of delivery.

There is not a HUMAN RACE. You should use either "For humans", or "For human beings", ok?--Pierre.brawand 24 janvier 2009 à 14:24 (MET)

How does pregnancy occur?

Pregnancy takes place after fertilization, which usually occurs in the the fallopian tube, near the uterus. The sperm cells travel up the cervix and into the uterus in search of the egg. Once in the uterus, the uterus contracts and helps the sperm enter into the fallopian tubes, which are situated above. Conception takes place when the egg and a sperm cell come into contact and then forming a zygot. Pregnancy occurs by the implantation of the embryo (which is at this stage a ball of rapidly multiplying cells called the blastocyst) into the uterus about three or four days after fertilization.The embryo attaches itself to the uterine wall ( which is also called the uterine lining) and will then develop and grow inside the uterus for a period of nine months (about 266 days) and during this time, various changes occur in the mother's body in order to accomodate the growing foetus.

you could briefly mention how the embryo is generated: fertilization of two gametes to create a zygote, and then the cleavage state that generates the embryo.--Pierre.brawand 24 janvier 2009 à 14:24 (MET) Pregnancy is divided into three trimesters, each of which lasting about three months each. These trimesters help us to monitor not only the growth of the baby and the mother but also the changes occuring inside the mother's body. Although complications such as miscarriages can occur, the foetus usually grows healthily during pregnancy, recieving its nutrients from it's mother and growing in a safe and comfortable environnement which is the uterus.

the monitoring is performed not only on the embryo/fetus, but also on the mother...--Pierre.brawand 24 janvier 2009 à 14:24 (MET)

What are the different stages of pregnancy?

First trimester

The first trimester includes fertilization and implantation. During this period, the most important changes concerning both the f etus and the mother occur. The mother may experience things such as excessive vomiting, weight gain, heartburn, dizziness and tiredness due to these changes. Nausea and vomitting are usually very common and are probably the first symptoms of pregnancy the mother will experience. These changes experienced by the mother is due to the growth of the embryo, which by about the eighth week of pregnancy, would have a developping brain, tiny arms and legs and even a heartbeat. This means that from the eighth week, an altrasound of the embryo can be taken. By week twelve, almost all the fetus' limbs are developed. It is possible to find out at this stage if the fetus will be a boy or a girl because it's sexual organs would have started developing. At the end of the trimester, which usually lasts for about thirteen weeks, the mother will stop experiencing vomitting and nausea and her energy levels will go back to normal but she will start experiencing headachs due to the greater pumping of blood by her enlarged heart.

The first trimester of pregnancy lasts for about 14 weeks. At the beggining, it's an embryo 'till about 5 weeks of life and it looks like any other vertebrate embryo. (see annexe 1)

After 9 weeks de organs begin to devellop and the embryo has now a human form and is called a fetus. The fetus measures about 5.5 cm long. At the end of the trimester it looks like a mini human and we can now know it's sex by doing an ultrasound exam ( see annexe 2 & 3)

What is childbirth?

Childbirth is the step that follows the period of nine months or 42 weeks of pregnency, when the developed feotus or baby is pushed out the uterus of the mother to the outside world, along the birth canal. It happens normally spontaneously after the period of gestation, otherwise if pregnancy goes past 42 weeks, then it could be stimulated artificially. Childbirth is actually a whole process that includes two main phases: labor and delivery. The latter are themselves divided into different stages.

How does childbirth occur?

To answer this question, the main phases labor and delivery are to be developed:

Labor is the whole process of birth occuring before the birth itself, which is called the delivery.

Labor usually begins after the breaking of the bag of waters: it breaks under the pressure of the baby going towards the cervix, and lets the amniotic fluid flows away the uterus (see the section "What are the functions of the bag of waters?"). Labor can last from few hours to 24 hours, and even more; it is in this phase that the mother feels intense pain because she is undergoing contractions. These are due to the periodic tightening and relaxing of the uterus, because it is getting ready to deliver the baby. As the delivery time approaches, the contractions intensify. Eventually the baby is expelled followed by the delivery of the placenta. To describe these phenomenons occuring during labor more in detail, it is necessary to mention that labor phase is in fact divided itself into three stages:

First stage of labor

Dilation of the cervix (neck of the uterus that ends in the vagina) is the main part of this stage and the longest one, which is accompanied of contractions, and which lasts for about 14 hours during a first pregnancy, and for about eight hours during subsequent ones. This stage is parted into two phases, one is the latent (or early) labor, and the other one the active labor.

During the latent labor, that occurs first, the cervix opens or dilates to a width of about 4 centimeters, whereas at the end of the first stage it will open until 10 centimeters. While the cervix dilates progressively and slowly, the smouth muscles in the wall of the upper part of the uterus contract and thicken in order to expell the baby, causing periodic contractions, approximatively 30 seconds each at the beginning, and every ten minutes; the tightening of the muscles are stimulated by a hormone called oxytocin that the petuitary gland of the mother secrets increasingly in late pregnancy.

The pain the mother feels at these moments are tend to be mild, sometimes painless, but sometimes very painful too and the cervix may take a lot of time to dilate. Latent labor lasts from 6 to 12 hours, which is longer than the active labor because the process is slower. The mother is then encouraged to walk around, since it naturally stimulates the process, and she generally feels comfortable at this step.

Gradually the contractions become stronger, longer (40 to 60 seconds)and closer, i.e. the pauses between the periods of pain are shorter, then the cervix accelerates to dilate when its width reaches approximatively 4 centimeters: it is the beginning of the active labor, and indeed things go much faster in this phase. Whithin about 8 hours the cervix opens from 4 to 10 centimeters, and as it has been said, the contractions appear more frequently with considerable pain. The cause is that the upper muscles really start to push down the baby by contracting firmly.

At this stage, the mother is advised to relax and to use some breathing exercises to bear the pain; alternatively, if asked, the doctor can give her medication or anesthetics.

When the cervix reaches an opening width of 8 centimeters and is on the way to 10 centimeters, a phase called transition takes place, relating the first to the second stage of labor. The head of the baby starts already to descend along the cervix, thus the mother feels an urge to push it with her abdominal muscles.

Second stage of labor

References

still a lot a work to be done...--Pierre.brawand 24 janvier 2009 à 14:24 (MET)

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