Over the last decade, amniocentesis has proved a valuable tool for monitoring the progress of women whose pregnancies involve a high degree of risk to their babies. In addition, it is used to detect inherited defects in babies ahead of time, thus giving women the opportunity to abort these fetuses if desired. Thus amniocentesis has ushered in a whole new era of reproductive choice, and brought with it many unanswered questions about the ethics of that choice.
Amniocentesis is a procedure which removes about four teaspoons of fluid ("amniotic fluid") from the bag of waters ("amniotic sac") surrounding the baby. This fluid is removed through a needle placed in the mother's abdomen, and then into the uterus and bag of waters, after the mother's abdomen has been frozen with a local anesthetic. Prior to amniocentesis, an ultrasonic picture of the baby and its bag of waters will determine the best place for the needle to enter. Cells from the amniotic fluid are then grown for chromosomal studies and various chemical tests are performed as well. The results take three to four weeks to complete. The chromosomal studies will also tell you the sex of the baby.
Since amniocentesis is usually performed at 16 weeks of pregnancy, to ensure that there is an adequate amount of fluid formed, the baby is already 20 weeks old by the time its parents must decide its future.
Who Should Consider Amniocentesis ?
These include a group of structural defects resulting from incomplete formation of the spinal chord, or its bony covering, that range from mild to life-threatening. This group of defects includes missing brain, and exposed spinal column, and cause half of all still births. Children who survive with serious cases of exposed spinal chord are usually paralysed, and have severe medical problems. Children with mild defects of the spinal chord that are covered with skin, can lead rich full lives.
Other inherited problems include a range of genetic or chromosomal abnormalities. The most common of these is Down's Syndrome or Mongolism, in which there are usually three instead of two number 21 chromosomes. Down's Syndrome is a major cause of mental retardation worldwide, and people with Down's syndrome are likely to have weak cardiovascular systems, respiratory problems and run a greater risk of childhood leukemia.
Afro-American women, Mediterranean women, or Jewish women who have lived in Eastern Europe, may have a family history of diseases such as Tay Sachs disease, sickle cell anemia, and thalassemia.
However, 95 percent of cases of Down's Syndrome are age-related. At age 30, the incidence of Down's syndrome is one in 885 births; at age 35, it is one in 365 births; and at age 40 the chance of having a Down's child is about one in 109.
In the past, amniocentesis used to be reserved for women 38 or over. With increased demand, its use has been extended to the group between 35 and 38, and even to women younger than 35.
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