An amniocentesis is done by inserting a thin, hollow needle into the abdomen and uterus, using an ultrasound to guide the process. In mid-second trimester amnios, about 2 tablespoons of amniotic fluid are removed through the needle. The most common reason for doing an amniocentesis is to check for birth defects. It can also be used to check fetal lung maturity near term and occasionally in late pregnancy to assess anemia in babies with Rh disease. During a normal pregnancy it is often only used to check for birth defects.
This is where I have a problem with it. I see no point in getting an amniocentesis to find out if my child will have a birth defect or not, because the result of the test will have no bearing on whether I carry that baby to term or not. The typical birth defect that they search for is Down syndrome (and many abortions are then preformed based on the result). You can also search for trisomy 13, 18, etc., plus Turner and Cri du Chat syndromes. There is also cystic fibrosis and other defects. But I choose to forgo all testing because even a positive result of a defect would not have changed my mind in carrying on my pregnancy. There are many false positives reported with an amniocentesis and that would involve further testing and needless worrying.
Even some couples who know that they would never abort but would like to know if there is an issue that they can prepare for before hand do decide to get an amniocentesis. I can see the reasoning in this...if you know before birth that your child will have Down syndrome or be be born with cystic fibrosis you can research it and know what you will need to know to be prepared. But again, the tests are not 100% accurate. And the tests are also not 100% safe. One must decide for themselves whether knowing something before birth is worth the risk of a test.
Bleeding and cramping, miscarriage, amniotic fluid leakage, fetal respiratory problems, increased admissions to the Neonatal Intensive Care Unit, uterine infection, clubfoot, etc. are all listed in various resources as potential risks of amniocentesis.
Bleeding occurs 2-3% of the time and is usually resolves without problems, but is associated with a somewhat higher rate of fetal loss. The risk for miscarriage increases after an amniocentesis, it is generally thought to increase between 0.5% and 1.0%.
These are real concerns that I decided are not worth it for my pregnancy and baby. If I had serious complications in pregnancy or a possible serious problem with the baby that showed up on ultra-sound that may be easier helped if we knew what we were dealing with, I may feel the risks were worth it to see what was going on. But in my healthy pregnancies I saw no reason to get an amniocentesis.
I did have to sign a waver to opt out of these tests. The thing that gets me is that the tests are touted as normal and routine and the risks are often in small print on a pamphlet that mothers often don't read, instead taking the advice of the doctor and going through just "another routine test". I don't think that there is anything routine about an amniocentesis and I hope that more mothers will realize that there is a risk, and then decide whether it is right for them and their baby, instead of just going along with it.