Pregnancy screening assesses details about mother or fetus to evaluate health of mother and fetus. This can be further explained by saying that screening either tests some aspect of maternal or fetal health or rules out any factors that pose a risk. Not all women undergo all screenings, especially some of the more invasive testing that may have some risk to a fetus, but certain types of tests, like those assessing maternal health are extremely important because they can identify problems early.
Early pregnancy screening of the fetus includes non-invasive testing like using a Doppler to listen for heartbeat sounds. Such testing normally begins during the end of the second month of pregnancy. Failure to hear a heartbeat could suggest requiring more extensive tests like ultrasound.
A more invasive test during the first trimester that can evaluate fetal health is chorionic villus sampling, which is usually performed after the tenth week. This sampling of the placental tissue is used to look for presence of chromosomal abnormalities or some genetic conditions for which the parents might be carriers. Such a screening is optional, since it runs a small but perceptible risk to the fetus. Some parents readily opt for it, particularly if they have a long history of genetic conditions.
A pregnancy screening similar to chorionic villus sampling is amniocentesis, which can take place early in the second trimester. A small amount of amniotic fluid is aspirated by needle. The fluid does contain fetal cells and these can be evaluated for certain diseases like Down syndrome.
Other forms of pregnancy screening on the fetus include continuing to listen for normal heart sounds and perhaps performing one or more ultrasounds midway through the pregnancy to evaluate fetal size, amniotic fluid volume, and to look for any structural irregularities, such as heart defects. Should heart defects be suspected, fetal echocardiograms can often confirm their presence, but these are far from routine.
Pregnancy screening of the mother evaluates for diseases or conditions that can affect mother or child. Women who are pregnant can expect blood testing and might possibly undergo testing for sexually transmitted diseases. Women often are asked to give a urine sample at the beginning of each prenatal visit. This is tested for high glucose levels because women are at risk for developing gestational diabetes, and later blood tests may check blood sugar too. Doing a blood pressure check performs another common test. Some women can have very high blood pressure, which can develop into pre-eclampsia or eclampsia.
Screening in the mother may also evaluate things like effacement or thinning of the cervix and dilation or widening of the cervix as the pregnancy nears an end. Each doctor’s visit is also a chance to evaluate growth the fetus, mother’s weight and any health concerns. One of the reasons prenatal care is stressed is because this allows doctors to frequently check that mom and baby are doing well and to quickly treat any problems that arise.