Individual differences | Methods | Statistics | Clinical |
Educational | Industrial | Professional items | World psychology
| Prenatal testing is testing for diseases or conditions in a
fetus or embryo before it is born. The aim is to detect birth
defects such as neural tube defects, Down syndrome, chromosome
abnormalities, genetic diseases and other conditions. It can
also be used to determine its sex. Diagnostic prenatal testing
can be by invasive or non-invasive methods. An invasive method
involves probes or needles being inserted into the placenta,
e.g. amniocentesis, which can be done from about 14 weeks
gestation, and usually up to about 20 weeks, and chorionic
villus sampling, which can be done earlier (between 9.5 and 12.5
weeks gestation) but which is slightly more risky to the fetus.
Non-invasive methods, called "screens", can only evaluate risk
of a condition and cannot determine 100% if the fetus has a
condition. Non-invasive techniques include examinations of the
woman's womb through ultrasonogra