History of Amazon Reveals Original Name and Jeff Bezos' Temper. A number of little-known facts surrounding Amazon's rise as an ecommerce powerhouse are explored in a new book called The Everything Store: Jeff Bezos and the Age of Amazon by Businessweek senior writer Brad Stone, released on Tuesday.
There are four basic types of screening tests for Down syndrome. Some of these tests need to be done early in the pregnancy, while one is not done until 15 to 18 weeks of pregnancy (at around 4 months). âFirst-trimester screening is typically done at 11 to 13 weeks of pregnancy.
Chorionic villus sampling (CVS). In CVS, cells are taken from the placenta and used to analyze the fetal chromosomes. Typically performed in the first trimester, after 10 weeks of pregnancy, this test appears to carry a somewhat higher risk of miscarriage than second trimester amniocentesis.