As we learn more about how reproduction works at the cellular level, we can have more control over the earliest stages of a baby's development. With the mapping of the human genome in 2000, our understanding of how DNA affects human development is only just beginning. Two Key Things to Remember Human reproduction is a tricky business. When you also consider the enormous complexity of the human genome, with its billions of DNA pairs, it becomes clear that reproduction will always have an element of unpredictability. To a certain extent, we have always hoped to control our children's characteristics through our selection of mates.
Some parents have a high likelihood of passing on the genes for a disease.
This procedure, first used in 1990, helps doctors detect severe genetic disorders very early in a pregnancy. If it is used to screen test tube babies, an embryo with an inherited condition need never be implanted in the womb. The PDG technique could also be used to screen embryos even when there is no known risk of inheriting diseases. Also, doctors could screen for unpredictable disorders in the chromosomes - disorders which could result in miscarriage, birth defects, or diseases like Down's syndrome. It can also be determined several weeks into pregnancy - at which point an abortion is required if the baby is not of the desired sex.