A fertilized female human egg typically attaches to the lining of a woman's uterus within ten to 14 days of conception.
More Info: There is often what's called "implantation bleeding" as a sign of this earliest phase of pregnancy. The bleeding is light and does not last long, usually one to two days. It also does not affect all women, and is commonly mistaken by first-time mothers-to-be as early menstrual period bleeding. Only a very few women experience implantation bleeding that is heavier than a normal period.
A critical element for human eggs are so-called granulosa cells, or handmaidens. They envelop a woman's eggs and feed them with hormones and nutrients, so that they can develop properly and become optimized for the conception and implantation stages. Researchers recently found that two proteins, c-Jun and TAF4b, are critical to the proper development of these handmaiden layers. The two substances combine to provide the genetic code underpinning for healthy granulosa cells.
A full understanding of the functioning of healthy granulosa layers is expected to positively impact both the fields of in-vitro fertilization and ovarian cancer treatment. Without the TAF4b protein for example, laboratory mice became infertile. But the big surprise for researchers was the second c-Jun protein. Until recently, scientists had not realized that his protein, also found in certain cancers, was also present at the most fundamental of female life-giving stages.
How Is Pregnancy Defined?
What's amazing about the idea of conception and implantation is that in the United States, the official definition of pregnancy varies widely. Some states define pregnancy beginning at fertilization, while others pinpoint the start at conception. In 1998, the U.S. Congress narrowly rebuffed a law that would have federally mandated the definition that pregnancy begins at that earlier conception stage. It is a battle the pro-life activists are not ready to soon give up, and recently, with the development of more sophisticated contraceptives, it is expected to be lobbied for as a law once more.