How long after conception does the fertilized egg implant?
The fertilized conceptus enters the uterus as a 2- to 8-cell embryo and freely floats in the endometrial cavity about 90-150 hours, roughly 4-7 days after conception. Most embryos implant by the blastocyst stage, when the embryo consists of many cells. This happens, on average, 6 days after conception. The blastocyst itself then induces the lining changes of the endometrium, which is called decidualization. It then rapidly begins to develop the physiologic changes that establish maternal-placental exchange. Prior to this time, medications ingested by the mother typically do not affect a pregnancy. What is the most accurate pregnancy test to use? Serum beta?human chorionic gonadotropin (HCG) is the hormone produced by the syncytiotrophoblast beginning on the day of implantation, and it rises in both the maternal blood stream and the maternal urine fairly quickly. The serum HCG test is the most sensitive and specific, and the hormone can be detected in both blood and urine by about 8-9 d
