Six to 10 days after fertilization, the embryo attaches, or implants, itself into the lining of the uterus. During the next week or so, the embryo receives its nourishment and oxygen from the cells that make up the lining of the uterus. The two layers of cells become more pronounced.

blastocyst

First, the zygote becomes a solid ball of cells. Then it becomes a hollow ball of cells called a blastocyst. Inside the uterus, the blastocyst implants in the wall of the uterus, where it develops into an embryo attached to a placenta and surrounded by fluid-filled membranes.

Once the egg travels down the fallopian tubes and becomes a blastocyst, it begins the process of implantation in the uterus. Implanting gives the blastocyst a blood supply so that it can start growing into a fetus. Along with cramping, you may experience what is called implantation bleeding or spotting.

Endometrial Problems. The lining of the uterus is receptive to the embryo for only a brief time, called the Window of Implantation. It is possible that a perfectly normal embryo might not implant because the lining was not ready for it.

Summary: Nearly as many women who received only one embryo at a time gave birth as women who received two embryos. At the same time the risk of giving birth to twins is minimized.

In general, an average of 8 to 14 eggs are typically retrieved from a woman’s ovaries with IVF; however, its ultimately not the number of eggs that matter but the quality. 1 high quality egg is better than 20 poor quality eggs when it comes to success rates.

The “Trigger Shot” is the final injection before retrieval. So out of these 12 retrieved eggs, taken at the peak of average growth without ovulating, we expect that an average of approximately 80% will be mature.

Risks from the egg retrieval include pain, infection in the pelvis and ovaries, injury to the bowel, bladder, uterus, ovaries or major blood vessels. Since the procedure is done under ultrasound guidance and the needle can be seen on the ultrasound, the chance of serious problems is extremely small.

For Successful In Vitro Fertilization, Women Should Harvest 15 Eggs. A dozen eggs might be just the right amount to buy at the grocery store, but when harvesting human eggs for in vitro fertilization (IVF), 15 is the magic number, resulting in the greatest chances of a live birth, according to a new study.