Pregnancy Week 4
Once this now ball of cells, called a blastocyst reaches your uterus, it will implant itself into the endometrium, the uterine lining.
The placenta that will protect and nourish your baby throughout your pregnancy, will begin to form from this implantation site and the beginnings of the umbilical cord appear.
The three layers of the blastocyst; the ectoderm, endoderm, and mesoderm will eventually develop into your baby's skin and nervous system, digestive and respiratory systems and muscle and skeletal systems, respectively.
The fourth week of your menstrual cycle is actually considered the fourth week of your pregnancy.
If the egg was fertilized, implantation should occur by the end of this week.
You may experience very light staining or spotting at the time of implantation. A Home Pregnancy Test (HPT) may already reveal a positive.
Once the egg implants itself into the uterus, you are considered pregnant. Congratulations!