Development of the placenta-labor and delivery - birth-embryology-placental maternal side formation

After the fertilized egg travels down the fallopian tube to the uterus, around 6-12 days after fertilization, it undergoes a process called implantation. The embryo's attachment to the uterine lining is known as the endometrium. Once the blastocyst contacts the endometrium, some of its outer layer cells, known as the trophoblast cells, proliferate. Then they lose their cell membranes, merge, and act as a single structure called syncytiotrophoblast. This multi-nucleate cytoplasmic mass aggressively burrows and digs its way into the endometrium and invades the uterine wall. It also starts to secrete a hormone called HCG. Hcg is a pregnancy hormone that is crucial in maintaining the corpus luteum. The corpus luteum produces progesterone and stops the menstrual cycle. hCG helps sustain the corpus luteum until the placenta takes over hormone production. hCG is often used as a marker for pregnancy detection. Pregnancy tests detect the presence of hCG in urine or blood to confirm pregnancy. hCG ALSO helps establish immune tolerance in the mother's body and modulates the immune response to protect the fetus from being recognized as foreign tissue. Elevated levels of hCG during early pregnancy are associated with morning sickness, which includes symptoms such as nausea and vomiting.