The first trimester is 12 weeks from the last menstrual period (LMP) or 10 weeks from the start of the developmental stage where the egg gets fertilized by the sperm. At the moment of conception, the fertilized ovum, which is only a single cell, weights .15mg and merely .005 inches in length. There are four main events that happen during the first trimester: cleavage, implantation, placentation, and embryogenesis. Cleavage is basically known as a sequence of cell divisions that initiates directly after fertilization. The zygote is the first step in the developing process. It is made up of the DNA from the two parents and it is formed once the sperm fertilizes an egg cell. The zygote becomes a pre-embryo which then turns into a blastocyst, which is a multicellular complex. A blastocyst is basically a hollow structure that houses thousands of cells and will later turn into the skin of the fetus. The cleavage process ends when the blastocyst connects with the uterine wall. Next is implantation, this process begins when the blastocyst connects to the endometrium layer of the uterus. This step is mainly being used for the …show more content…
All the organ systems become fully functional and the baby could survive at any point during the 3rd trimester will proper medical attention. This trimester starts at 28 weeks where the eyelashes are formed and the eyes are partially open. The baby has a 90% survival rate at this point. Following that the baby’s bone are fully developed and the red blood cells form in the bone marrow. At 31 weeks the central nervous system is fully functional and the lanugo that once covered the baby’s body starts to fall off. The body is able to absorb essential vitamins and minerals from the intestinal tract and the baby is able to practice breathing. After that at 33 weeks the eyes start to dilate, constrict, and detect light along with the baby gaining weight rapidly, at a pace of about ½ pound a week until birth. The organs are 100 percent functional by 37 weeks and at this time the fetal position shifts resulting in the head in a downward position for birth. The 3rd and final trimester ends at 40 weeks which is also known as the due date. It is common for the baby to exceed the due date by a couple of weeks and it should not be a big concern. When the baby is ready to come out the mother will start to dilate and contract and should be brought to the hospital or birthing center immediately. This trimester is filled with mainly the baby just growing and maturing in size and