As a baby is formed inside the mother’s womb, it goes through a number of stages right from the day of conception to the day of birth. Soon after the egg is fertilized by a male sperm during conception, the fertilized egg becomes a zygote. The newly fertilized zygote then travels down the fallopian tubes towards the uterus where it attaches itself on the wall of the uterus so as to begin the process of blastocyst development. Generally, the whole process of the zygote traveling to attach itself on the uterus takes 5-8 days after fertilization. The blastocyst development becomes complete 10-12 days after the fertilization of the egg and it is at this stage that the zygote becomes an embryo. It is only after the 8th week of pregnancy that the embryo becomes a fetus and it remains a fetus until birth.
When the pregnancy is at the embryonic stage, various significant stages of development will occur. These development stages include the growth of the placenta, the beginning of the development of the internal organs and the external features. It is also at this stage that neural development commences. At the end of this embryonic stage, the embryo will be in a position to make minimal movements, the heartbeat will appear and the formation of facial features will be in progress.
To make it clearer, 2-3 weeks after fertilization of the female egg, this fertilized egg will have already attached itself on the wall of the uterus and the umbilical cord will have started developing. During this period of time, the development of the embryo will be focused on the spine and the spinal cord. Soon after, it becomes more drawn out and begins to look more human as the heart and gastrointestinal tracts begin to develop too.
At 4-5 weeks, the body will produce hormones that will end the menstrual cycle of a pregnant woman. The development of the embryo proceeds with the heart starting to beat and to pump blood. Some tissue will grow into the spine alongside other bones and where arms and legs will later form, limb buds will appear.
By the 6th-8th, the embryo should be about half an inch in length and should have eyes and tiny openings where the mouth and nose will eventually form. Hands with visible fingerprints will also be present at this stage of time and the development of most organs will have been complete with the only exception being the brain and the spinal cord. The embryo will be in a position to make slight movements since neural development will have advanced far enough to allow this. It is also at this point of time that hair begins to form along with some facial features. Soon after, the tail disappears and the embryo begins to look more human. It is after the 12th week of pregnancy during which the embryo will have become a fetus that the baby’s sex can be determined.
According to experts, it is at the embryonic stage that birth defects will develop since it is at this stage that organs are formed. Most miscarriages have also been known to occur at this stage of pregnancy.