During pregnancy, the unborn child goes through several stages of development. The baby begins as nothing more than a single-cell organism, and with each stage, he progresses until he becomes a human being who is completely developed and able to survive outside of the womb. Every stage of development is critical to the overall process of the birthing experience. These progressions, especially those that occur during the early stages of the pregnancy, can rarely be duplicated outside of the mother’s womb.
Fertilization
Every month, a woman experiences her menstrual cycle. During this cycle, the process called ovulation occurs. This process consists of one of the ovaries releasing an egg. According to The Merck Manuals Online Medical Library, the egg travels from the ovary to the end of the fallopian tube where it waits to be fertilized. While the egg is waiting, sexual intercourse allows for sperm to penetrate the egg after traveling into the uterus from the vagina and cervix. When the sperm fertilizes the egg, a zygote is created.
Blastocyst
A few days after the zygote has been created, it will enter the uterus and start to go through the cellular division process. According to the website Pregnancy Period, during this process, the placenta is created and attaches itself to the wall of the uterus. Once the placenta is attached, the zygote becomes known as the blastocyst, and it starts to form the amniotic sac and develop membranes in approximately 10 days.
Embryo
The blastocyst will become an embryo, and the organs will start to develop at around the three-week mark of the pregnancy. During the embryo stage, the basic shape of the baby will start to develop. Around the 20th day of the pregnancy, the baby will start to develop her heart and blood vessels.
Fetus
Approximately 12 weeks into the pregnancy, the embryo becomes a fetus. The Merck Manuals Online Medical Library states that once this occurs, the fetus is large enough to fill up the entire uterus. Shortly after becoming a fetus, doctors can start to identify the sex of the baby. About eight weeks after the embryo becomes a fetus, the baby will begin to move around in a way that you will be able to feel from within.
Final Stages
Starting at around week 24, a fetus may be capable of surviving outside of the uterus, although full gestation is certainly preferable, notes The Merck Manuals Online Medical Library. The brain and lung function are also developing around this time. Once the baby is born, his brain will continue developing well into his first year of life.
