Fetal development, the several states of development that a fetus undergoes inside the womb, is an intricate and complex process. It starts when the egg and sperm cells come into contact and continue until the baby is formed. From the point of conception up until the delivery of the baby, several intricate steps have to take place.
Stages of Fetal Development
According to the Cleveland Clinic, fetal development has three main stages. These are, namely, the germinal, embryonic, and fetal stages.
Germinal Stage
According to Very Well Mind, this stage starts in the first two weeks post-conception. Among all three stages of fetal development, it is the shortest one.
The Cleveland Clinic adds that the germinal stage starts when the egg and sperm join inside the woman's fallopian tube. A zygote results from the fertilization of the egg cell. This zygote spends around a week moving down to the uterus. While doing so, the zygote divides several times and has two different structures. One structure becomes the placenta, while the other becomes the embryo.
As cell division continuously occurs, the zygote becomes a blastocyst, which reaches the uterus and implants into the lining. When this implantation succeeds, the body starts producing the necessary hormones for pregnancy. This also prevents the menstrual period from taking place.
Embryonic Stage
The embryonic stage runs from the fifth to the tenth week, as the Family Doctor explains. In this particular stage, the baby is now called an embryo.
The blastocyst starts taking on unique human features. The head, mouth, limbs, and structures like the neural tube start forming. By the sixth week, the pulse of the embryo starts getting developed. Buds that become legs and arms also start forming this week. When the eighth week ends, most of the systems and organs of the embryo will have taken shape.
For several women, this is the point where they start experiencing morning sickness.
Fetal Stage
The fetal stage starts in the ninth week of pregnancy and continues until the baby's birth. During this stage, the embryo develops into a fetus.
Very Well Mind explains that this period marks vital brain changes. The structures and systems developed in the previous stage keep developing during this stage. The neural tube turns into the spinal cord and brain, while neurons also continue forming. After these neurons form, they start migrating to their designated regions. Neural connections, or synapses, also start developing in this stage.
Reflexes also start emerging. The fetus starts making reflexes using the legs and arms.
In the third gestational month, sexual organs start getting differentiated. By the end of this month, all body parts will have formed. By this time, the fetus should weigh around three ounces.
The third month's end also marks the end of the first trimester. In the second trimester, the fetus' heartbeat strengthens while other systems develop even more. The fetus grows roughly six times larger, while its brain and central nervous system are more responsive.
During the seventh month up until the fetus' birth, the fetus grows, becomes heavier, and prepares for life beyond the womb. The lungs start contracting and expanding to prepare the fetus for breathing.
The Cleveland Clinic adds that the risk of miscarriage drops after the first 12 weeks or by the end of the first trimester. Most people also start feeling relief from morning sickness.
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