05.02 Fetal Development

In this lesson I will explain the development of the fetus in the various stages so you will be aware of what is occurring at each phase.

There are three phases when we are talking about fetal development. The first is preembryonic and this is the first 2 weeks after fertilization. There is a free floating ball of cells making its way to the uterus for implantation. When implantation occurs we have the embryonic stage. This is week 2 to 8. The last stage is fetal. The fetal stage is 8 weeks until birth.

Let’s now break these stages down to some more detail. So first is the preembryonic stage. This is the first 2 weeks after fertilization so 0-2 weeks of life. Fertilization occurs and there is a free floating ball of cells making its way to the uterus for implantation. This stage ends with implantation.

Next is the embryonic stage. This is week 2 to week 8. Conception has occurred and a heartbeat is present The heartbeat is heard and visualized on a transvaginal ultrasound around 6 weeks All the major brain structures in place. The embryo is approximately 1.2 inches long. So it’s about the size of an olive.

Our last stage is the fetal stage which is 8 weeks to birth. The circulatory system and all organs are present. The heartbeat is able to be heard on external ultrasound at around 12 weeks. The fetus is able to hear at 18 weeks and can open and close eyes at 28 weeks. The lungs continue to develop and more alveoli form. This is completed around 35 weeks. The fetus does do some practice breaths in utero but no gas exchange occurs in the lungs it happen by way of the placenta.


Therapeutic management at this point in the pregnancy is not a lot but we need to ensure that any medications that the patient takes are safe since she is conceiving. She needs to be taking prenatal vitamins to ensure proper nutrition for proper development. Education at this point will revolve around safe medications, no alcohol, and ensuring they take prenatal vitamins.

Reproduction and human development are the concepts for this patient because fetal development starts with reproduction and then fetal development is the process of human development.
Ok so to review everything and wrap it up there are three stages in fetal development. Preembryonic is first. It starts with fertilization of the ovum. Once fertilized it becomes a zygote. Cell division occurs and now it becomes a blastocyst. Remember a blastocyst is a ball of cells. This ball of cells travels to the uterus. Next is embryonic. This begins with implantation in the uterus and now early development will occur. This stage of development is from 2 weeks to 8 weeks. The last stage is the fetal stage. This occurs at 8 weeks to delivery. This is the final stage so all organ development and growth will occur.

Make sure you check out the resources attached to this lesson and review the time frame of each stage as well as what is occuring in each stage. Now, go out and be your best selves today. And, as always, happy nursing.