Fetal Development Week By Week – Week 4

Your fetus is about the size of an apple seed at this time.  You may begin to have signs that you are pregnant at this time, as by the end of week 4 you will have missed your period.  Other signs that you are pregnant include:

-  Nausea and vomiting

-  Breast tenderness and darkening of the areolas

-  Excessive salivation

-  The need to urinate more frequently

-  Skin changes, including breakouts

-  High basal temperature, a temp over the coverline for 18 days in a row

-  Fatigue

-  A missed period

At this point your embryo has three main brain sections: the forebrain, middle brain and hindbrain.  Parts of the eye, including the pigment and optical stalk are visible.  The beginning of a mouth with tongue is distinguishable and the thyroid and lymphatic system is forming.  Lung buds are forming and the heart is quite large, with circulation well established.  The first thin layer of skin is formed and buds that will become arms and legs are becoming visible.

At this point you may take a home pregnancy test.  Be sure and read the directions carefully and contact your healthcare provider with the results.  If you haven’t already researched OB/GYNs in your area, this is the time to do this.  Prenatal care is imperative to the development of a health baby.

Related Weeks

Fetal Development – Week 3 | Fetal Development – Week 5



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