It is possible to define the third week of pregnancy as the period when pregnancy actually begins. Because during these weeks, the egg is fertilized and becomes an embryo. Along with the developments, the first changes of pregnancy are also observed.
Yeditepe University Hospitals Gynecology and Obstetrics Department Head and IVF Specialist Prof. Dr. Erkut ATTAR explained what happens in the 3rd week of pregnancy as follows:

What Happens in the Body in the Third Week of Pregnancy?

Although it is the third week of pregnancy, the body progresses very quickly. With fertilization, the zygote, the single-celled embryo, is formed and rapid division begins. The journey of the fertilized egg to the uterus also begins. In the third week of pregnancy, the process of the embryo attaching to the uterus also begins.

During the attachment and development of the embryo to the lining of the uterus, some women may show signs. There may be brown or slightly pink spotting and mild pain in the groin. There may be a slight increase in body temperature compared to normal times.

Can a Pregnancy test be Done in the Third Week of Pregnancy?

Although it is considered the beginning of pregnancy, it is still too early for a pregnancy test. Pregnancy test results are available after the 4th week, when the embryo has completed implantation in the uterus. A blood or urine hCG hormone test will clarify the result.
In the third week of pregnancy, the first trimester, there is also a risk of miscarriage, so care must be taken.

How to Avoid Risking Pregnancy During this Period?

Since this period is the beginning of pregnancy, most women may not even realize that they are pregnant. However, since the baby continues its development even if it is still in the embryo stage, paying attention to some points is extremely important for the 9-month pregnancy adventure. For this reason, harmful habits such as alcohol and smoking should be avoided. Caffeinated drinks should also be avoided. In addition, methods should be developed to eat healthy and reduce stress.