At the beginning of the third week of pregnancy there is ovulation and fertilization. The woman has not missed her period so she will not know that she is pregnant.
On the first day, at 16-20h post-fertilization, the zygote appears. On day two, the embryo has four cells, day three eight and day fourteen, at this moment it is called a morula. The fifth day follows the increase in cells and is called a blastocyst.
On the sixth-seventh day the embryo reaches the uterus and begins its adhesion to the endometrium, implantation. Normally the woman during this week does not have any symptoms.
Read the full article on: 3 weeks pregnant – the start of the development of the embryo ( 34).
Jon Ander Agirregoikoa
Graduated in medicine from the Pays Basque University, with a specialization in obstetrics and gynaecology. He has several years of experience in the field of assisted human reproduction and is co-director and co-founder of the ART clinics. He also combines his medical activity with teaching at the Pays Basque University.