Gastrulation is a key process in embryonic development occurs in the fourth week of pregnancy and from here the embryo will have three layers of tissue from which all organs and tissues are formed.
At this stage, the woman may experience the impact of hormonal changes, something that may alter her emotions. However, physical body changes aren’t noticeable at a glance yet.
It corresponds to the first week of the second month of pregnancy. The head now is more rounded and the internal organs begin to be formed, given that gastrulation took place a week ago.
That week marks the finish of the first month, there are no important physical nor emotional changes. If they are not tested, they don’t even realise they are pregnant.