Just like how modern science explains this pregnancy in three trimesters. Likewise, Ayurveda also explains the development of the fetus. Just we correlate then the physical structure development of the first trimester is correlating with the ultrasound features. The second trimester in Ayurveda is more explaining towards the mind and personality development and it’s a connection with the mother inside the womb.
And the last trimester is towards, the nourishment of that fetus and easy evacuation of the fetus into this world. So the entire three trimesters explained in Ayurveda as a month-wise development of the fetus and this fetus development depends upon the quality of the shukra and shoumita and the Atma, which is willing to enter into this womb.
So the father’s shukrdhatu or the quality of the sperm and quality of the air decides the physical structure of the fetus, as well as the mind development and personality characteristics. And I hope in the future a lot of cities will come to prove these Ayurvedic theories, how this bunch of habutas, tribhushas and the dhatus and the ojas and how the vayu paves the way for the normal delivery of the child.